Growing and cooking rhubarb

A rhubarb plant can go on cropping in the same corner of a garden for years. Its pink and red stalks are the part people cook, and its big leaves stay out of the kitchen.

Where it grows best

The Royal Horticultural Society (RHS) calls rhubarb a perennial that lives for many years and copes with even the coldest sites. It needs room, because a clump can spread 1.5m (5ft) wide or more.

The RHS says rhubarb grows best in an open, sunny spot, in fertile soil that holds moisture without getting waterlogged. It will cope with light shade. On heavy clay or poorly drained ground, it suggests a raised bed or a large container.

Late frosts can damage the young stems, so the RHS suggests avoiding a site prone to them.

Planting

Rhubarb is more often bought as a young plant than grown from seed. Bare-root plants, called crowns, are usually on sale from November to March and are best planted soon after they arrive. Plants in pots can go in at any time, though spring and autumn are best.

The RHS suggests digging in two bucketfuls of well-rotted organic matter per square metre first. Set the crown so its tip sits just above the soil, firm it in and water it well. Plants go 75 to 90cm (30 to 35in) apart.

In a pot, the RHS suggests one at least 50cm (20in) deep and wide, with plenty of drainage holes.

Looking after it

Once a plant is established, the RHS says it rarely needs watering, except in long dry spells. A new plant needs regular water through its first growing season, and so does rhubarb in a pot.

Each spring, spread a mulch of well-rotted compost about 7cm (2.5in) deep around the plant. Keep it off the crown itself, which can rot if buried.

Flower stems should come off at the base as soon as they appear, so they do not weaken the plant. The RHS suggests dividing a large clump every five years or so, while it is dormant.

Picking the stalks

It takes some patience at first. The RHS advises picking no stalks in the first year after planting, and only a few in the second. From the third year a plant can be picked normally.

Most varieties are ready from April or May. The RHS suggests stopping in late June or early July, or taking only a few stalks after that, so the plant is not weakened.

Choose a young stalk about 30cm (1ft) long. Hold it at the base and twist it gently out of the ground. The RHS says not to cut it, because the stump left behind tends to rot. Take no more than about a third of the stalks at a time.

The leaves are not for eating

The RHS says the leaf is not edible and should come off as soon as the stalk is picked. It names the poison in the leaves as oxalic acid.

The leaves can still go on the compost heap. The RHS explains that the oxalic acid breaks down as they rot.

Some people worry that oxalic acid builds up in the stalks as the season goes on. The RHS says the build-up is mostly in the leaves, and the amount in the stems is too small to have a toxic effect.

Forcing an early crop

Gardeners can force rhubarb for an earlier, paler and sweeter crop. In mid-winter, the RHS suggests covering a strong, healthy plant with a forcing jar, a tall bucket or a dustbin, so the stems grow in the dark. An early variety suits this best.

Forced stalks are picked at about 30cm (1ft), which can take four to eight weeks after covering. Then the cover comes off, and that plant is left unpicked until the following year. The RHS advises against forcing the same plant two years running.

Yorkshire Forced Rhubarb has protected status in the UK. Defra lists it as a Protected Designation of Origin (PDO), registered in the UK scheme on 31 December 2020.

In the kitchen

Rhubarb is a vegetable, but the RHS notes that it is traditionally eaten as a dessert, baked in pies and crumbles. It also goes into chutneys and savoury sauces.

The RHS says rhubarb is best used fresh. It can also be frozen, or kept in the fridge for a couple of weeks.

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