An article by Ashley Walker
© copyright 2016

Dyer’s Coreopsis (Coreopsis tinctoria) Plains Coreopsis, Garden Tickseed, Golden Tickseed, or Calliopsis is an annual flower growing from one to two feet in height from the prairies of North America. It is very pretty with bright red and yellow flowers, now grown primarily as a decorative garden flower or as part of a “wild flower mix”. There have been several attempts to cultivate varieties better suited to the garden. I list some of the more successful cultivars below.

“Mardi Gras” – Suttons seeds
“Mahogany Midget” an all-red dwarf variety – Chiltern seeds
“Roulette” a semi-double variety – Mr Fothergills and Kings Seeds
“Quills and Thrills” a variety in which the petals form tubes – Thompson and Morgan
“Incredible” a mixed variety – Dobies seeds (contains seeds of a white and red petal flower)
“Radiata Tigrina” a jazzy variety – Chiltern Seeds
“Coreopsis hybrida Incredible Dwarf” – Kings Seeds

All of these varieties have been created by careful and rigorous selection and the resulting cultivars will generally breed true. However they will easily hybridise with each other if grown close together. For the novice the best of these may be the dwarf varieties which do not require support.

For several years we have been using saved seed, originally from a wild-type variety from Suffolk Herbs (now Kings Seeds).  This has produced a diversity of flowers, some almost identical to the varieties above. There is a huge natural variation in flower type which is passed on via cross pollination from year to year. The only named variety we have grown is “Roulette” which was not much different from the wild type.

Dyer’s Coreopsis is part of a huge genus of plants in the Asteraceae family, many of which have also been used as dye plants. Tinctoria is distinctive in having a large proportion of red in the petals, so perhaps most of the dyestuff is in the red pigment? In this case, pure red flowers would be the best for dyeing. The majority of our flowers are deep red with a yellow outer edge. Some are completely red. A smaller number are intermediate. I would like to know if the red petal colour contributes a different pigment, but as all the flowers have a yellow underside to the petals, regardless of the surface colour, this isn’t an experiment I can do easily. Coreopsis, like Dahlia, contains dye pigments not found in the classic yellow plant dyes of the European Medieval Petit Teint. These are called chalcones and aurones. For a note on the chemistry and history see Dominique Cardon, Sources Traditions, Technology and Science (2007, pp683,4).

Dyer’s Coreopsis is invariably described as “Perfect for pollinators” by the Royal Horticultural Society, however, we have not seen any evidence of this over many years of growing.

Propagation

Dyer’s Coreopsis is prone to slug and snail attack so is best sown into seed modules (two or three seeds per module) in April and planted out in May with organically approved slug pellets. Root damage during transplantation will stimulate the plant to flower prematurely so care must be taken. It is generally considered to be hardy and in some areas of North America can be treated as a biennial and directly sown in Autumn for a spring flowering the following year. We tried this in 2018 growing the plants in pots to help keep the slugs off. The results can be seen here.

There is great variation in habit, with some plants producing flowers early when the plants are small and others remaining as “rosettes” until late summer. Planting out early, after only a short time in the seed tray, will discourage early flowering. The plants will grow to a good size and give a much better display/dye-harvest. For spectacular displays plant seedlings close together (4 inches apart).

Here in Hertfordshire we rarely get any self-seeding (just the occasional plant) so we have to sow from saved seed every year.

Care and Maintenance

Faces to the sun
The flowers of Coreopsis all point south towards the sun, so in order to get the best display, grow them in a place where you can stand and admire them with the midday summer sun behind you. We usually plant these ‘en masse’ in a bed of their own. The photograph shows Coreopsis in a narrow bed alongside the southern edge of the greenhouse. In their natural habitat they get the support of other plants. In this location they would have benefited from some support to stop them flopping all over the path.

Dyer’s Coreopsis will grow in any soil type and does not require much fertiliser. Like Weld, it is best grown in rotation with Japanese Indigo or Woad. In the wild it likes to grow in damp places but prefers a well-draining soil. Coreopsis roots are shallow so the plant needs regular watering to grow larger and flower for longer.

Slugs have the habit of chewing through the main stem which usually kills or seriously delays the plant’s development. Apart from this they do not seem to suffer from other pests or diseases.

Seed Saving

Once the flowers have “gone over” the small rod-shaped black seeds start to mature. As a rough guide, the seed-heads will be ready for picking after a month. Bring them indoors to dry out completely. Rub the seeds out from the dried flower heads with your fingers into a shallow tray which can then be shaken from side to side and blown gently to remove the chaff. Stored in sealed bags and kept in a cool place, the seeds will remain viable for around three years.

Harvest

Before and after picking
Here you can see the same bed before and after picking. It took about half an hour to pick all the flowers in the above photos. A small footstool makes the job easier. It’s very calming to slow right down and enjoy the process. Only pick the flowers in full bloom, or those that have gone over. Leave the buds.  If you are in a rush, you can pick the whole plant, stalks and leaves included, but it is a terrible waste as the plants will come back into full bloom within a week.

Tools of the trade

We have a weakness for baskets. This is one of a set of five fairtrade baskets Susan bought from Oxfam years ago. They are perfect for flower picking. There’s no need for any cutting tools to pick the flowers. They pinch off very easily, but be careful not to pull them off vertically as the whole plant may come up with the flower.

We use a Stockli herb dryer which has served us well over many years. A fan in the base blows warm air up through a stack of trays. It’s well worth buying extra trays. We also use it to dry basil, oregano, rose petals and apple rings. Some flower heads, like Coreopsis, will dry in just a few hours but fatter flowers like Dahlia need a couple of days. To store well, herbs and flowers must be absolutely dry. Keep going until they feel dry to the touch. Then leave them for 24 hours in the trays in a dry place for any moisture remaining in the flowers’ centres to be drawn out. Then give them another short drying session (about an hour). This will reduce the risk of the flowers going mouldy in storage.

Make sure your container is truly airtight and store in a cool, dark, dry place. If you have done a good job the dried material can last for years.

Dyeing with Coreopsis

The dyes in Dyer’s Coreopsis are highly soluble, so all that’s needed is to pour on boiling water and leave the flowers to soak. Susan added the dyestuffs to the baths in two batches. The yarn and one silk/cotton swatch went in with the hot water at the start. These were left for several days, removed and rinsed. The paler coloured cotton drill, cotton jersey and the other swatch of silk cotton were left in the exhaust bath for 48 hours. Again unheated. The results tend to confirm Jenny Dean‘s note in her book Wild Colour, that there are at least two pigments in the flowers, a red and a yellow. The red is probably taken up quicker than the yellow, hence the orange tone (yellow+red) is restricted to the early phases of the bath. The exhaust bath only contains the yellow.

Here are some samples dyed with flowers dried in a previous year. The yarn is cotton mordanted with alum. The various fabric swatches were cold mordanted by a long soak in 5% aluminium acetate. All samples were photographed just after rinsing so the colours will lighten on drying

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