After a short Christmas break we are now ready to write our book on perennial vegetables. As part of the work on the book, I started a few months ago to immerse myself in the multiannual kålplantornas world and have found a lot of interesting that I would like to share with your readers.
All the familiar cabbage varieties we grow today - as cabbage, brussels sprouts, broccoli and cauliflower - is different varieties, Thus, "local populations"  an even Species, Brassica oleracea. All these are grown as annuals vegetables, but there are also perennial types of cabbage. They are among the more difficult to grow perennial vegetables and it has been difficult to find information about their hardiness in the Swedish climate. Furthermore, the data on these plants in the literature some conflicting, but I have tried to sort things out.
In England and France, it is common to find a perennial cabbage called "Daubenton". It belongs to the variety Brassica oleracea var. branched, which means "cabbage with many branches". It is normally grönbladig, but there is also a brokbladig variant that should be slightly less hardy than green leafy . Sometimes bloom Daubenton and then produce viable seeds, otherwise multiply it with the help of cuttings. As the name implies, har kålsorterna i varieteten branched a sprawling growth habit and a full-grown plant takes up an area of at least one square meter . The perennial bowl used like kale, from early spring onwards, until it is torn by all sorts of vermin in high summer.
In many German nurseries will find the so-called "ewiger Kohl" which also belongs to the variety branched. Ewiger Kohl is nothing more than a somewhat poetic name for perennial cabbage and unfortunately this seems to have led to the misconception in the literature that ewiger Kohl is a varietal names [4, 5]. Depending on who you buy from, you can get a little anything that is sold under the name ewiger Kohl, for there are at least 20 or so extant name resorts on Brassica oleracea var. branched . Even the kind Daubenton marketed in Germany under the name ewiger Kohl, which makes it even more confusing.
”Helgoländer Wildkohl” (Brassica oleracea ssp. oleracea) grows wild in the small German island of Helgoland and has a bit more tall plant than Daubenton, but is in bloom the second or third year and can be easily pulled up from seed. This perennial cabbage is the only one of those mentioned here, we have our own experience, and it has thrived for three winters with us. We use the leaves from snowmelt and until about midsummer. They are tender and bland in flavor and can be raw or cooked as kale.
Another kålvariant is kind "Nine Star Perennial" (Brassica oleracea var. botrytis) mentioned a lot in the literature. It is a kind of perennial broccoli produces numerous small flower buds used in the same way as regular broccoli. It is a little hesitant as perennial vegetable when the flower buds must be reaped all the time, otherwise the plant is in bloom, and then it dies usually shortly thereafter. According to information we have received has fared well with no further supervision in Uppland plains outside Enkoping , but it is no longer the experience of this plant in our climate.
There is even a sort of tree-like kålväxt called Tree Collard in English (Brassica oleracea var. acephala) and mentioned that several years in the English literature. In Sweden, it is probably no point even trying, when its frosthärdighet is close to zero, but it is possible to grow it as an annual plant and seed sold under the name trädkål.
Some general tips for these types of brassicas is that they need to be very well-drained soil. In addition, several of them we had contact with the reported cabbage plants do best in partial shade, when they appear to have hard spring sunshine. Here is, deer and voles very fond of cabbage so it may be worth investing in a protection against these pests. Otherwise, it can easily happen that the plants are weakened so that they do not survive the winter. The first year's seedlings addition, much loved by slugs, from the second year of time, however, they usually get started long before the snails. Fastness wise think most people we've talked to that they are difficult to grow outside the cultivation zone II, which would correspond retardant class D. Moreover, it seems that according to two independent sources that perennial cabbage and deep snow is not a good combination [3, 8], which of course is bad news for those who grow in the snowy parts of the country where snow usually creates good conditions for growing perennials. The alternative is to produce snow shovel.
Shortly said: There is much left to explore among the multiannual kålsorterna and I am grateful for you readers want to share with us any personal experience with these brassicas. And if someone has nice pictures on them, we gratefully accept them to book!
 SLU. SHOT, Swedish Culture Plant Database. Accessed 2015; Available from: http://www.slu.se/skud/, 2015.
 Blomquist, B., 2015.
 king, W. Perpetual carbon (Brassica oleracea L. our. ramosa DC.). Accessed 2015-12-05; Available from: http://www.wiesenfelden.de/ogv-zinzenzell/pflanzenportraits/ewigerkohl.htm, 2009.
 Barstow, S., Around the World in 80 Plants An Edible Perennial Vegetable Adventure for Temperate Climates. Permanent Publications, 2014.
 Nilsson, I., Cabbage. The publishing Arena, 2015.
 Seven, A.C., K.J. Dehmer, T. Gladis, K. Hammer, and H. Lux, Are the duplicates of perennial kale (Brassica oleracea L. our. ramosa DC.) true duplicates as determined by RAPD analysis? Genetic Resources and Crop Evolution, 45(2): p. 105-111, 1998.
 Franzen, O., 2015.
 Toensmeier, E., Perennial vegetables : from artichoke to zuiki taro, a gardener’s guide to over 100 delicious, easy-to-grow edibles. White River Junction, Vt.: Chelsea Green Pub., 2007.