Though strictly speaking a vegetable, rhubarb is most often used in the manner of fruit, and in that category it is rather useful, providing the first fruit of the year long before the earliest of the summer soft fruit. Rhubarb is easy to grow with few problems. It appreciates a sunny spot with a rich soil for best results, but tolerates shady corners well and is not particularly fussy about conditions. It can be planted and all but forgotten for a few years, although the crown will, at some point, become crowded and benefit from splitting up, replanting the younger parts to replace the old and unproductive.
Rhubarb provides its best crop in spring and early summer, becoming rather coarse and acidic later in the season, although some varieties can provide reasonable stems throughout the year. Though stems can be cut from plants grown in the open, the very finest stems come from forcing the crop. Forcing is an old technique that is applied to various crops, such as asparagus and endive. It can be done to vegetables that, in the previous growing season, store a great deal of energy in their roots. They can then be brought into a warm, dark, place, where the new growth will shoot using the stored energy. Such growth, in the absence of light, will be pale in colour – referred to as blanching – but, more importantly, will tend to be more tender and sweet than that grown in full light. In the case of endive, the growth is less bitter, and in the case of rhubarb, it is markedly less acidic.
For rhubarb, it takes several years before the crowns are ready to force. In the traditional commercial process, the crowns would be grown in the fields for two or three years before being brought into large sheds heated with coal fires and lit with a few candles. In such an environment, the stems grow very quickly, but the crowns are exhausted at the end of the process and are discarded. One could, of course, replicate this process at home, but one can do so in the open ground without discarding the crowns which is arguably more convenient for the home garden or allotment.
In the kitchen gardens of old, clay forcing pots were placed over the crowns in late winter to exclude the light. Extra heat would often be provided by heaping fresh manure around the pots, which produces warmth during decomposition. In that way an earlier crop could be produced, which was much appreciated at a time when the garden would otherwise be rather unproductive.
Clay forcing pots can still be bought, but are rather pricey, however anything that effectively excludes the light can be used, such as a large pot or dustbin. The use of extra heat, whether from decomposing manure or some other means, is not essential either, the crop will just appear a little later in the season. Earlier this year, as the crowns just started to show signs of life, we covered two of them with a couple of spare water butts. Although not particularly early in the season, as those unforced crowns are also ready to harvest, they have just provided a wonderful crop of pale stems, from creamy white to pale pink, with a more delicate flavour and texture, and less acidity than those grown in the open.
Once the forced crop has been taken, the crowns are left uncovered to regrow. They should not be forced two years in a row, as the crowns may be overly weakened. For that reason we have three crowns of each variety that we grow. One crown can be forced each year, and from one a full normal harvest taken, whilst the previously forced crown is allowed to recover with perhaps just a few stems taken.
One can use rhubarb in all manner of dishes, but we have little of this forced crop and like to enjoy it on its own, simply poached in a light syrup until tender. Several flavours work well with rhubarb, vanilla and stem ginger – the sort sold in jars of syrup – being particularly fine. Both of these flavours work well together, so I like to add a little of each to the poaching syrup.