Rhubarb

Origin & history

Rhubarb comes from Siberia and Mongolia and is botanically a knotweed, a relative of sorrel and buckwheat — which is where the sourness comes from. What reached Europe first was not the stalk but the dried root: a commodity carried along the Silk Road that was at times dearer than cinnamon. Only around 1800 did the English start cooking the stalks, once sugar had become cheap enough for it; from there the use as a vegetable came to Germany in the 19th century, where rhubarb stood in every cottage garden for generations.

Varieties

Three grades, and they taste noticeably different: green-stalked types like “Goliath” crop heaviest and are also the sourest, red-skinned ones with green flesh such as “Victoria” sit in between, and through-coloured varieties like “Holsteiner Blut” or “Frambozen Rood” taste milder and turn a compote pink by themselves. For early forcing “Timperley Early” is the usual choice. Buy a potted division with at least two fat buds, or take a piece off a neighbour’s crown; plants raised from seed come out uneven and need a year longer.

Care

The buds have to end up just under the surface, with at most five centimetres of soil over them — set deeper, the whole rhizome rots in its first winter. Reckon on a square metre per plant and a bucket of well-rotted compost each autumn, and a crown will carry on for twenty years. Harvest nothing at all for two years after planting, however tempting the stalks already look. Break flower heads out at the base as soon as they show. For a fortnight’s head start, put an upturned pot over the crown in February; the forced stalks are tender and pale, but that crown then gets a year off.

What can go wrong

The commonest mistake is picking too early and too hard: strip a young crown and you get thin stalks for years afterwards. If an old plant turns them out thin and numerous of its own accord, the crown has aged out — every eight to ten years dig it up in autumn and split it with a spade into fist-sized pieces, each with one strong bud. A plant that runs to flower every year is usually short of water in May or standing in exhausted ground. Where water lies over the crown in winter the neck rots; a slightly raised planting mound settles that for good.

Harvest, storage & kitchen

Pick from mid-April to midsummer day on 24 June, never more than half the stalks at once — the leaves left behind keep the plant going. Cut the leaf off out at the bed and put it on the compost heap; only the stalk goes to the kitchen. Stalks pulled early are tender and milder than the coarse June ones, which want peeling. Wrapped in a damp cloth they keep a week in the fridge, and cut up raw they freeze well in portions. Do not cook rhubarb in bare iron or aluminium: the acid turns both pan and compote grey, and five minutes is plenty before it collapses to mush.

Frequently asked questions

When do you plant rhubarb?

Two slots work: March to mid-April, or early October to mid-November. Autumn is the better one, because the crown roots in before it shoots. A crown set out in spring needs noticeably more water through its first summer to make up for it.

Can I still harvest rhubarb after it has flowered?

Yes, the stalks stay usable and taste no different. Snap the flower stem out as low as you can as soon as it shows, or the stalks that follow come thin and stringy. The thick flower stem itself is too woody for the kitchen. Either way, picking stops on 24 June.

Is rhubarb winter hardy?

Yes, an established crown takes any winter. Everything above ground collapsing and vanishing in autumn is part of the cycle — the new shoots push out of the rhizome in spring. If young April leaves catch a night frost they go slimy, but the crown simply sends up fresh ones.

Can rhubarb be grown in a tub?

Possible, but a compromise: in the ground a crown claims a whole square metre, and in anything under 40 to 50 litres it stays stunted. If you try anyway, water almost daily in summer and move it into fresh compost every three years.