Dividing Rhubarb Crowns

Rhubarb is one of the most generous things you can grow, but even a good crown gets tired in time. Dividing it puts that right — and hands you free plants into the bargain. Here is exactly when and how to do it.

Why divide

Rhubarb is a long-lived perennial, but an old crown slowly grows into a congested, woody clump. The centre dies out, the stalks come thinner each spring, and cropping drops off. Dividing every five or six years cuts away the spent middle and gives the healthy outer growth room to power away again.

The second reason is the best one: it is the easiest way to make new plants for nothing. One good crown will give you three or four new ones, so you can fill a row, replace a fading plant, or pass spares to a neighbour. For everything else on growing it well, see our full guide to growing rhubarb.

When to divide

Divide rhubarb when it is dormant, any time from late autumn to early spring — roughly November to March in most of the UK. The leaves have died back by then, the plant has pulled its energy down into the crown, and the buds for next year are sitting ready at the surface.

A mild spell in winter is ideal, as long as the ground is not frozen solid or sitting waterlogged. Avoid dividing in summer: the plant is in full leaf and growth, and it will sulk badly if disturbed.

How to divide

The method is simple and forgiving — rhubarb is tough.

1. Lift the whole crown. Push a fork in well clear of the plant on all sides and lever the entire clump out of the ground. Old crowns are heavy, so dig generously and get under the root.
2. Find the buds. Knock off loose soil so you can see the fat pink or red buds (the "eyes") sitting on top of the crown. These are next year's stalks.
3. Split it up. Drive a spade — or an old knife for smaller crowns — straight down through the crown to cut it into sections. Aim for pieces about the size of your fist, each with at least one healthy bud and a good chunk of root attached. Two or three buds per piece is even better.
4. Discard the dead centre. Throw away any woody, rotten or hollow material from the middle. Only replant firm, healthy outer sections.
5. Replant straight away. Set each piece in soil enriched with plenty of garden compost or well-rotted manure, with the buds just at or barely below the surface — never buried deep, or they may rot. Space new plants about 75–90cm apart, firm them in, and water well.

If you are starting a new bed at the same time, our soil improvement guide covers getting the ground into good heart first — rhubarb is hungry and will repay it.

Aftercare and the first-year rest

Newly divided plants need to put their energy into roots, not stalks. The single most important rule is patience:

• Don't harvest in the first year. Leave every stalk on the plant through its first full season so it can build a strong crown. A light pull or two in the second year is fine; full cropping from the third.
• Mulch in spring. A thick collar of compost or rotted manure around (but not over) the crown feeds it and locks in moisture. A homemade liquid plant feed through the growing season helps too.
• Water in dry spells. Rhubarb hates drying out in its first summer. Keep it watered until it is well established.
• Remove flower spikes. If a stressed plant throws up a tall flower stalk, cut it off at the base so the plant's strength goes into leaf and root.

Forcing the divisions later

Once your new plants are properly established — from their third spring onwards — you can treat them to a little luxury and force an early, tender crop of pale pink stalks. Exclude all light with a bin or a traditional forcing pot in late winter and the plant produces sweet, blanched stems weeks ahead of the main season.

A word of caution: forcing is exhausting for the crown, so never force a young or freshly divided plant, and rest each crown for a couple of years between forcings. Our guide to forcing rhubarb walks through the whole process.

That is all there is to it. With one afternoon's work in the dormant season you rescue a tired plant and end up with several vigorous new ones — free rhubarb for years to come. For everything from planting to picking, head back to the main rhubarb guide, or browse more soft-fruit projects on the grow fruit hub.