By Ashley Walker
Copyright Natures Rainbow. April 28th 2021

Over 3 years ago we made a large container (planter) from pallet wood and planted two Common Madder (Rubia tinctorum) plants, Lady’s Bedstraw (Galium verum) and Dyer’s Woodruff (Asperula tinctoria). Our plan was to see if madder grown in a deep planter would differ from madder grown in the ground. We also wanted to see how these three plants would  grow together. One of the madder plants was from a cutting obtained from the Southwark Cathedral Dye and Herb Garden, and looked a little different to the form we grow.

After growing for three years, our first conclusion is that madder is probably best grown on its own because it substantially outcompetes the other plants and the roots become entangled. By the end of the third year there were only a few tufts of the Lady’s Bedstraw and Dyer’s Woodruff left at the edge of the container.

See this short video of the harvesting process. Many apologies for the very poor quality of this video. We have yet to learn how to film properly from our digital SLR camera. Also we are in an urban setting and the sounds of daily life abound.

I have to say that I found the experience of getting the root out of this container almost as difficult and strenuous as digging it out of the ground, so I am going to change my advice to other growers and recommend that they carefully choose the sort of container they use. I don’t recommend planting in the very largest container you can find; better to choose a medium sized one or a large container that can be dismantled easily. A stack of tyres or a patio planter designed for potatoes might have been better. The main difficulty of harvesting the root from the container was not sorting through the soil but creating space to do the sorting followed by tidying it up afterwards. Down in the dye garden there are no such worries.

Differences between growing Madder in a container vs in the ground

In the ground

1. Madder is invasive and over many years will invade other parts of your garden, or worse your neighbour’s garden! Although to be fair, madder takes many years (at least 6 to 10 years) before it starts to cause a real problem and the average gardener will find it much easier to control than many weeds.
2. Because it is allowed to “roam free” it produces a lot of underground stem rather than true root. (Note: a three year old stem has just as much dye as true root, however, underground stems are not produced until the plant has started to mature).
3. Although most of the root is to be found in the top 12 inches (30cm) of soil, the root can penetrate deep into the ground (one or more metres) so that harvesting is unlikely to extract every single piece of the root.
4. Apart from occasional droughts, the madder does not need much watering.
5. In the first year weeds can be a problem but once established a bed of madder is relatively maintenance free.

In a planter

1. The plant produces much more true root than underground stem.
2. The planter needs to be watered frequently during the summer and if the container is small to medium sized you will probably need to make arrangements to have it watered if you go for a long holiday.
3. Harsh frosts during the winter can kill madder in a small container above ground if it is in an exposed location. So depending on your climate you may need to protect your planter or bring it indoors.

These are the characteristics I can be certain of. Other interesting differences of the container grown Madder that we noticed were:-

1. The roots were generally thinner than roots grown in the ground.
2. The roots from the planter were darker in appearance and a duller colour (we have yet to test dye from them). The different colour may be due to the type of soil in the compost. Our local soil is chalky and alkaline but the planter soil was probably slightly acidic, being a mix of clay soil and commercial compost.

Yield

Overall we obtained just over 2kg of fresh root from the planter (dimensions 1m x 55cm x 50cm). This works out as approx 330g of dried root which is about a sixth of the weight of fresh.

Conclusions

The reasons for growing in a container:

1. Concern about your plants becoming invasive
2. Lack of growing space
3. Keeping madder separate from your other perennials. If they interpenetrate it is hard to harvest the madder without damaging your other plants.
4. Ease of harvest

Of these reasons I will now strike out number 4 and advise people with limited growing space to grow in smaller containers or ones designed to be dismantled easily even though this may mean more maintenance. I would also advise people to be less cautious about growing in the ground but if you do decide to do so, keep the madder well away from your other perennials or place an underground barrier around the madder. Growing in the ground can be a lot easier!

Note from Susan: In summer and autumn the scratchy aerial parts of the mature madder plants in the planter scrambled over and through other patio plants. In our very small garden I found this annoying. I inserted supports to try persuading the plants to grow vertically instead. I also planted some daffodils in the container in the final autumn to cheer up the space when the madder was dormant in early to mid-Spring. This was seen as an act of sabotage!