The Intro - useful for seed savers*
Let's start with the basics. Brassicacea is a large family including ornamentals such as sweet Iberis, and honesty plant (lunaria) and weeds such as hedge mustard and pepper grass. It also includes many common garden vegetables such as broccoli, and turnips.
The brassica genus -
interjection: The cross-language snob talk plant is like this 'Genus species'
- seems to highly represented in the safe and tasty category of plants across many different species. Plants that are in the species can cross pollinate one another creating weird (and sometimes wonderful) hybrids. However, the general rule is that those are different species, even though they have the same genus, will not cross (rules were made to be broken ;-).
These veggies fall under the following Genus species names - by no means a complete list:
Brassica oleracea: cabbage, cauliflower, broccoli, 9 star broccoli, sprouting broccoli, chinese kale, broccolini, white flowering broccoli, marrow stem kale, jersey kale, walking stick kale, palm leafed kale, perpetual kale, curly kale, brussel sprouts, European kale, collards, kholrabi and wild cabbage.
I am sparing you the variety name as they are quite complicated but, for examle, brassica oleracea var. botrytis is cauliflower versus Brassica oleracea var. albogladbra for white flowering broccoli. As these are all members of the same genus and species, they can all cross with each other. For more information, go to Sorting Brassica oleracea names.
Brassica napus include Siberian kale, hanover salad, rutabaga, rape and canola.
Brassica rapa (synonym campestris) include turnip, seven top, italian kale, mustard greens (some forms are in Brassica juncea), rapini (some forms are in brassica oleracea), broccoli rabe, chinese cabbages, bok choy types, tat soi type greens, holland greens, and mizuna.
Brassica juncea: Indian mustard greens
Presumedly as mustards in the Brassica juncea and Brassica rapa are different species, they will not generally cross with one another so you could save one of each type in your garden assuming that both can flower at the same time and yet still come true from seed.
Other edible Brassicacea include:
Eruca sativa: rocket / arugula - sylvetta can be perennial
Barbarea verna: land cress
Raphanus sativus: common radish
Armoracia rusticana: horseradish - perennial
Crambe maritima: sea kale - perennial
Possible perennial brassicas
9 Star Perennial Broccoli
I have never grown any so called perennial brassicas but I have heard of them. Representing the edible flower head form of brassica, commonly known as broccoli/cauliflower is 9 Star Broccoli. I understand that it is only perennial as long as you prevent it from going to seed. In plant terms this is sometimes known as monocarpic. Even then, I hear that it only lives for about 2-3 years. It has loose, white heads which look to me like cauliflower. I don't know if it could overwinter in Ottawa but heck if my mother living in Paradise... I mean, BC gets some seeds, I'm going to give it a try.
Source: Seeds of Victoria, Thompson-Morgan
For blanched shoots, you can try Crambe Martima or Sea Kale. It is a true, long lived perennial with white, wavy silvery leaves and typical sprays of brassica flowers after 4 years or so. It is mentioned in an old time book on Ottawa Gardening so I know that at least one variety is hardy around here.
Source: 'Lily White': La Societe des plantes, Bountiful Gardens
A perennial leaf verison of brassicas was by far the hardest to track down. I got my first lead at the Plants for a Future website, which uses the latin Brassica oleracea ramosa (or branched kale?) that details useful perennial plants. They listed three cultivars Ragged Jack, Thousand Headed Kale and Daubenton. The first is a bit mysterious because it is a synonym for Red Russian Kale which as far as I know is generally a biennial unless this is some other purple, wavey leafed cultivar of perennial kale rather than the usual 'ragged jack'.
Thousand Headed Kale is, according to one supplier, a fodder kale. My search has lead me to believe that it is a) not that winter hardy or b) in mild areas can live for years? One growing source called it 'hunger gap kale' which is promising and it seems to be grown for its flowering shoots produced early in the year hence the 'thousand headed' name. Pentland Brig is a plant produced by crossing Thousand Headed Kale but I have no idea of its perennial status, however, this website, suggests that it shows promise.
Source: B&T seeds, The Organic Gardening Catalogue (pentland brig), Country Plan, Bountiful Gardens (penland brig)
Lastly, I tried hunting down the most infamous of these three: Daubenton Kale. It is oft' quoted that it can be propogated by cuttings and I gather that it roots where it touches the ground? At any rate, putting Daubenton Kale in a search engine yields primarily results about trying to hunt down this cultivar... not very helpful until I ran across a mention of its French name. Chou d'Aubenton or simply Chou Daubenton. So I figured I'd use mediocre french skills for second time this month (read my recent discovery of La Societe des Plantes) and do a biligue search et voila! I found a source!! It sold seed for two varieties!! The first is simply named Chou Daubenton and says that indeed it is vivace (perennial) with the latin name Brassica oleracea and the second is Chou Daubenton panache or Brassica oleracea varigata. However, it does not seem like they ship them to Canada. Sigh.
Source: Plantes aromatiques (may only ship in Europe)
This is another leaf vegetable version of the brassica known most commonly as walking stick kale or brassica oleracea palmifolia (though some claim this is not the same plant but that tree collards refers to brassica oleracea ramosa or even Brassica oleracea viridis, another kind of fodder kale) because it grows to a very tall height with a tuft of leaves at the top. The stem is dried to harden into a strong, light weight walking stick. I am not sure if this is a true perennial or simply that it can live on more than 2 years if it doesn't flower. In other words, I'm not sure if it is monocarpic like 9 star broccoli. It does look very impresive in flower though.
Source: Thompson & Morgan
How brassicas behave / flowering
My experience with brassicas is that if you cut off the flowering head (cabbage head, broccoli or rapini spears) then the plant will reform new heads. In cabbages this takes a bit longer but eventually you'll get several smaller cabbage heads reforming where the original was cut. If flowering does not happen then the plant, at least in my garden, has a good chance of making it to the next year assuming the root system survives and with reliable snow cover this often happens. I've had curly kale, and red rock mammoth live for more than 2 years in my garden. Anyhow my suspicion is that brassicas can be kept 'young' by preventing the barring of young at least for awhile.
* Seed Savers: You may be wondering how many brassicas you need of each variety to save seed. Well, that answer depends on what plant you are trying to save and who you talk to. I have heard as few as 6 plants quoted but generally for the highly bred brassicas (read cabbage, broccoli, cauliflower, and brussel sprouts), it's more in the range of 50-200 (to quote off the top of my head - my copy of Seed to Seed has gone walkabout at the moment). As for the wilder cousins (like kale), I've heard as low as 20 to maintain vigour. Of course, in order to save seed from a brassica that flowers only in its second (or later) year, the plants will either have to overwinter or be stored and replanted.
** This will be an updated post as information on, or seed sources of perennial of long lived brassicas become available. If you grow any of the above varieties and have a blog post on them, I'd really love to include a link!