Growing Madder Plants in Containers

Looking back to 2013, when I first sowed madder seeds, it was a good job the plants went into a raised border by a wall. Since then I've discovered that planted anywhere else in my garden, madder plants dwindle away and die in the wet winters with barely a red root to show for their sad existence. Because the first plants flourished in the relatively dry conditions of extra height for drainage in the rain shadow of the wall, they flowered and set seed from their second year onward. After three years, I dug up most of the original plants to make madder root dye. Thanks to the seeds they supplied, many of their offspring still live on.

Sown a centimetre deep into small pots of damp compost in March, I find at least half the seeds saved in autumn will germinate at room temperature and grow on strongly in an unheated greenhouse through April. I must have planted out dozens of little madder plants each May since 2015 and while the ones in garden borders didn't survive, plenty of others have managed ok in containers and their roots have made great contact prints.

From the perspective of the prospective dyer, the true measure of how well a madder plant is doing is hidden under the earth. Last summer, plants in their second year were waiting in plastic pots, some outdoors and some in the greenhouse. From August onward, the greenhouse went unwatered. It is only lately I have faced the sorry sight of dead brown plants.

Madder naturally dies back to the ground in winter, leaving only tough, dry stems. To my great delight, when I tried to pick up the line of madder pots in front of the grow bags, I found they had grown substantial roots through the bottom of their pots to get to what little moisture there was in the gravelly soil below. Forking through the gravel, I even found a surprise harvest of madder roots.

The plastic pots outside got the benefit of rain to water them, yet they have no sign of roots coming through their holes. It seems that once established, madder plants grow more roots the less water they get, even to this extreme. The greenhouse is now cleaned and patched up for the spring and those madder plants are staying inside, potted on into the biggest pots I have - with one good watering to help them over the shock.

Size does matter. This terracotta pot is bigger than a bucket and last June, it contained a madder plant starting its third year. The scrambling stems were taking over the pathway with tiny hooks that catch on clothes. Once turned out, although the mat of yellow fibres on the outer surface suggested the pot would be crammed, the internal root harvest proved less dramatic.

Below its crown, this two year old plant had long roots going down through the earth to a fine network at the base .

Six other madder plants that started at the same time, in spring 2015, have been growing in an old water butt with its top sawn off. This is how they looked last March, with new shoots just appearing. Summer brought the usual tangle of foliage flopping over the sides, probably less per plant than was sprouted out by the lone madder in its terracotta pot.

Realising these were now exactly three years old, I decided to find out how well conditions in a 50 gallon wooden container had suited them. Last weekend, braving freezing winds, I spent all afternoon emptying out the entire barrel. After chiselling out the dormant crowns, hopefully with enough roots attached to keep them alive, I dug down layer by layer.

All the soil was dry and friable, easy to shake off. There were yellow shoots as well as big red roots near the top. Deeper in, many thick roots ran all the way down to a riot of yellow rootlets encasing the broken bricks which filled the base. The soil at the bottom was the only damp area and it was finger numbingly cold to sift through, time to go indoors and warm my hands on a mug of tea.

The following day, I stayed in the kitchen for a massive root rinsing exercise. The wet weight of the madder barrel harvest was 2.7kg. The clean roots have been laid out in the spare bedroom on towels to dry and I expect the final weight of madder to store will reduce to only a few hundred grammes. Still, I have read that the alizarin red dye the dry roots contain actually improves after keeping them a couple of months.

All this leads me to conclude that on a clay soil in rainy South Wales, the best madder root harvest comes from planting in the deepest possible, porous container and not bothering to water it once the young plants are established. My plan for the spring is to buy two big wooden wine barrels, drill several holes in their bases, add plenty of crocks and bricks to help drainage and set them alongside the old water butt on raised plinths in the front garden, where they will get the afternoon sun.

I think I shall do just as I did with the original water butt, half fill them with rotted sheep manure, add some handfuls of wood ash to alkalinise the soil and top up with compost. With a bit of luck, replanting two big crowns into each of three barrels will mean much faster root growth than starting with new seedlings. Though the weather is savagely cold, here is a picture of May to remind me how fast the garden will soon be changing. 

Today was a good day for putting on a sheepskin coat, walking the dog in the snow, thinking about the story so far, for garden planning and for dreaming. How very nice it is to be retired, not to have to struggle in to work, but light the fire and stay indoors.