Category Archives: Grand teint

Persicaria tinctoria

Three strains of Japanese Indigo tested and observations on indigo extraction

An article by Ashley Walker
© copyright 2017

This year I had planned to carry out a tightly controlled experiment to look for variation in the amount of indigo produced by three fairly distinct strains of Japanese indigo. However due to a prolonged and still undiagnosed illness, my plans were thwarted and the experiment did not work out quite as I had hoped. However, on 12th and 13th October 2017, with help from Brian Bond another keen plant dyer, I did manage to complete a test of the three plants although the results are not directly comparable due to different planting times and maturity of each variety.

The strains

Broad or Rounded leaf indigo

Persicaria tinctoria

Round or wide leaved Indigo. Directly sown bed

Grown from seed originally from the USA (from fellow natural dyer Pallas Hubler in Washington State on the west coast) who sent a few seeds over to Brian in 2013. We have been growing and saving seed from this strain ever since so it is possible that it has become adapted to growing in our soil.

  • Late flowering (October into November)
  • Pink Flowers
  • Compact short flower stems
  • Wide short or rounded leaves
  • Foliage pale to mid green
  • Easily damaged by high nitrogen levels in the soil. Grows poorly in cool overcast weather.

Long leaf indigo

Persicaria tinctoria

Long leafed Japanese Indigo in full flower.

Seed for this was obtained from the German supplier Rühlemann’s. Unfortunately this was in full flower by the time I was able to harvest it for the test and from previous experiments I know that once indigo has committed itself to flower production the amount of indigo in the leaf falls dramatically.

  • Large long pointed leaves
  • Pink flowers
  • Long delicate flower stalks
  • Early flower (September-October)
  • Dark green leaves
  • Very tolerant of high nitrogen in the soil and generally more robust.

An in-between white flowered strain

Persicaria tinctoria

Intermediate white flowered Japanese Indigo

Persicaria tinctoria

Intermediate strain of Japanese Indigo with white flower.

The seed was obtained from Lisa George Fukuda a fellow plant dyer in Guernsey who had it originally from Teresinha Roberts at Wild Colours

Unfortunately this was planted out late in the year (August) so as yet I know little about its habit as there has not been enough time for it to grow to full maturity.

  • Longish leaves
  • White flower
  • Easily damaged by high nitrogen fertilizer.
  • Mid green leaves
  • Quickly bushes out, highly branching.

All three strains were grown on the Natures Rainbow allotment in Hitchin in a chalk soil with a strong application of Fish, Blood and Bone plus some chicken manure pellets.

Persicaria tinctoria

Leaves from all three strains.

Persecaria tinctoria

Rounded leaf Japanese Indigo growing with the Long Leaf strain in the greenhouse. Here they look like two completely different species.

The experiment

After stripping the leaves from the freshly cut indigo stalks, 220g of leaves from each strain were slowly heated from room temperature to 80°C in stainless steel pans with 4 litres of tap water. The pans were stirred at short intervals throughout. Note: the weight of leaves was determined by the amount of the long leaved strain that I could harvest from shoots that had not yet come into full flower as I wished to minimise the effect of flowering on indigo production. The amount of water in the pans was deliberately large as I wished the final colour to be on the pale side as variations in pale colours are easier to distinguish. More water also means the pot is easier to stir before the leaves are cooked.

Heating to 80°C took about 35 minutes. The pans were then taken off the heat and allowed to cool, free standing in the air for 1 hour. (The air temperature was appoximately 20°C).

Persicaria tinctoria

Intermediate Japanese Indigo extraction bath with container of liquor to show gray colour. Photo taken just after pan was removed from the heat.

At this point no difference could be noticed between the different pans. The liquor in each pan being a pale greyish blue in each case.

After one hour the leaves were removed by straining through an old pair of tights into a large plastic bucket. Half a cup of household ammonia was then added to the liquor. Taking care not to breathe in hot fumes, this liquor was poured back and forth from bucket to pan 10 to 15 times to aerate and oxidise the indigo precursor to indigo. The colour of the liquor changed from grey to yellow green, with the round leaved plant giving the darkest colour change and the long leaved plant the least. This is a good indicator of how much indigo is present in each pan.

Once oxidised to indigo, the liquor is now in a stable form and can be left for long periods without any loss of indigo. The reduction vats (indigo dye baths) were set up the following day as follows. The pans were heated to 50°C, one level teaspoon of Spectralite (Thiourea Dioxide) was added to each pan, gently stirred in and left for 30 minutes for the indigo to reduce to its soluble form. Identical weight skeins (26g) of wool were added to the baths at 50°C and left for 20 minutes before removal and oxidation in the air. The dye baths were kept in a hay box to maintain constant temperature during the dyeing.

The results

Japanese Indigo

First results showing a surprising difference in colour obtained

The long-leaved plants (left) were disappointing only producing an ice blue colour. The white-flowered intermediate-leaved plant gave a slightly deeper shade but still pale (centre). The round-leaved plant produced a respectable light blue (right).

The poor results for the long-leaved plants was understandable because of their flowering state, however I was surprised the colour was quite so pale. The good results for the round-leaved plant was a real surprise as I had become convinced these plants would not be the best. Overall the pale colours made me worry that I had not optimized the process and I decided to repeat the experiment for the round-leaved and intermediate-leaved white-flowered plants (I had no more of the long-leaved plant so I could not replicate this one).

On the second run I made one change which was to slow the cooling of the extraction bath after reaching 80°C by placing the pans in hay boxes. For this experiment, using 4 liters of water I was aware that this small amount of liquor would cool quickly, perhaps too quickly? An experiment we conducted some years ago revealed that premature cooling of the extraction bath resulted in a dramatic loss of indigo when processing woad leaves. Two years ago we discovered that leaving the bath at a high temperature for more than one hour also results in a loss of indigo so I have become wary of putting large baths in hay boxes which are capable of maintaining a high temperature for hours.

In this second run the results from the white-flowered intermediate-leaved plant improved but the round-leaved plant still produced the better result (which itself was no better than in the first run).

Skeins of wool dyed with Japanese Indigo

Second run with intermediate white flowered indigo plant compared to rounded leaf plant.

Skeins of wool dyed with Japanese Indigo

Comparison of intermediate white flower strains. The difference between quick and slow cooling of the extraction bath.

Wool dyed with Persicaria tinctoria

No real difference between runs for the Rounded leaf strain.

Discussion

In theory all three plants should have produced broadly similar amounts of indigo. That they did not could have been due to genetic differences but as noted above all three plants were at different stages of development having been planted at different times and the round-leaved strain had possibly adapted to the local soil over the 4/5 or so years I have been growing it. The poor results from the long-leaved plant may have been entirely due to their flowering state. The intermediate-leaved white-flowered strain had only been planted out in late August and may not have had sufficient exposure to the sun to develop much indigo.

The diversity of results shows how critical it is to grow and harvest the plant at the right time. I was certainly concerned that harvesting the plants in October was a risk, as all three varieties were producing flower buds (although only the long-leaved plants were in full flower). Later I extracted a concentrated bath of indigo by making up a large pan crammed full of leaves and only enough water to barely cover the leaves when they were pressed down forcibly. The results were pleasingly strong indicating that the leaves were still fully charged with indigo.

Skein on right dyed with a strong indigo dye bath

Skein on right dyed with a strong indigo dye bath

I will certainly be making strenuous efforts to continue to save the seed from the round leaf strain whatever the reasons for the underperformance of the other two strains!

Confirmation of results

Since this post Leena Riihelä writing in her blog (see Riihivilla) has confirmed that the long or pointed leaf variety of Japanese Indigo does not produce as much indigo as the broad or rounded leaf variety. Leena who also grew three strains of Japanese indigo this year also speculates that the broad leaf (rounded) variety originated in Japan. (The long leaf variety may come from Northern Japan or China). She is also able to confirm that the long leaf variety flowers much earlier. Leena is based in Finland which has such a short growing season that the rounded leaf variety does not have time to produce seed. Leena has a wealth of experience to share about indigo and other natural dyes so please visit her blog and web site. (see below)

Thanks to:

Brian Bond
Leena Riihelä at Riihivilla
Lisa George Fukuda
Pallas Hubler

Indigo dyed wool

The range of blues obtained from the three strains of Japanese indigo.

Madder Red by Robert Chenciner

Looking into Chenciner’s Madder Red

An article by Ashley Walker
© copyright 2017

Madder Red – A history of luxury and trade (2000) by Robert Chenciner
published by Curzon Caucasus World ISBN 0 7007 1259 3

This book is devoted to all aspects of the history of madder from cultivation, through process, economics and use of dye and pigment. The author has collected together in this one reference work the result of many years research.  It is a mine of information. The book is not a light read and the first time I was able to get hold of a copy I only read the chapter on madder cultivation which I found of particular interest. Since obtaining our own copy I have discovered the book contains many additional snippets of information on cultivation and use which compliment our earlier article (see here). My interest, from the point of view of the small scale grower and crafter, covers those aspects of growing and using madder that could be employed on a domestic scale. In the remainder of this article I attempt to extract information of practical use (see comments in Red).

The Madder Plant

The book contains information collected from multiple sources from all over the world but chiefly from the Caucasus and Russia. The focus is mainly on Rubia tinctorum  but other plant sources of red dye are also noted, particularly Rubia peregrina (Wild Madder) which was used quite often when tinctorum was not available. The roots of peregrina contain purpurin and little or no alizarin. Purpurin was valued for producing superior pink and violet shades.

Plant diversity, propagation and seed fertility

In different places madder appears to be adapted to local conditions and taking seed or plant material to grow in other parts of the world often resulted in failure – though this may have been due to inexperience of the new farmers. The book also confirms my own experience that the seed of madder is difficult to germinate and can easily become infertile due to poor storage.

For the home grower this means using the seed as soon as possible (within a year of harvest).

Farmers invariably preferred to sow seeds direct but only the most experienced could do this with success. New farmers preferred to grow the seeds in nurseries and then transplant into the fields when big enough or take rooted shoots from a field being harvested. Transplanting was harder work (and so more expensive) but ensured a greater chance of success.

Crop rotation, maintenance and soil fertility

Maintenance

Six months after planting, the rows of madder plants were “earthed up” (like potatoes) to encourage the plant to put out side shoots (underground stems) and protect the plant from drought in the summer and hard frosts in the winter. This practice is also reported as improving the quality of dyestuff.

For the home grower this seems a sensible activity if you like to grow madder in rows as it would allow the roots to be more easily dug out.

The main maintenance job is reported as weeding, with the most difficult weed being couch grass. I have to agree with this as couch grass has a very similar habit to madder and also forms a mat of underground roots which are extremely difficult to untangle once they get a grip.

Crop rotation and soil fertility

Most of Chenciner’s references to soil fertility indicate that madder harvests (weight of root and quality of dyestuff) will decrease over several years if grown in the same soil continuously – even if the soil is well fertilised with manure. A figure of approximately 6 to 12 years is mentioned as the maximum length of time that madder could be grown economically in the same field. After this time the land had to be left fallow or rotated for several years (4 to 12) before any further madder crops could be grown. Typical rotational crops were rapeseed, beans, wheat, hemp, turnips, beet, potatoes and cabbage.

Several references are made to observations that madder grew best on virgin ground which is much the same as any other crop, but the failure of manure to restore fertility suggests a depletion of some micro-nutrient not present in manure. The only suggested method of restoring fertility quickly was to add “natron” and common salt. Natron is a mixture of hydrated sodium carbonate salts and other salts found in dried up lakes.

For the home grower it may be possible to substitute common washing soda for natron but I would not recommend doing so without careful experiment first to find out how much to apply. Washing soda is a powerful alkali and sprinkling it on soil could do serious damage.

Adding small quantities of sea salt (35g per m2 about twice a year) may be a better solution but be careful not to overdo it. Rock dust may also do the job.

How long to grow the plant before harvest?

Throughout its history this subject has been the source of much discussion and the author comes to two conclusions:

  1. Older roots (3 to 5 years) produce the best quality dyestuff.
  2. Economically it was best to harvest after 1 to 2 years.

As you can imagine 3+ years is a long time to wait before being paid, particularly if as an “adventurer farmer” you had to pay rent on the land/accommodation and feed a family during this time. Most successful ventures appear to have been run by established land owners who had minimal overheads and additional sources of income. Some farmers did practice a form of partial harvest where a trench was dug beside the row of madder plants. Roots found in the trench were harvested without killing the main plants which continued to grow for a further year or two.

This practice makes home growing of madder considerably less of a wait though the final harvest may be reduced.

Harvest and processing of madder root

Steaming

The first procedure after digging the roots was to steam them, a practice carried out in the field by a team of specialists. All sources are clear that this process increases the amount of dyestuff in the root and after about 4 to 5 hours the roots would turn from yellow orange to a strong red. A hole was dug in the ground and a fire lit. When the surrounding soil had become baking hot, madder roots were piled on top and then the whole heap was covered in damp cloth or similar material to keep the hot air in.

Although we have never tried this I see no reason why it would not be possible to do this at home using standard vegetable steamers. The exact method will need to be worked out by experiment.

Washing

There are very few reports of root washing in the book and when it is mentioned it is not recommended for fear of loss of dyestuff. I would guess that the growers wanted to keep even the poor quality brown dyes found in the thin skins. Any soil clinging to the roots would just add to the weight of the final product, so more profit!

Drying

In the Netherlands and Britain this was done in specially built heated drying houses as the climate here was not hot enough to dry outside. Even in the Caucasus and other hot dry areas most growers preferred to dry in the shade rather than direct sun. This slow drying is reported as another essential process to further increase the amount of dyestuff in the roots. Roots were often stored for one or more years to allow them to mature before being pounded into a fine power or “krap”. The roots had to be brittle dry before pounding otherwise the root would stick into a hard cake.

For the home grower the important features of this drying process is the temperature and the length of time. The recommended temperature was between 20°C and 30+°C so drying in an airing cupboard would probably work well with storage in a warm dry place after the roots have dried out completely.

Fermentation

Fermentation was sometimes done before pounding, sometimes afterwards and involved placing the root material into a vessel with water for a short time (a few days) during which time the sugars in the root were fermented out. Removing the sugar was important as later fermentation in the dye bath interferes with the dyeing process.

From the home dyer’s point of view this is not so important unless you make your madder dye bath a day or two before using it.

Pounding

When the madder industry was in full swing the roots were pounded in large horse-powered or water-powered mills and the resulting powder or krap was sorted into a variety of grades. The main problem besetting the root processors was separating out the “tough” outer skin which contains the brown dyes that would dull the final dyed product from the inner “parenchyma” part of the root which contained most of the dyestuff. Exactly how this was done is not explained but logically krap was probably sieved into coarse and fine fractions and the first powder produced after partial pounding would have presumably contained most of the bark.

For the craft dyer pounding is not really an option. It may be possible to grind the root in coffee bean grinders but only if you are prepared to say goodbye to the grinder. The metal blades in such grinders could be a problem if they become rusty and end up adding iron to the dyestuff which would sadden the colour. Chenciner reports that some pounding mills used wooden hammers with ends strapped in metal (possibly iron) so the danger cannot be catastrophic.

There has been some confusion amongst today’s craft dyers about exactly which part of the root contains the dyestuff. Nowhere in the book does the author note the differentiation of root into ‘true roots’ and ‘underground stems’ or rhizomes, although some of the quotes from historical documents do allude to this. The root is invariably described as having a thick tough bark but this is clearly an impression formed by looking at the dried root. The skin of fresh root is very thin and can be easily scrubbed away on an individual root but this is probably not possible on a large scale without losing a lot of the underlying dyestuff. The position of the dyestuff in the root is usually described as being just above the woody cortex, but again this is probably a description of a dried root where the soft fleshy outer material has shrunk to a thin layer of concentrated dye bearing material just covering the woody cortex.

Rubia tinctorumIn the shrinking process, the outer skin wrinkles up and appears to become quite thick.

In theory it would be possible to hand wash fresh roots then pound the roots in a strong pan until the woody cores could be removed and the remainder left to dry. This would be very labour intensive however and the inner pith from root stems (which also contains dyestuff) would remain in the removed woody material.

During a Turkey Red workshop run by Debbie Bamford (The Mulberry Dyer) at the 2013 Spinners Weavers and Dyers Guild summer school an experiment was done to try and separate the outer part of the root from the inner cortex and test the resulting material for dye strength and colour. Most of the commercially obtained dried root was actually root stem with the characteristic central dot of red pith. The outer layer of bark and inner dye-rich material was shaved off with potato peelers, down to the pale woody cortex. It was not possible to remove all the dark material. Equal weights of shavings and inner cortex were then used in identical dye baths. The shavings gave the darkest red with little if any dulling due to the presence of outer bark.
root-experiment

For the home dyer wanting the brightest reds the easiest way to remove the brown dyestuffs from the bark is to set up the dye bath using your preferred recipes and after a first heating of root pour off the liquor and replace with fresh water. (See Jenny Dean)

Refining the powdered madder root

When the Madder industry expanded in the 18th and 19th centuries it was not long before competitive manufacturers began to invent new mechanised ways of refining the krap to increase its quality. The first breakthrough using a complex chemical treatment resulted in “garancine” which was later purified even further into “flowers of madder” which was almost pure “alizarin” (the main dye chemical in madder root). These refined products enabled the dyer to dye product quickly, easily and reliably.  Krap became an inferior grade product and perhaps contributed to its entry into the dictionary as the word “crap” meaning rubbish.

For the home dyer, refined madder root products are still produced and sold as madder extracts but these are expensive and I think less exciting than growing your own or making do with chopped root or krap. Home refining is possible (see Michel Garcia) but you do need some specialist laboratory equipment.

Economics

Chenciner is particularly interested in the economics of madder growing, processing and use. As a very high value product, madder growing attracted “adventurer farmers”. It is hard today to imagine farmers being put into the same class as gold prospectors but the potential returns on investment were such that many amateurs were drawn in. Of course many of these inexperienced adventurers were doomed to failure. What seemed like a shortcut to riches and fortune soon turned into a nightmare as old seeds sold by unscrupulous traders failed to germinate or the crop simply failed to grow well or any number of other disasters befell the hapless farmer.

Recipes from History

Contained in the text are numerous recipes for the processing of madder and dyeing of various fibres and textiles. These recipes are often quoted without interpretation into modern terminology so often remain obscure. However, they do offer a fascinating window into historical techniques and a platform for modern attempts to duplicate them.

Historical texts referred to:

The Leyden and Stockholm papyri (a Greek/Egyptian document written around 300AD which contains many recipes for the dyeing of fibre some of which use madder), e.g. :-

  1. Dyeing in Rose Colour  Rose colour is dyed in the following way. Smear the rolls of wool with ashes, untie them, and wash the wool in the liquid from potter’s clay. Rinse it out and mordant it as previously described. Rinse it out in salt water after mordanting and use rain water (which is so) warm that you cannot put your hand in it. Then take for each mina of wool a quarter of a mina of roasted and finely pulverized madder and a quarter of a choenix of bean meat. Mix these together by the addition of white oil, pour it into the kettle and stir up. Put the wool in the kettle and again stir incessantly so that it becomes uniform. When it appears to you to have absorbed the dye liquor, however, brighten it by means of alum, rinse it out again in salt water, and dry it in the shade with protection from smoke.

The Plictho of Gionaventura Rosetti: Instructions in the Art of the Dyers Which Teaches the Dyeing of Woolen Cloths, Linens, Cottons, And Silk by the Great Art As Well as by the Common (1548)

RED Madder wool-spinning-small

Rubia tinctorum

Growing Madder

An article by Ashley Walker
© copyright 2017

Common Madder (Rubia tinctorum) is an excellent source of red dye. It is indigenous to Southern Europe, Middle East, Central Asia and North Africa but has many close relatives (in the genus Rubia) around the world.

Rubia tinctorum

Young madder plant

Propagation, Care and Maintenance

As a herbaceous perennial, Common Madder dies all the way back to the soil at the end of every year. This means that madder beds can be mulched over the winter to suppress weeds and protect the soil from nutrient loss. Mulching with well-rotted manure or other soil improvers will have the added benefit of fertilising the soil.

Rubia tinctorum

Shoots of madder in the early spring surrounded by the dead stems of last year’s growth

Madder shoots appear in March and will withstand mild frosts. They grow into a mass of long clambering stems which need support to grow above a foot or two in height. Madder will tolerate coastal conditions of wind and salt and is highly resistant to pests and diseases. Seedlings will benefit from protection from slugs, but the shoots of mature plants need no protection. Growth can always be improved with a little fertiliser and watering in hot dry weather but we generally leave our madder to fend for itself and it still gets good harvests. The green part of the plant contains very little dye stuff but was used as animal fodder and reportedly would turn their bones red over time.

Growing Common Madder requires considerable investment from the dye plant gardener. From seedling or cutting it takes three to four years before the roots have swelled to provide a satisfactory harvest. Time is not the only consideration either. The plant is highly invasive and if neglected it will spread to the rest of your garden. The plant’s main method of propagation is the underground stem which grows horizontally under the surface and pops up one to three feet away. If you are a diligent (and ruthless) gardener you can keep on top of it by pulling up the shoots every time they reappear. Our approach is to set aside part of our vegetable allotment for madder. We remove stray roots as and when we dig the vegetable beds over. In ten years we have only once had to take more drastic measures when the madder was heading for the neighbour’s allotment. Madder roots and shoots are relatively thick which makes them easy to remove when digging; keeping the plant under control is far easier than dealing with perennial weeds like bindweed and couch grass. If you have no ‘out of the way’ space suitable for madder and you maintain an ornamental garden, madder can be grown in a large raised bed with deep walls to prevent the underground stems from escaping or, failing that, a very large planter. Setting up a separate raised bed each year for four years would allow you to harvest madder every year. The larger the container or raised bed the better. As with all container gardening, the plants will need extra attention to watering and feeding compared to madder grown in open ground.

Rubia tinctorum

Green berries of Common Madder

Rubia tinctorum

Madder berries turn from green through red to black. Although the black berries produce a wonderful red juice it does not appear to be a useful dye.

Madder also propagates itself by seed. The seed of Cleavers (a close relative) is covered in tiny hooks which attach to passing animals. With Common and Wild Madder the large seeds are surrounded by a juicy black berry which is eaten and spread by birds. Madder seed once dried is notoriously difficult to germinate. Many sources suggest that it will self-seed readily in some countries but we have never come across a seedling in our allotment. All of our madder beds were derived from a single seed we managed to germinate many years ago. So if you know someone who is already growing madder ask them for a root cutting from the underground stems in the spring and you may save yourself a lot of time.

Note: If growing from seed I previously recommended using advice from a scientific paper [1] which had found that soaking the seeds in very hot water for a few minutes would help break the seeds dormancy but having tried it ourselves I can categorically withdraw this advice. DO NOT DO IT! All I managed to do was kill the seeds! I will be writing up the results of this experiment soon.

With its scrambling habit and close resemblance to cleavers, most people would not judge Common Madder an attractive garden plant. However, if weeds are kept at bay, large beds of madder produce beautiful clouds of tiny yellow star-shaped flowers in July/August and glossy black berries in October. Providing support for it to clamber over also improves its attractiveness.

Rubia tinctorum

Rubia tinctorumRubia tinctorum

Rubia tinctorum

Harvesting Madder Root

Rubia tinctorum

Underground stems (Rhizomes) and true roots

There are two main types of root: bulbous true roots and straighter underground stems or rhizomes.  Once established, the adventurous rhizomes soon start to swell and take on some of the characteristics of real roots. They begin to produce and store the various substances that bear pigment. Both true roots and new plant shoots grow from these rhizomes. The bulbous true roots are the most prized by dyers but three year old underground stems can be just as good so do not discard them.

Rubria tinctorium

The bright orange shoots are new growth stems.

Rubia tinctorum

Network of underground stems just under the surface.

Rubia tinctorum

Cut underground stem, note the orange woody ring with red center of pith.

Rubia tinctorum

Cut root with thin woody centre

Having to dig up the root is often cited as a barrier to growing Madder, particularly if the soil in your garden has a lot of clay but there are many ways to make the task easier. If you do have heavy soil invest in several bags of soil improver and a few bags of sand and dig in well before planting. If that sounds too strenuous, create a “no dig” bed and spread over it a very thick layer (at least one foot or thirty centimeters) of a mixture of manure, soil improver and sand. Top this up in the second or third winter. It is true that madder roots will go very deep (several feet) into the ground but there is no need to dig down that far as most of the roots, including the largest ones, are usually near the surface.

Rubia tinctorum

Root stems and rhizomes before and after washing. With a little gentle brushing the outer surface of bark (which contains brown dyes) can be removed to reveal the orange flesh of the root. The difference between root stem or rhizome and true roots is seen here . Root stems are invariably straight and have a woody ring with red pith centres. True roots are twisty and have a thin woody centre.

Rubia tinctorum

Soil type is not important to the health of the plant but growing madder in an alkaline soil stimulates the production of the red dye stuff. We are fortunate to have a light chalk soil in our garden which is already quite alkaline. For acid soils an application of lime will improve the dye yield.

The general consensus is that the best time to dig Madder in Northern Europe is late Autumn, after the roots have been replenished by a full season’s growth. The worst time to harvest is Spring when all the nutrients are coming out of the roots and going into new growth. However, we have harvested at all times of the year and found that the results are  similar so don’t be too constrained by the literature. Of more import is what you do with the roots after harvest.

Rubia tinctorum

Mature madder root

Rubia tinctorum

Once removed the outer bark reveals the translucent orange flesh. The central woody core can be seen here through the root.

Rubia tinctoria

Washing the roots with a jet of water

Root Processing

First they need to be washed to remove loose soil. This can be done with a hose connected to the mains and the spray head set to a narrow jet.

We leave the wet roots to drip dry outside in net wash bags and then move them to a warm, dry place out of direct sunlight where they will get plenty of air circulating around them. It takes around one to two months to fully dry the roots, when they can be snapped by hand or chopped up for storage in air tight containers or paper bags in a dry place. Slow drying followed by long storage allows more of the precursor substances in the root to be converted into alizarin which is the substance that gives the classic pink/red. The root is admittedly easier to chop when fresh but then much more difficult to dry unless you have access to a herb dryer.

The clean roots can be used immediately but remember that most dye recipes specify quantities for dry root. Our experiments show that drying reduces the weight by a factor of six. So rather than 50% weight of goods you will need 3 times the weight of goods in madder. Fresh root is also useful for dyeing cloth in eco-bundles.

Rubia tinctorum

The dried root is chopped up for final storage.

Although it involves more work and considerable patience, we much prefer to dry the roots and keep them for a year or so before use. Indeed we think that along with our chalky soil and hard water, this may help to explain our success in achieving very good reds from our home grown madder.

Other red giving plants for your dye garden

It could be argued that Common Madder, being so easy to grow and yielding a great deal of pigment is the only dye plant in the UK worth growing for reds. However why should we limit our plant dye and botanical knowledge in this way? There are a number of related plants which have played an important historical role where soils are not well suited to Common Madder. While it is against the law to uproot any wild plants, many of these can be easily grown from seed and some are available from wildflower nurseries. Examples include Field Madder (Sherardia arvensis), Wild Madder (Rubia peregrina), Lady’s Bedstraw (Galium verum) and Dyer’s Woodruff (Asperula tinctoria). Wild Madder appears very similar to Common Madder but is evergreen and grows wild in South West England and South Wales. Lady’s Bedstraw is a lovely perennial wild flower with dense clouds of yellow flowers in July and August and surely deserves a place in the dye garden?

Rubia Peregrina

Wild Madder (Rubia peregrina) found growing in a hedgerow near Brixham, Devon 2nd Jan 2017. Photo by Brian Bond.

It is said in the literature that these relatives of madder do not provide as much colour as Common Madder, primarily because the plants are harder to harvest and the roots are thinner. Even the common weed, Cleavers or Goosegrass (Galium aparine) is said to contain similar pigments to Common Madder although its thin roots are unlikely to yield enough for true reds.

A further article based on the book “Madder Red” by Robert Chenciner will be posted later in the spring when I’ll be looking at the history of growing madder and its lessons for the craft grower.

Bibliography

Ecotone Threads (another really good blog post on growing Madder by Kori Hargreaves in California).

Chenciner, R. (2000) Madder Red: A history of luxury and trade Curzon, Caucasus World

Sandberg, G. (1996) The Red Dyes: Cochineal, Madder and Murex Purple, Lark Books

Cardon, D. (2007) Natural Dyes, Sources, Tradition, Technology and Science, Archetype Publications London

[1] Sadigheh, S. et al (2009), Study Methods of Dormancy Breaking and Germination of Common Madder (Rubia tinctorum L. ) Seed in Laboratory Conditions, Botany Research International, 2 (1): 07-10  See http://www.idosi.org/bri/2(1)09/2.pdf

Reseda luteola

Growing Weld

An article by Ashley Walker
© copyright 2016

Weld or Dyer’s Rocket (Reseda luteola) is a UK naturalised biennial wild flower that prefers to grow on chalk or limestone soil. It has pale yellow flowers and can grow to over two metres in height in its second year. The adult flowering plants are often seen growing in great masses on waste land or recently disturbed ground and may then mysteriously disappear only to pop up somewhere else another year. It has one common close relative, Wild Mignonette (Reseda lutea) which can also be used as a dye plant. Sweet Mignonette (Reseda odorata) is a closely related plant from the Mediterranean often grown in gardens for its attractive scent and as a bee attractant. All of these plants are well known for their perfume which is particularly noticeable when the plants are dried.

Weld is a Biennial

Reseda Luteola rossette stage

Two Weld rosettes in early spring

As a biennial, Weld is usually expected to grow from seed into a “rosette” in the first year. A rosette is a ground hugging form, where all the leaves grow from a central point. The plant  goes through the winter as a rosette, when there may be some die back during cold frosty weather. In the Spring the rosette grows new leaves and the central stem starts to emerge into a tall flower spike. Once flowering is over the plant is expected to die. Well that’s the official line, but anyone who has grown biennials will know that it all depends on how the plants are grown (see photo).

Reseda luteola

Above, large Weld rosette in October it has tried to put out a flower stalk but the shortening day length has stimulated it to return to its rosette stage. Below, Weld in full flower.

Reseda LuteolaLeft to its own devices, weld seeds get scattered from mid-Summer onward. Some of these seeds will fall to the ground and germinate during late Summer and Autumn and grow into rosettes as expected. Other seeds will lie dormant in the soil and await an opportunity to germinate, usually afforded by a disturbance to the soil (animals rooting about for grubs or roots or a gardener tilling the soil). These seeds will take their chances to germinate at any time of year when the weather is warm enough. Some seeds will germinate in early Spring and, if the conditions are right, may complete their entire life cycle in one year. If the plants are stressed for any reason e.g. by drought or physical damage, they are even more likely to flower. The later in the season the seed germinates the more likely it is that it will flower in the following year. Weld’s rather random flowering behaviour makes it an awkward plant to cultivate. It is also highly sensitive to any kind of root damage, so transplanting seedlings invariably results in numerous casualties and transplanting an adult plant is almost impossible. It is quite often the case that the best plants the garden grows are those that have self-seeded in a path or on the vegetable patch – in fact anywhere except the bed you have set aside for growing Weld! It is not for nothing that Weld is generally regarded as a pioneer plant – one of the first to colonise waste ground.

Propagation

Reseda luteola

Tiny round black seeds of Weld

The gardener interested in growing Weld for dyeing will seek to grow as large a plant as possible. This means allowing the rosette plants to build up good food reserves in their deep tap roots before shooting that ‘rocket’ of a flower spike up into the sky. This requires a certain amount of garden pampering and a choice of strategies.

Strategy 1

Reseda luteola

Reseda luteola

The same bed about two months apart. On the left the weld seedlings have been planted for a week or two and the leaves have turned brown. Two months later many of the plants have died.

Sow seed thinly into modules in early April under glass or indoors. Do not cover seeds with compost as light helps them to germinate. When the plants have grown to around the five to ten leaf stage, carefully plant out into prepared beds in mid-May. Do not add any fertiliser to the soil as research shows dye yield falls with increased nitrogen, but do water as needed. Continue to water the young plants, particularly in hot weather, and weed throughout the year. With luck, some of the plants will grow large and flower in mid or late summer when they can be harvested.

Reseda luteola

Close up of struggling Weld seedlings

Strategy 2

Sow seed thinly into modules in late August and plant out carefully when large enough and water regularly, particularly in hot dry conditions. Allow to grow and go through winter and they will flower in June/July the following year.

Strategy 3

Reseda luteola

Self-seeded Weld with a few Dyer’s Coreopsis plants I planted in the gaps to brighten the bed up a bit.

Obtain some seed heads from wild Weld and scatter the seeds in great quantities directly onto prepared beds in spring. Keep beds watered and weeded. Scattering a few organic approved slug pellets will help to protect the young seedlings which may or may not germinate.

Reseda luteola

Mature flowering plants in the background and first year rosettes growing in the foreground.

Now if this all sounds a bit hit and miss, it is!  When I grow the seeds under glass or indoors I certainly get excellent germination but lose many seedlings on planting out. Enough, however, survive to produce adult plants some of which I allow to set seed. If this is done over several years the seeds accumulate in the soil and self-seeding will start. Note: to stand any chance of self-seeding the soil must be kept bare i.e. free of weeds and any kind of mulch (mulch suppresses seed germination and harbours slugs and snails). Remember, Weld is a pioneer plant and does not like competing with vigorous perennial weeds. Small rosette plants can be moved from inconvenient positions if carefully dug out with a large clod of earth around the roots.

Mass Planting

Weld does not make a particularly attractive garden plant in its rosette stage but if grown in ‘mono-culture’ it can put on a surprisingly good show when it flowers. If there are gaps in the first year Weld bed you can interplant other dye plants for added colour. Coreopsis is particularly good in this respect as it is an annual.

Reseda luteola

Mass planting of Weld

Harvest

Reseda luteola

Weld harvest

Right, dried Weld and Left, freshly harvested Weld being cut up ready for dye extraction.

 

 

 

 

 

 

 

 

 

Harvesting the plants just after they begin to flower in June is generally considered the best time. As the leaves begin to die off the amount of yellow dye starts to diminish, however, dyestuff can be obtained from the rosette leaves and from old plants that have finished flowering. All parts of the plant except the roots yield dye, including the stalks. Weld plants can be very big and take up a lot of storage space. If the plants are hung up to dry somewhere warm, dry and dark they will remain green, but if dried in the light they will turn a straw yellow or even bleached white. They will however still give good dye colour. Once dried the plant can be chopped up to save on storage space and kept in boxes, bags, storage jars etc. in a dry place.

Harvesting from the wild

Weld is often found growing on waste or disturbed ground, road verges and rail cuttings, so it is not that likely that anyone would complain about people picking it. However, the law is clear “it is illegal to uproot any wild plant without permission from the landowner or occupier. Uproot is defined as to dig up or otherwise remove the plant from the land on which it is growing, whether or not it actually has roots”. Occasionally we do harvest from the wild but we always try to be responsible by cutting the plant stalks (not pulling up the roots) and leaving plenty of plants to seed.Reseda Luteola

Persicaria tinctoria

Growing Japanese Indigo

An article by Ashley Walker
© copyright 2016

Japanese Indigo, Persicaria tinctoria or Polygonum tinctoria is a frost tender member of the knotweed family. Originally from China and Vietnam it likes to grow in warm moist climates, often as a waterside plant. Our closest relative in the UK is Common Bistort or Persicaria bistorta which closely resembles Japanese Indigo but has no trace of indigo in its leaves (I did try once) though it does give a pleasant orange on alum mordanted material. Japanese Indigo will grow from seed to flower in one season and, if it does not get frosted, is capable of growing into the second year though here in the UK getting a plant through the winter is very difficult even indoors with extra lighting. We grow Japanese Indigo because it gives more indigo than Woad (approx. double the amount) and the colour is generally cleaner and more predictable than Woad.

Varieties of Japanese Indigo

There appear to be two distinct varieties though I have not seen anyone put a name to them.
See comparison here.

Three strains of Japanese Indigo tested and observations on indigo extraction

Persicaria tinctoria

Pointed Leaf Japanese indigo

Pointed or long leaf Japanese Indigo. This is grown as an indigo dye crop in Germany and has probably been selected for its ability to grow in a northern climate. It is a more robust plant tolerating colder weather and flowers much earlier. It has pale green occasionally pinkish stems and white or pink flowers which grow on elongated flower stems. The leaves are large narrow and pointed.

Persicaria timctoria

Broad Leafed Japanese indigo

Broad or rounded leaf Japanese Indigo. This is the variety most commonly grown in gardens, perhaps because it produces a profusion of pretty deep pink or white flowers. Its stems are thick and also have a tendency to be pink. It seems less adapted to a northern climate and in poor weather struggles to grow – when first planted out, the leaves often go pink or yellow at the tops of the stems and continue like this if growth is slow. When grown in a greenhouse or polytunnel however the plants are greener, although I have not noticed any difference in indigo production between the two, (see link to article on comparison of three different strains above).

Persicaria tinctoria

Comparison of Broad leaf and Long leaf Japanese indigo.

Growing Japanese Indigo

Persicharia tinctoria seedlings

Some of my seeds are “tricotyledons” and these germinate with 3 baby leaves rather than the usual 2. This is an uncommon mutation and may be a sign of inbreeding.

The shiny black seeds have only a short life (about a year if stored in a cool dry place). They can be frozen in the freezer and will last longer. To freeze the seeds first dry on a windowsill then place in a sealed plastic bag with a packet of silicon desiccator for a few weeks then pop in the freezer. Note: seeds frozen in this way tend to germinate slowly and may take up to 5 or 6 weeks to germinate. Commercially bought seeds are often stored frozen so don’t be too alarmed if you get no germination’s in the first 2 weeks. Interestingly I tried drying some seeds with a hair dryer on a low heat setting from a distance and found that this treatment also put the seeds into a deep sleep.

So, using some fresh seed grow in heated seed trays indoors from early April or late March. Sow thinly and cover with a thin layer of compost. Once germinated try to give them as much light as possible as they will grow “leggy” if kept on an average windowsill. The seeds should germinate readily within two weeks but occasional seeds may not germinate for a month.

Persicharia tinctoria seedlings

Seedlings with secondary leaves at around 4 weeks

The plants are very robust and rarely succumb to disease or pest, they will also transplant readily and can be pricked out at an early stage and potted up if you wish to do this. I usually leave them to grow in the tray until I am reasonably sure there will be no more frosts. Here in Hertfordshire that’s usually around the 6th May. By this time the plants will be quite large and the trays root-bound, some of the plants will have put out secondary roots from the stems and rooted in more than one place. Separating the plants out is therefore difficult and it is best to soak the tray in a bucket of water before trying. Do not worry about breaking the roots as Japanese indigo will re-root itself with ease. Planting in May is only advantageous if the forecast is for warm and sunny weather. If the forecast is for cold overcast weather wait until June before planting out.

Dye plants waiting to be planted out

Trays of dye plants waiting to be planted out including some root bound Japanese indigo.

Persicharia tinctoria

These plants stayed much the same size for 2 months before finally starting to grow in August of 2016

Persicaria tinctoria

These Japanese indigo plants show a typical growth pattern when planted on mass with the larger plants towards the middle and smaller plants at the edge.

Weather is critical for good plant growth as you must remember this is a semi tropical plant. Sometimes the weather never really becomes ideal, in the cool dark summer of 2012 the plants grew hardly any larger than when I put them out. The plants were pale and looked sickly and there was no harvest. This year (2016) many of the plants also grew very slowly because the weather in the early part of the season was cool, wet and cloudy. It was not until late July when the weather improved that they really started to grow. If you have plenty of seedlings you can plant them about 4 inches apart in a heavily manured soil. Both Woad and Japanese indigo require lots of feeding to get a decent sized plant. Manure is the best if you can get it, but other fertilizers will do. Soil type is not much of an issue and the plants will grow on any soil. Clay loams are probably the best. My plants are grown on a poor chalk soil and I have problems with some nutrients in the soil being used up very quickly. Crop rotation is important for me as the plants do not seem to grow well if planted in the same area as the previous year. All my indigo beds need to be given a second feed in August particularly if I cut a first crop and allow the plants to regrow. Even so, many plants regrow with yellow leaves indicating they are short of some vital nutrient.

Rows or Beds? – I mostly grow indigo in beds on mass simply because I have limited room in the garden. Every year however, I notice that the plants at the edge of the beds grow weakly and the plants in the middle are the largest of all. I do not know the reason for this but speculate that the plants thrive best when in competition with each other or there is some symbiotic relationship which allows the plants to benefit each other. I am inclined to the former as the plants also tend to grow larger when in competition with entirely different species. Either way I also speculate that growing the plants in rows is not ideal as the plants are not as close to each other.

Persicaria tinctoria roots

Roots grow readily from the stem nodes.

Propagation via cuttings – If you only have a few plants and want to grow more from cuttings you are in luck as Japanese indigo is one of the easiest plants to grow this way. Just cut off the stems from about 6 inches above the ground and place in a container of water. New roots will grow immediately from the stem nodes and the cuttings will be ready to plant out in two weeks. Alternatively just stick the cuttings directly into the ground and water well (each day in hot weather) until the new plants are established.

 

Problems

Overfeeding – I used to think that it was impossible to overfeed Japanese indigo but in the summer of 2017 I did overdo it a bit with some fish, blood and bone fertilizer which is particularly concentrated. The plants can become scorched, deformed and yellow. Initially the damage looks very much like early frosting as the leaves die off, turning the characteristic gray blue. Later the surviving leaves turn yellow and can become deformed. If they survive they will eventually recover without any lasting problems.

Persicaria tinctoria

Early leaf damage due to over feeding with Fish, Blood and Bone fertilizer.

Japanese Indigo

Yellowing of leaves due to overfeeding.

Persicaria tinctoria

Weeks later plants still showing damage – stunting with deformed and yellowing leaves

 

 

 

 

Under-watering – Easily done if you go on holiday or just forget during hot sunny weather. Once again the effect on the plants is similar to frosting and overfeeding.

Frost Damage – After the first frosts of the Autumn the upper exposed leaves are usually damaged first and turn a dark blue-gray. The indigo has become fixed into the leaf and can only be extracted if the leaves are placed in a reducing dye bath. (Reducing agents are fructose, spectralite (Theourea dioxide), sodium dithionite or a fermentation bath).

Persicaria tinctoria

Early Frost damage on Japanese indigo showing characteristic blue gray areas where the plant tissue has died.

 

Maintenance and harvest

As a waterside plant Japanese indigo is used to having its roots in water and it follows that it will grow very poorly in dry well drained soils. In the summer months of June to August I have to water my plants nearly every day because I have a light chalky soil. Once the plants achieve total ground cover they act as a shade and help keep the soil damp but they still need water on a regular basis.

Persicaria tinctoria

Take the first cut about 8 inches above ground leaving plenty of leaves on the plant.

In experiments growing some Japanese indigo amongst other plants. I was surprised how well it responded to the competition, growing taller and greener. In a good year it is possible to take two or even three harvests of the plant. The stems are cut about 6 to 8 inches above the ground and the plants soon grow back.

For an added boost to your harvest once you have stripped the leaves off the stems the now leafless stems can be placed in buckets of water with a dollop of liquid fertilizer and they will grow quickly back. The stems alone have no indigo content.

Persicaria tinctoria stems

Stems of Japanese indigo after leaves have all been stripped off.

Persicaria tinctoria

The stripped stalks when placed in buckets of water with added liquid fertilizer will rapidly regrow and provide you with an extra harvest.

Indoors or outdoors and growing for seed

Persicaria tinctoria

Growing in a greenhouse it was possible to plant the seedlings out earlier but even then a mild frost in early May damaged and killed some of the plants.

 

Persicaria tinctoria

Frost damaged seedling in the greenhouse in May 2016.

Persicaria tinctoria

 

 

 

 

 

 

 

 

 

 

Persicaria tinctoria

Persicaria tinctoria

Japanese indigo does not need to be grown in a greenhouse or polytunnel unless you live far to the north but it clearly prefers being indoors growing lushly with greener, larger leaves and does not produce flowers until later so has a longer season.

 

 

 

 

 

 

 

 

Japanese indigo needs a long growing season to flower and usually only comes into full flower in October. It is self-fertile so will produce seed in a sealed greenhouse but will flower sooner outside in full sun. However, If frosts or bad weather are forecast before the seed has set be ready to dig a few up and transfer to greenhouse or poly-tunnel or bring indoors in pots. In the North it may be best to grow Japanese Indigo in a greenhouse or poly-tunnel. But because it flowers later it may not be possible to get seed unless the greenhouse is heated.

Some growers have reported that it is possible to get plants through the winter by bringing them into a well-lit and warm area where they will flower early the following year and produce seed.

The different varieties of indigo respond differently to greenhouse growth as the photo below shows. This particular variety flowered at much the same time in or out of the greenhouse. The leaf curl may be a response to the extra heat.

Persicaria tinctoria

The long leaved variety growing in the greenhouse with curled leaves.

Persicaria tinctoria

This miserable looking plant flowered in June and as you can see has been highly stressed with stunted growth and pale leaves with a pinkish blush

Persicaria tinctoria flower with honey bee

There are always a few plants that come into flower before the rest and it is best to leave these alone when you harvest. A few years ago I began an experiment to try and breed a variety of early flowering plants so I could be sure of getting some seed even in a bad year. This went according to plan and I ended up with plants that flowered in early September and some in August. However, once the plants start to flower the amount of indigo in the leaves starts to reduce and in full flower the yield is very poor. This led to lower harvests overall. Another strategy you can use for getting seed is to grow a few plants in a dry bed only giving them enough water to keep them alive. These plants will become stressed and will flower earlier – they may look miserable but the seed will produce nice healthy plants next year. Interestingly when the plants are in full flower they are very attractive to bees particularly honey bees. I wonder if honey can be obtained from the German fields of Japanese Indigo, as is possible with the fields of Woad in Norfolk.

Persicaria tinctoriaPersicaria tinctoria seed

Persicaria tinctoria

Seeds from the flowers in the greenhouse. As bees and most pollinating insects could not get into the greenhouse it looks like the the flowers are self fertile.

When the flowers go brown they can be cut and hung up or laid out to dry and some of the seed will fall out. The remainder can then be rubbed out. Separating the seeds from the “chaff” is a skill all by itself. Once you have removed the seeds and dried flower material from the stalks, place the whole lot in a tray and shake from side to side. All the heavy seeds will settle to the bottom and if you are careful you can blow the chaff from the top. This can be a dusty business so you must be careful not to breath it in. Some of the seed will retain an outer layer of brown chaff bound to the seed; this does not impair germination.

Persicaria tinctoria direct dye

Take a few handfuls of leaf and crush them up in a suitable container or blender. Add some white fibre immediately to the mix and leave for an hour. The colour obtained is rather dull and some of the colour may wash out. What remains will be fast and will give you a good indication of how good your indigo is.

When new to dyeing with Japanese Indigo and Woad it is common to wonder how indigo was discovered as the plants apparently do not produce anything obviously blue though occasionally leaves will die and turn a dark grey or blue black. I suspect that someone observed that when crushed the fresh leaves will release indigo but it is only noticeably blue if you then add some white fiber to them. This is a good test to see if your indigo is ready to be harvested.

Persicaria tinctoria

The broken leaf has turned bluish black