For some, it’s snowdrops; for others, wild garlic. For me, I know the corner to spring will have truly been turned with the first mouthful of homegrown rhubarb. That vivid pink of forced rhubarb seems to be pulled from winter’s snooze by the return of the dawn chorus and the lengthening days.
Rhubarb gives two very distinct harvests: the deliciously sour stalks of summer into early autumn and these paler vibrant-pink forced stems that cheer late winter into spring. I wouldn’t be without either. The latter is rightly expensive to buy – the process of lifting the dormant crowns, taking them indoors to dark warmth to be coaxed into tender, sweet productivity and harvested by candlelight is a specialised and costly business. However, it is one that’s easy to replicate in your own garden.
Ceramic forcers that exclude light and create a microclimate are widely available, but I’ve used a large plant pot and an upturned rubbish bin to great effect – the idea is to create a warm environment that fools the plant into thinking it’s late spring. The absence of light prevents photosynthesis. Instead, the plant uses its own starches to drive growth, resulting in the characteristic pale, vivid stems and that characteristic sweetness as the starches are converted to sugar. Manure heaped around the base of the forcer raises the temperature and speeds things along.
I force about a quarter of my rhubarb plants, in a four-year rotation to ensure they aren’t pressed into early service too frequently. Once I’ve picked the early forced stalks, I let them recover for the rest of the year.
Rhubarb will survive in most conditions, but give it full sun or partial shade in a moisture-retentive soil with good drainage and it will be highly productive, healthy and look its best. Plant them as crowns (the dormant core of the plant) or as potted plants, spacing them 32in apart, with the top of the crown just over an inch below the soil surface. Sit on your hands and allow them a year to establish before picking.
Choice of variety is crucial to both flavour and when you get to enjoy it. I like a long steady harvest, so I grow varieties that overlap in their peak productivity. First up is Timperley Early, a fabulous, reliable early producer from February, earlier still when forced. Prince Albert has a fine flavour, producing bright-red stalks early in the season. Following on is Stockbridge Arrow, a brilliant modern Yorkshire variety that produces masses of long, thick, deep-red stems over a very long season.
For summer, Victoria is the classic heritage variety that wakes late, then gives a long, steady harvest from May into August. I’ve also recently added Sid 51, a superb new variety that produces well into autumn.
How you harvest is crucial to the beauty and vigour of your plants. Pick by gripping the stem low, near the crown, and twisting as you pull – this separates the stalk without a cutting or snapping wound, which can cause the base to rot. Take only a third of what’s ready on each plant at any given time and stop as it slows in productivity. Remove and compost the green leaves from the stalks you harvest, as they’re high in oxalic acid and not to be eaten.
As well as the familiar rhubarb, I grow Himalayan rhubarb (Rheum australe). It’s quite the striking cousin, being wider, taller and with huge, thick stalks. Himalayan rhubarb’s flavour is superb – a little closer to cooking apples than familiar rhubarb, but I tend to pick little as I love its looks. By mid spring, it’s already established a mass of large leaves and is starting to send flower stalks skywards. These striking stems can reach 16ft or more in as little as a week.
Ordinarily, I’d advise you to remove the flower stems the moment you see them on a rhubarb – they take some of the plant’s energies and slow productivity – but these are too marvellous to miss.
The flowers remind me what a striking plant rhubarb is, as deserving of a place for its looks as for its harvest. To keep it at its best, water around (but not on) each crown through extended summer dry spells and mulch around the crown with compost in late winter – this will feed the plant, while helping it to retain moisture through the growing season.
Mark Diacono grows edibles, both usual and unusual, at Otter Farm in Devon (www.otterfarm.co.uk)
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