Why is my rhubarb thin and spindly?

Rhubarb is close to indestructible, which is why so many gardens have a crown that has been sitting in the same spot for twenty years producing progressively thinner sticks. It is not diseased and it has not run out of enthusiasm; it is congested and hungry, and both are fixable in an afternoon in winter.

Step by step

1. Work out how old the crown is.Rhubarb needs dividing roughly every five to ten years. A crown with a dead woody centre, a ring of growth round the outside and lots of thin stalks is telling you clearly that it is overdue.
2. Divide it in winter while it is dormant.Between late autumn and late winter, when there is no top growth. Lift the whole crown with a fork, and cut it into pieces with a spade or an old knife. Each piece needs at least one fat visible bud and a good chunk of root.
3. Keep the outer pieces and discard the middle.The vigorous growth is round the outside. The old woody centre is spent — compost it.
4. Replant with the buds at soil level.Prepare the new position with plenty of well-rotted manure, plant so the buds sit just at the surface, and firm in. Planting too deep on heavy soil causes the crown to rot.
5. Do not pick at all in the season after dividing.The divisions need a full year to establish. Picking straight away is how a newly divided crown ends up as thin as the one you replaced.
6. Feed and mulch heavily every year.Rhubarb is a gross feeder. A thick mulch of well-rotted manure or compost around the crown every autumn — around it, not over the buds — is worth more than any liquid feed.
7. Check for shade and competition.Rhubarb wants an open sunny position. A crown under a tree, against a shaded fence or being invaded by grass will always be thin. Clear a good circle around it.
8. Stop picking by midsummer.Pulling stalks into late summer prevents the plant rebuilding. The traditional cut-off is around the end of June, and it exists for a reason.
9. Never strip the crown.Take no more than about half to two-thirds of the stalks at any one time, always leaving several to keep the plant working. Pull with a twist rather than cutting.
10. Remove flower spikes as soon as they appear.A flowering crown diverts a large amount of energy into seed. Cut the spike out at the base immediately.

Tips

• One good crown feeds a household. Two is generous. Dividing an old plant usually gives you several pieces, so pass the spares on.
• Rhubarb tolerates a wide range of soils but hates waterlogging. On heavy wet ground plant it on a slight mound.
• The first stalks of the year are always the best — thick, tender and pink. Later stalks are coarser, which is another reason for the midsummer cut-off.
• Do not cut rhubarb stalks with a knife; pull them with a twist so they come away cleanly at the base. A cut stub rots back into the crown.
• Rhubarb leaves are toxic and should never be eaten, but they are fine on the compost heap.

Common mistakes

• Leaving a crown undivided for decades — It becomes congested, the centre dies, and every bud competes. This is the single commonest cause of thin sticks.
• Picking a newly planted or newly divided crown — It has no reserves to draw on and never establishes properly. One season of patience decides the next decade.
• Picking into late summer — The plant needs the second half of the season to build reserves for next spring. Late picking produces next year's thin sticks.
• Planting the crown too deep — The buds rot in wet soil. They should sit at the surface, not under it.

Keeping on top of it

• Mulch with well-rotted manure or compost around the crown (annually, in autumn)
• Remove flower spikes at the base (as they appear, spring and early summer)
• Lift and divide the crown (every 5–10 years)
• Clear grass and weeds from around the crown (twice a year)

Questions people ask