Last spring, 16 April according to my notes, my dad and I planted ten tubers of Jerusalem artichoke Violet de Rennes in the perennial bed, alongside the horseradish and rhubarb. The bed had been well dug, weeds removed as best we could, and the soil improved with horse manure and composted green waste. I cannot recall whether we also added a little fish, blood, and bone, but it is quite possible. After this preparation, nothing more was done. We left them to their own devices. We did not even water them through the dry periods. They grew to a height of eight feet or more, developing hefty stems and healthy foliage, but they did not flower as we were anticipating.
As we have been too busy with house renovations, we failed to cut down the top growth after it had died back, and their decaying stems are lying strewn across the bed wherever the winter winds took them. Suspecting they might be a bit of a wash out, this week we dug up two of the ten plants and were astonished with the results. We lost a few to careless fork work, not really expecting them to have spread quite so far as they had, but we still lifted over 6.5kg of what are, in my admittedly not extensive experience of this vegetable, very large tubers of superb quality: entirely firm, with clean, almost white, flesh under an attractive purple skin. In The Vegetable and Herb Expert, Hessayon notes a yield of 3 to 5lbs per plant, approximately 1.4 to 2.3kg, so these do seem to have performed very well indeed.
Jerusalem artichokes are something of an oddity. Although one can find them in the supermarkets from time to time, they are often not such great specimens, and do not seem to be either widely grown or widely consumed. That is a pity, because they appear to be a most excellent winter vegetable, heavy yielding, and standing well through the bad weather, just waiting to be dug when needed. Indeed, they should not be lifted much before use as they store best in the ground. They are, perhaps, something of an acquired taste, but their nutty flavour and crisp, succulent texture, somewhat reminiscent, to my mind, of water chestnuts, makes them an interesting and welcome addition to the winter food stocks.
Jerusalem artichokes are native to North America and, despite the name, have no obvious connection with Jerusalem, nor are they closely related to globe artichokes, which are cultivated varieties of cardoon, an edible form of thistle. Various possible explanations for the name have been posited, my favourite being a corruption of the Italian for sunflower, girasole, to which the Jerusalem artichoke is closely related. Both are of the genus Helianthus, the Jerusalem artichoke being Helianthus tuberosus, and signalling its close relation with sunflower like top growth and, in some sorts at least, simple sunflower like flowers. Whether Violet de Rennes will flower, given whatever favourable conditions may be necessary, I do not know. It certainly did not flower this year, despite reaching a great height and producing a great crop. That they became known as artichokes seems to be due to an observed similarity in taste with the globe artichoke, although I cannot see it myself, as I dislike these but rather enjoy the flavour and texture of Jerusalem artichokes.
Jerusalem artichokes have been cultivated in Europe for hundreds of years, but there is not, perhaps, the diversity in cultivars that one might imagine. The most common, at least in the UK, appears to be Fuseau, which is the only variety I have seen in garden centres and the catalogues of the mainstream seed merchants. The tubers of Jerusalem artichokes tend to be rather knobbly and bothersome to peel, but Fuseau is supposed to yield less knobbly tubers with smoother, easier to peel, skin. I am, though, a little contrary when it comes to varieties, so looked for something different. I found Violet de Rennes, an old purple skinned variety from Brittany, offered by Seeds of Italy, www.seedsofitaly.com, one of my favourite seed merchants. I ordered these along with some asparagus crowns. The crowns were superb, of great size, vigorous and healthy, and not one failed to develop. Similarly, the artichoke tubers were very good, although nothing like the size that they went on to produce, but each was sound and developed robust, healthy, and resilient plants. Whilst some of the largest tubers were knobbly, due to their size they were not difficult to prepare, and a great many were not knobbly at all, even though Seeds of Italy describe the variety as “knobbly but productive”. There is no doubt, though, concerning productivity.
Most important, of course, is flavour. Whether one likes the flavour and texture of the Jerusalem artichoke is a matter of taste, but for those that do appreciate them, this variety, to my mind, produces tubers of an excellent flavour. The tuber quality was also superb; every one that I prepared was perfectly sound, with the expected firm, crisp, texture. They tasted very pleasant raw, with the slightly sweet and nutty taste that one would expect. For their first outing, though, I sliced them, then pan fried in olive oil, added a good knob of butter and some seasoning, and finished them in a hot oven. These went down very well indeed, and were no doubt the best Jerusalem artichokes that I have tasted. I must admit, though, that I do not have so much experience with this vegetable – the first time I prepared them was a few years ago, after finding some in a veg box. I have since found them from time to time in the supermarkets. In all cases, the tubers were of a white skinned sort, were much smaller, perhaps a little more knobbly than many of those we have produced, and more fiddly to prepare due to their size. The flavour was consistently good, though. To my taste, however, Violet de Rennes has the edge on flavour. One thing to note in their preparation is that if peeled and left exposed to the air, the tubers will quite quickly discolour. Ideally, they should be peeled and placed immediately in a bowl of acidulated water, then sliced or diced as needed just before cooking.
Jerusalem artichokes can be quite an invasive crop, as they will regrow from any small tubers left in the ground. They are not, as far as I am aware, particularly bothered by pests and diseases, though, so can be cultivated in the same place for some years. I will reserve some suitable tubers for replanting, and will plant at a slightly higher density, perhaps 4 rows of 4 tubers, but not too close together so as to affect the size of the tubers. I will no doubt add a dressing of manure and probably a little fish, blood, and bone. Hopefully, Violet de Rennes will turn out to be consistent in its performance, in which case I will be able to recommend it wholeheartedly.