Vegetables and fruit

Rhubarb

RheumPolygonaceae
AT A GLANCE
Part shade Water: lots H5down to −15 °C 1–1.2 m tall · 1–1.5 m wide In a pot: yes

Never eat the leaves (only the stalks) — the leaves contain high levels of oxalic acid and are toxic; also avoid harvesting at all in the plant's first year to let it establish.

Care

Water

Consistent moisture, especially in dry spells.

Soil

Fertile, humus-rich, moisture-retentive but well-drained soil; a heavy feeder, benefits from a thick annual mulch of manure or compost.

Pruning

Not applicable in the usual sense; remove any flower spike as soon as it appears, and stop harvesting stalks by around midsummer to let the plant recover strength for next year.

Feeding

Rhubarb is a gross feeder: a thick mulch of well-rotted manure in late autumn and a nitrogen-rich feed as the buds move in spring. Keep the mulch off the crown itself, which rots if buried.

Propagation

Divide the dormant crown in late autumn or winter with a spade, giving each piece at least one fat bud. Do it every five or six years — an old congested crown produces thin, stringy sticks.

Month by month

Months change with the climate: in southern Italy tomatoes go out two months earlier than in England.

  1. MarchTop-dress with well-rotted manure or compost as growth begins. how ›
  2. AprilBegin harvesting stalks by pulling (not cutting) them from the base. how ›
  3. JuneStop harvesting by around midsummer to let the plant build up reserves for next year.

Months based on climate: UK. Your choice stays on this device.

  1. MarchTop-dress with well-rotted manure or compost as growth begins. how ›
  2. AprilBegin harvesting stalks by pulling (not cutting) them from the base. how ›
  3. JuneStop harvesting by around midsummer to let the plant build up reserves for next year.

Months based on climate: Northern Italy. Your choice stays on this device.

  1. FebruaryTop-dress with well-rotted manure or compost as growth begins. how ›
  2. MarchBegin harvesting stalks by pulling (not cutting) them from the base. how ›
  3. JuneStop harvesting by around midsummer to let the plant build up reserves for next year.

Months based on climate: Central Italy. Your choice stays on this device.

  1. FebruaryTop-dress with well-rotted manure or compost as growth begins. how ›
  2. MarchBegin harvesting stalks by pulling (not cutting) them from the base. how ›
  3. JuneStop harvesting by around midsummer to let the plant build up reserves for next year.

Months based on climate: Southern Italy and islands. Your choice stays on this device.

Common problems

Crown rot

How to spot it. Mushy, foul-smelling crown, usually from waterlogging.

What to do. Improve drainage, avoid burying the crown too deep.

How to spot it. Minor, cosmetic spotting.

What to do. Rarely needs treatment.

Slugs

How to spot it. On new spring growth.

What to do. Use barriers or organic control methods.

Questions

Rhubarb: is it hardy?

H5: Hardy in most of the UK, but can struggle in the coldest inland or upland spots. It survives down to −15 °C.

Can it grow in a pot?

Possible in a very large, deep container for a few years, though a permanent bed suits this long-lived plant better.

Rhubarb: when do you prune it?

Not applicable in the usual sense; remove any flower spike as soon as it appears, and stop harvesting stalks by around midsummer to let the plant recover strength for next year.

When do you feed it?

Rhubarb is a gross feeder: a thick mulch of well-rotted manure in late autumn and a nitrogen-rich feed as the buds move in spring. Keep the mulch off the crown itself, which rots if buried. Feeding months, UK: March, November.