Rhubarb is a cool-weather crop that will bolt, producing flowers rather than thick, juicy stems, in hot conditions. With rhubarb season officially over in the UK, it’s a good time to work on strengthening your rhubarb patch. To ensure it bursts into growth next spring and summer, there’s one simple pre-winter task that gardening experts say you shouldn’t skip.
The simple task is not to pick, prune or force rhubarb, but to divide the crowns into smaller plants. Caledonian Horticulture and the Royal Horticultural Society (RHS) both recommend dividing established plants to rejuvenate tired crowns and propagate new ones. Older crowns get congested, buds compete, and yields slide. By separating robust sections and replanting them, you reset the plant’s vigour and expand your homegrown rhubarb harvest at the same time.
It’s easy to divide rhubarb crowns when you know exactly the criteria for doing so, and it is very simple, according to Caledonian Horticulture.
The gardening experts said: “Dividing rhubarb plants every five to seven years is essential to maintaining their health and productivity.
“Division rejuvenates older plants, allowing them to continue producing strong, healthy stalks, and also gives you the opportunity to propagate new plants.”
You can estimate a rhubarb plant’s age by its vigour, but a more straightforward method is to look for signs of overcrowding and declining productivity, such as numerous thin stalks.
Most rhubarb plants should be divided every five years, so if yours has been producing poor yields of thin stalks over several seasons, it is likely mature enough for division.
On timing, rhubarb is best divided in early spring, just before new growth begins, or in late autumn when the plant is dormant.
Given that November is considered late autumn in the UK, there is plenty of time to tend to rhubarb plants in the garden. And you don’t need any special tools to successfully propagate new plants.
How to divide rhubarb crowns
Locate your rhubarb crown and use a sharp spade or knife to divide it into sections. Each division should have at least one or two buds and a healthy portion of root, notes Caledonian Horticulture.
Remember that having more buds results in a larger divided plant.
Discard any weak or decayed plants before replanting the small portions in prepared soil, spacing them 90cm apart to allow for growth. If you don’t want to plant them straight away, the RHS suggests placing the divisions in damp sacking for a short time.
To grow a larger plant, replant small root divisions with one bud in the same planting spot.
Water them thoroughly to help them establish in their new location. Rhubarb likes a sunny spot, cool climates, and well-drained soil.
Gardeners are advised to hold off harvesting in the first growing season after division, allowing the plants to replenish their reserves.
The year after, you can harvest the rhubarb fruit lightly, then return to normal.
Rhubarb plants should be mulched throughout the spring to ensure a healthy crop. However, it is essential to mulch around, rather than on top of, the crown to prevent crown rot.
