EFN EXCLUSIVE. Blauwe Groninger kale is one of our absolute favorite plants. It is a Brassica napus kale (a species derived from a natural hybrid of cabbage or standard kale — B. oleracea — and turnip — B. rapa — untold generations ago) along with the popular varieties 'Red Russian', 'Ragged Jack', and 'Siberian'. Blauwe Groninger means "Blue from Groningen," after the city in North Holland, and due to this provenance it is incredibly hardy. We call this strain 'Willem's Blauwe Groninger' after the great friend, Willem van Leeuwen, who originally provided it to EFN Co-Founder Nate Kleinman (and to differentiate it from the other strain in circulation in the United States). This population is primarily derived from a single plant that overwintered unprotected in Jenkintown, PA, about a decade ago. But despite this genetic bottleneck, this strain remains hardy and strong (most seed saving guides urge seed savers to have a population of at least 50 plants for healthy maintenance of Brassica varieties). We have been told that this is the case due to Brassica napus containing the chromosomes of both turnip and cabbage.
As far as we know, only one other Blauwe Groninger strain is available in the US — from Nichols Garden Nursery in Oregon — but theirs was descended from a strain that existed in Canada for decades before being passed to Nichols by our friend Dr. Carol Deppe, the legendary plant breeder and author. We had the chance to grow both Carol's strain and Willem's strain side-by-side and found much more variation in Carol's, so we presume that during its years in Canada the genes of other varieties got mixed up with it. Willem's Blauwe Groninger produces highly uniform, vigorous plants featuring large leaves with vivid purple spines and veins. The leaves are bigger and firmer than 'Ragged Jack,' but much more tender than most kales (even 'Tuscan Black'). It makes the best salad kale imaginable, but also stands up well to cooking. Even the rib is delicious (great for pickling!). The only downside is that it is a challenging market variety, since its bottoms need to be cut and put in water (like asparagus) to prevent wilting. But if you are a home gardener or restauranteur, it will doubtless become a staple. It has a delicious, mildly spicy, mustardy flavor quite unique to this variety. It also persists well into winter, producing edible leaves even after quite a few frosts (which makes them a more vivid purple), and usually survives whatever winter throws at it to produce more tasty greens in the early Spring and finally flowers and seeds. There are few plants more beautiful or delicious.