Daubenton’s kale (Brassica oleracea var ramosa) is a perennial vegetable that seems to have everything going for it: tasty, hardy, productive and easy to grow.
I also grow nine-star perennial broccoli (Brassica oleracea botrytis aparagoides – actually a sprouting cauliflower) which is often touted as a perennial, but really it’s just a biennial that manages to hang on for a few more years if you zealously remove all the flowers. Daubenton’s, on the other hand, is the real deal, a perennial kale that usually lives for 5 or 6 years.
It seems that a lot more kales used to be perennial, but Victorian seed companies selected for biennialism in order to be able to sell the same variety year on year. A few old varieties have hung on by being passed from gardener to gardener, leading to a plethora of names such as Ragged Jack, tree collards, Woburn kale, Taunton Deane and many others which may or may not be the same as each other. Worse, some biennial varieties share a name with perennial ones having been bred from them. My all-time-favourite biennial kale is Pentland Brig; there’s a rumour of a perennial version out there which I dearly hope is true. In Germany there’s an ehwiger kohl (‘everlasting kale’ or, as Google Translate charmingly puts it, ‘eternal carbon’).
The bargain that Daubenton’s makes for its long life is that it is lived in complete celibacy. It is hardly ever known to flower, which means that it doesn’t exhaust itself, but adds a problem for the gardener: no flowers means no seeds, perhaps giving one reason why it is so rare. Fortunately, it is extremely easy to propagate from stem cuttings, particularly if you break off branches near the base. You’ll find some knobbles which are incipient roots: plant them or put them in water at almost any time of year and they will start to grow.
I got my Daubentons three years ago from Pépinière Eric Deloulay in France. He’ll deliver to the UK but there doesn’t seem to be an English version of the website, so you’ll have to scrape your secondary-school French back together or Google Translate it and run the risk of buying some eternal carbon by mistake. I got two versions, one green one with a red tinge to the leaves and another, variegated, one with larger leaves. The Agroforestry Research Trust now sell the non-variegated variety too. I’m often asked about suppliers in the US and Australia. I haven’t managed to track any down, but if you’re a supplier, or know of one, anywhere outside Europe, let me know and I would be happy to put up a link.
My original plants have grown vigorously and are now both domes about one metre high and wide. I took several cuttings in the first year and some of the daughter plants are almost as large, despite me eating from them on a regular basis. They have survived one winter down to -15°C. This is about as cold as they are meant to be able to tolerate, so this year I kept some cuttings in the fridge during the coldest months so that I could restock in case of disaster.
I have planted them in various positions in sun and part shade (under an apple tree) and they have thrived in all of them. This ability to tolerate shade makes them ideal for my forest garden set up. They are also said to be very tolerant of soil conditions.
I use Daubenton’s pretty much wherever I would use an annual kale, in soups, stews and stir-fries. In summer I mostly use it as a pot-herb, usually in a 50-50 mixture with sea beet. The kale takes longer to become tender than the beet, so you have to make sure it is cooked enough. In winter the leaves become sweeter and tenderer, enough that I start to use them in salads too.
Incidentally, Daubenton’s kale was named after the great French naturalist Jean-Louis-Marie Daubenton, a man who has had to suffer the posthumous indignity of English speakers constantly sticking an apostrophe into his name in order to make it look more French, so you’ll often find the plant referred to as D’Aubenton’s kale or even chou D’Aubenton.
NOTE. I am sometimes able to supply Daubenton’s plants as cuttings, but I only have a few plants so I run out quite quickly. I won’t have any more until next year.