Forcing

What forcing actually does

Forcing means tricking a plant into growing earlier — and more tenderly — than it naturally would, by keeping it in the dark. Cover a dormant crown, and the plant still wants to grow, but with no light to grow towards it sends up long, pale, fast-growing stems searching for the sun. Those stems are softer, sweeter and far less stringy than ones grown in the open, and they arrive weeks ahead of the normal season. It's a centuries-old kitchen-garden trick that costs nothing but a bit of patience.

Forcing rhubarb (the classic)

Rhubarb is the plant most UK gardeners force. In January or February, while the crown is still dormant, pop a large upturned bucket, bin or a traditional terracotta forcing jar over it to block out all light. Pack a little straw around or inside the cover for extra warmth if you like. A few weeks later you lift the cover to find slim, pink, beautifully tender stems — ready a good month before the rest of the patch.

The catch is the trade-off. Drawing up that early crop takes a lot out of the crown, so a forced plant needs a full year to recover. The golden rule: never force the same crown two years running. If you grow several crowns, force one each winter and rotate, so each gets two or three seasons to build up reserves between forcings. Rhubarb is a perennial, so a well-rested crown will keep rewarding you for a decade or more.

Chicory and seakale

Rhubarb isn't the only candidate. Chicory (the Belgian or Witloof type) is lifted in autumn, its roots potted up in the dark and kept frost-free, where they push out tight, pale, mild leafy buds called chicons over winter — a welcome fresh crop in the hungry months. Seakale, an old coastal vegetable, is forced much like rhubarb: cover the crown in late winter and harvest the blanched shoots that follow.

Forcing vs blanching

These two get muddled, because both involve keeping light off the plant and both give you paler, milder, more tender growth. The difference is timing and purpose. Forcing is about bringing a crop early, before its natural season. Blanching is about whitening or sweetening growth that's happening in season anyway — earthing up celery or tying up leeks, for instance — with no aim of beating the calendar. Put simply: force for earliness, blanch for tenderness and colour.

Worth trying?

Forcing is one of the most satisfying things a beginner can do — an upturned bucket and a little nerve turn an ordinary rhubarb crown into the first sweet harvest of the year. Just remember to give that crown its year off afterwards. Browse the fruit growing guides and getting started guides for more on growing rhubarb and other early crops.