Silverweed has a long history as a cultivated crop. It was sufficiently important, in the landscape-scale agro-ecology of the pre-colonial Pacific North West, that access to good patches was controlled by law. Closer to home, Alexander Carmichael says in the notes to the Carmina Gadelica that silverweed root (brisgean) was much used in the Gàidhealtachd before the potato was introduced. He says that it could be traded, ‘quantity for quantity’ with corn and meal, suggesting that it was equally valued nutritionally. It was considered palatable and nutritious and eaten boiled or roasted or dried and ground into meal for bread and porridge. I mostly eat it boiled and find that it has a rich, creamy taste and texture.
One eye-catching claim made by Carmichael is that at Lag nan Tanchasg in Paible, North Uist, ‘a man could sustain himself on a square of ground of his own length’ by growing silverweed. Unfortunately he makes no mention of cultivation methods, but I suspect that he is talking about a lazy bed system, in which a raised bed is heavily mulched with seaweed. This would make sense both as a way of growing heavy yields of, well, anything, on Uist (and was later used there for growing potatoes), and also because silverweed is well adapted to growing on the seashore and is often found there. Like many species adapted to growing on shifting sediments, it spreads strongly via runners, which help it to bind the soil together and adapt quickly to disturbance. It’s a habit which has helped it adapt to other, novel habitats, such as the frequently-disturbed, heavily-salted margins of roads.
It’s also a habit which makes it, as anyone who has tried will know, difficult to replicate past cultivation methods in an ordinary garden. It will take over any veg bed it is planted in in short order. It will also naturalise happily in grass, but then it becomes very difficult to dig out the starchy roots which are its main edible part. A further complication, if anyone was really serious about adapting this plant to cultivation, is that it’s hard to maintain and breed separate lines of a plant that is hard to contain as an individual even in a pot, never mind in a patch of soil.
This might explain why, despite having been interested in silverweed ever since I first tasted its roots, I haven’t made much progress in fitting it into my garden. However, I did make one useful discovery recently which should make the task somewhat easier. I have a number of individual clones, collected from around the country, which I keep separate by growing in buckets (escaping from a bucket is nothing to this Houdini among plants, but you can thwart it by winding its runners around inside the rim of the bucket, making sure they never touch the ground). One winter I tipped out one of these buckets, and discovered that the thickened roots had almost all formed right at the bottom – making it easy to nip off the best ones to eat. I then put some compost in the bottom before putting the whole mass back in on top. They respond well to this treatment, and also become more willing to produce seeds, which I plan to use to start new pot-colonies.
It’s not really in the spirit of forest gardening, in which the plants are meant to be more integrated than this. It’s also a challenge with other shifting-sediment plants like asparagus, which rely on their environment to deal with competitors and are intolerant of any competition. However, I can picture an analogue of the lazy bed, with a well-edged raised bed, regularly topped up with the abundant compost produced by a forest garden. This wouldn’t have the bottom-of-the-bucket effect but would probably create a soil loose enough to be dug easily.
Incidentally, I haven’t been following my usual practice of giving Latin names alongside the English ones in this post. This is because the naming of silverweed is, frankly, a mess. It’s an aggregate species which can be divided into many or lumped into one according to taste and fashion, and systematists can’t even agree on which genus to place it in. It is (probably) called Potenialla anserina today, but the genus name Argentina is also commonly used.
Honey under ground
Silverweed of spring.
Honey and condiment
Whisked whey of summer.
Honey and fruitage
Carrot of autumn.
Honey and crunching
Nuts of winter
Between Feast of Andrew
Carmina Gadelica, from translation edited by CJ Moore, Floris Books 1992 p366. Thanks to Alison Tindale of the Backyard Larder for putting me on to this reference.