Perennial kale breeding

I notice it’s been five years since my last post on perennial kale breeding. Enough time for some progress surely? Happily, yes, and I now have an abundance of seed to share with anyone who wants to join in. I’ve been aiming to produce a range of kales that are mid way between the near-sterile Daubenton’s perennial kale and the traditional biennial kale: that is to say, plants that flower enough to breed from but don’t flower themselves to death. I have been increasing the diversity by crossing all my favourite traditional kales with plants that have these traits.

Not all of the results are finished varieties that I’d want to propagate vegetatively, but all have at least one trait I want to keep in the population. Some of my favourites haven’t flowered yet: these are the ones that I have been able to collect seed from this year. The hands in the pictures are for scale and measure 22 cm. Seeds of all these and a few more are available on my seed list. Please note that they are all open pollinated, so seedlings will show considerable variation – which is part of the fun!

Purple kale tree

This is perhaps my favourite that I have seed for. It is seven years old and still growing strong: the original stem grew to about 10 cm and eventually died, but others have taken its place and it roots itself by layering, Daubenton-style. The leaves are large, tender when young and, of course, purple. Flowering intensity: low. Flowers: white. Some of PKT’s offspring are similar but with even larger leaves and faster growth.

Here is one offspring of PKT that hasn’t flowered yet.

And one that has, imaginatively titled ‘Son of PKT’. It has the same tall growth habit but a leaf shape that might indicate a cross with ‘Cabbagey’ (see below).

Flowering Daubenton’s

This is the most similar to classic Daubenton’s with similar leaves and growth habit, but it flowers every year, with a medium flowering intensity. Not a great kale in itself, but good for breeding off, especially for its strong branching habit and short annual growth which give it a relatively neat, dome-like form.

Deep purple

With deep purple, lobed leaves and a rather straggly growth habit. Hand for scale.

Oak leaf bush

Large, lobed green leaves and a bushy habit. Flowering intensity: high.

Lobed purple

Another of the lobed-leaf group, this time looking like it has Ragged Jack in its ancestry. Strongly branching. Flowering intensity: low.

Cabbagey

Not in fact a single variety, but one original plant and its nearby offspring, all of which I suspect have a cabbage somewhere in their offspring, giving unexciting but mild leaves. With a very straggly growth habit and moderately high flowering intensity.

Tall savoy

Tall, upright ‘kale tree’ growth habit, with somewhat savoyed leaves. Medium flowering intensity.

Big leaf Jack

The flattened winged stems of this variety remind me of Ragged Jack and it has big leaves. Flowering intensity medium-high.

Big green lazy

Not an awful lot to recommend this one, apart from its large leaves. It’s quite susceptible to mildew at this time of year, although the younger leaves that I pick are unaffected. Long, floppy stems that mean that it forms a thicket. Medium flowering intensity.

Nero di Toscana perenne

Three plants arising from a cross between Purple Kale Tree and Nero di Toscana. Need back-crossed a few times to form a true perennial Black Tuscan Kale. All three are very tall, reaching over 2 m in 2 years (too tall in fact – need to breed in shorter internodes). The first flowered strongly this year and, for obvious reasons, this is the one I have seed for. The second flowered very lightly, which would be perfect but unfortunately I only managed to collect a tiny amount of seed. The third (the most NdT-like) has not flowered at all. I have had to give up the site where these were planted but I have taken lots of cuttings, so fingers crossed.

Plant 1
Plant 2
Plant 3
Leaves of 1, 2 and 3 (L to R)

Daubenton’s kale – growing and cooking

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 [but see The Joy of Promiscuity], 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. At most times of year you can plant cuttings or put them in water and the roots will start to grow. In autumn, Daubenton’s undergoes a brief hiatus when it slows its growth and sheds a lot (but by no means all) of its leaves. I’ve noticed that at this point its capacity to grow from cuttings is much reduced, so if you have failed to get them to root at this time of year, don’t give up. Another method is to layer branches by bending them down and burying a section. Over time the buried section will develop roots and make a new plant.

I got my first Daubentons in 2009 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 and Pennard Plants have both kinds. Cotswold Garden Flowers sell the variegated form (plants simply disappear from their list if they are sold out, so if it’s not there, that’s what happened). 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. If you are in the States, you might like to look at the ‘Kosmic Kale’ supplied by the Territorial Seed Company. This claims to be a new variety but it certainly walks and quacks like variegated Daubenton’s.

My original plants have now all died out but they have given rise to several generations of successors. A mature plant typically makes a dome about one metre high and wide and lasts for about 5 years. Winter hardiness seems to reduce with age and I usually lose some older plants over winter, but taking cuttings or allowing plants to self-layer seems to reset the clock. The worst cold my plants have had to face was -15°C one year, which they did with aplomb.

I have planted cuttings 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. They are also ideal for kale chips (i.e. crisps).

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. It’s also sometimes seen as ‘Dorbenton’, which seems to be an English phonetic spelling.