Some time ago, I wrote a post about the principles of perennial kale breeding. Since then, I’ve been aiming to produce a population 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.

Here is a round up of where I am at. 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. The ones at the top are still alive and you’ll find seeds on my seed list. Please note that they are all open pollinated, so seedlings will show considerable variation – which is part of the fun! Towards the bottom you’ll find information on cultivars or grexes that I no longer grow but that I have sent out seeds of in the past.

The hands in some of the pictures are for scale and measure 22 cm.

Last edited May 2025.

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

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.

Cabbagey

I suspect that this plant had Brussels sprout somewhere in its ancestry, giving unexciting but mild, cabbagey leaves. With a very straggly growth habit and moderately high flowering intensity. I still have some seed of this but not the original plant. Its influence is visible in the cultivar that I call Silver Kale Tree, but most of its offspring have been a bit too much on the straggly side.

Silver Kale Tree

A very interesting plant, looking intermediate between Cabbagey and Purple Kale Tree. The leaves are nothing spectacular, but it has a very heavy crop of sprouts in spring – despite which it has come back year on year since 2021. It is the first plant in which I noticed a ‘coppicing’ habit, – growing new shoots from the base rather than just going up and up. Sometimes these side shoots collapse, but the plant as a whole keeps coming back. As a result it is more bushy than tree like, but I named it from its similarity to PKT.

Nero di Toscana perenne

A group of plants (originally three) arising from a cross between Purple Kale Tree and Nero di Toscana. . They are generally very tall, reaching over 2 m in 2 years (too tall in fact – need to breed in shorter internodes).. I have had to give up the site where these were originally planted but I took lots of cuttings and have fortunately managed to preserve all the lines I had on the old site. The flavour is generally recognisably Tuscany-y.

It has been hard to find the balance between flowering and perenniality in this group. The best plants are completely perennial, leaving me to try to breed from the inferior but more heavily flowering ones. I am trying to back-cross them with biennial Nero and they are also of course crossing with my other perennials. Obviously the seed I have to offer is from the more heavily flowering ones.

Perennial Brig

Pentland Brig is one of my favourite kales for flavour and texture. It is a heritage variety resulting from a cross between Thousand Headed kale and curly green kale. It has been self seeding in my allotment alongside my perennials for many generations (of kales) and now some of the individuals are at least short-lived perennials themselves, while remaining recognisably Briggy.

Variegated perennial kale

The variegated trait has been knocking around in my population from the start and I have tried to encourage it. As a result it is becoming more common and I have a few perennial plants with variegation, although only the cold-season type that disappears in summer. One is a yellow-and-green-leaved plant that seems to be non-seeding (but I have seed from a heavy-seeding sibling). Another is a more complex white, green and purple mix (a suffragette kale?) that is showing something of the multi-stemmed ‘coppice’ habit of silver kale tree.

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2021 update

The winter of 2020/21 was a cold one in Aberdeen, with temperatures down to -15 degrees C: testing temperatures for a kale. This was great for plant breeding, in that it weeded out the less cold-tolerant varieties, but less good for individual lines.

A majority didn’t make it. My oldest plant of ‘Purple Kale Tree’ died, but another grown more recently from a cutting sailed through. This is often the case with perennial kales. Unfortunately the survivor plant barely flowered this year so I can’t offer seed for a while. The oldest individual plant to survive was ‘Flowering Daubenton’, adding to its list of impressive qualities. The Nero di Toscana crosses also did well, although this might owe more to them all having had to be regenerated from cuttings last year than inherent hardiness. Plant 2 didn’t flower at all, but 1 and 3 did so I have seed from this line for others to experiment with. This year’s to-do list includes sowing some actual NdT in the same bed to do some back-crosses. One purple-ribbed plant both made it through the winter and seeded. It wasn’t one of the ones that seeded last year, so it doesn’t have a name yet. Come to think of it, I might call it Purple Rib.

Another plant, with greener leaves, both came through the winter and is showing impressive mildew resistance at a time of year when many plants get badly affected – but unfortunately showed no inclination at all to flower. Some others which sprouted last year and survived the winter had the opposite problem: they flowered too much to be considered good perennials and were removed from the gene pool. I also decided to get tough with a tendency to straggliness in one group and removed all plants that were too floppy.

You can’t keep a good perennial kale down though, and everywhere where one has died several more have sprung up over the course of the year. I have thinned these to leave the more interesting and sturdy ones and now have nothing to do but wait to see how perennial they are. For interest, some of the lost plants are described below.

2022 update

A better year for kales, with no losses over winter and a few interesting new plants passing the tests of flowering and growing back. I have also acquired a range of perennial kales, such as Taunton Deane, that I didn’t have before and can now add to the gene pool.

2025 update

For reasons of space I’ve had to concentrate on a few of the most promising lines. My favourite, but also currently the most frustrating, is the perennial Nero di Toscana. A successful cross between my most reliably perennial clone (which I christened Purple Kale Tree) and annual Nero di Toscana gave several similar plants with leaves similar to its Italian parent but a much taller growing habit. Unfortunately if anything this has been too successful a perennialisation. After a few years of producing seeds the original clones have now renounced the habit and become fully asexual perennials. I had hoped to back-cross them with annual NdT, but I am now having to do this with their offspring instead. Watch this space.

Another attempt to perennialise an existing kale is going better. Pentland Brig is a favourite of mine and it has been self seeding in the allotment for years, interbreeding with the perennials in the process. I’ve selected fairly hard for staying true to type, which rather selects against perennial genes, but nonetheless my plants have been becoming slowly more long-lived and are starting to reach the balance between flowering and growth that I look for while staying recognisably Brig-ish. Finally there are the variegated kales. I can’t resist selecting for this trait and again it’s slowly becoming more widespread. Of course selection for a purely visual trait reduces the ability to select for anything else, so these aren’t my best kales, but I’d like to keep it in the population so that it can cross with the more culinary ones. 

The perennial kales that I planted from cuttings in 2022 have generally been a disappointment and a reminder of why I moved away from traditional perennial kales. Taunton Deane in particular turns out to be a sprawling thug. I know some people with more space who like it, but for my allotments habit of spreading by growing tall, collapsing and rooting made it quite a handful, especially in exchange for rather mediocre leaves and no spring shoots. It was completely non-flowering and (perhaps thankfully) offered no opportunities to breed from it. The only one that shows some promise in terms of both flowering and surviving is one called Thousand Headed Kale.

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Plants from here on are no longer on my seed list.

Deep purple

With deep purple, lobed leaves and a rather straggly growth habit. This straggly habit was also pronounced in its offspring and I ended up discontinuing the line.

Big leaf Jack

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

Tall savoy

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

Lobed purple

Another of the lobed-leaf group, this time looking like it has Ragged Jack in its ancestry. Strongly branching. Flowering intensity: low. The parent plant died in 2023 but its genes live on in the gene pool.

Big Green Lazy

I ended up evicting this plant from the gene pool. It had big leaves, but the ‘lazy’ in its name refers to its habit of growing very thick, sprawling stems which made it a hard plant to manage. I am now selecting for more compact, upright plants.

Oak leaf bush

Large, lobed green leaves and a bushy habit. Flowering intensity: high. Died in the cold winter of 2021.

Variegated Kalettes

I got quite excited about this one. It appeared to be a cross between Brussels sprout (my allotment neighbour let his flower a couple of years ago) and kale – a combination now being marketed at ‘kalette’. It looked quite ordinary until cold weather set in, when it started to become variegated, a feature that persists into the sprouts. Moderate-to-high flowering intensity but regrew strongly. Unfortunately it didn´t prove to be very long-lived, but the cold-season variegation remains in some other plants.

Purple Rib

Grew in 2020 and survived 3 flowerings, despite flowering intensity being much higher than ideal for a perennial kale. Attractive, tasty leaves. Form rather too sprawling and I eventually removed it for this reason.