Rhubarb are an allotment ‘must’ – a delicious early spring crop with tender pink stalks. Yum! Even better, rhubarb is easy to grow and once established tends to take care of itself.
Rhubarb is an ancient plant with records of its growth and use as medicine 5,000 years ago in China. It came to Europe along the Silk Road in the 1300s but was not cultivated in Europe until the early 1600s and was not considered a culinary (as opposed to medicinal) plant until the late 1700s. By the 1800s commercial growing of rhubarb had taken off in the UK. (RHS, The Garden, March 2019, p.45)
- All varieties develop a deep root system & grow best in fertile, partially shaded, free-draining soil.
- Dig over your plot 4 weeks before planting, removing any stones you find and adding as much organic matter as possible. Rhubarb loves rich kitchen compost and rotted manure.
- Plant ‘crowns’ that have been divided from strong, disease-free plants in late autumn to early winter.
- Keep in mind that many varieties grow to be very large plants and require a lot of space.
- The depth should be such that the top of the plant is at, or just below the soil surface. Gently firm soil and water well.
- Spacing between plants should be about 75cm (30in) for smaller varieties, and up to 120cm (48in) for larger varieties.
- Allow rhubarb to establish for one year before taking your first harvest. Select three of the largest stalks, waiting for the leaves to fully open before pulling from May to August.
- For established plants, harvest early from March, with a main season being May to end July. Only harvest a third of the plant at a time. Later in the season stop picking to allow the plants to build up reserves for next year.
- Add a spring mulch of compost. An occasional liquid feed or scattering of organic chicken manure pellets from late spring to autumn gives plants a boost.
- At the end of the summer, after the leaves have died down, spread a new layer of compost around the plant to conserve water, feed the roots and suppress weeds.
- Dead-head flowers immediately after they appear, as allowing flowers to set seed will weaken the plant.
To keep the plants healthy, rhubarb should be divided every 5 or 6 years during winter, when dormant. Each plant can be split into 3 or 4 separate crowns with a spade. Make sure each crown has an ‘eye’, or a large bud, that will provide next year’s shoots. Dig out a hole slightly larger than the divided plants and place the crown in the hole with its roots facing downwards. The top of the crown should be 2.5cm (1 inch) below the soil surface. Mark where the crown has been planted with a cane or stones until new shoots appear above the soil surface in late February or March.
Outdoor forcing is a simple process that provides an earlier harvest of sweet tender stems. For forcing outdoors, cover plants with a container or large pot to exclude the light. Place the cover over the rhubarb as soon as it begins to show signs of growth. Only force a rhubarb once every 4 years to avoid exhausting it. Once forced stalks have been harvested, allow plants to recover for the rest of the growing season. (I don’t bother forcing rhubarb as normally it’s tender enough if harvested in young growth.)
We have a variety of rhubarb planted in the long plot in the back patch. One or two of them are quite tough stemmed and I don’t like them much, but we do have a Timperley Early (RHS AGM) which is consistently tender & delicious. Timperley rhubarb are an early variety with thick tender stems and produce a high yield. This type of rhubarb was bred for forcing. It performs very well outside, but has even better colour when forced.
At the allotment R divided his large clump of rhubarb and gave us a couple of sections of root. These I had ‘heeled’ into the allotment but never moved them. Early April 2020 we harvested from the allotment patch, then watered well and dug these out, to transplant into a newly dug bed in the back patch. Much as we love rhubarb it’s a better plant to have in the back patch, taking care of itself. We won’t harvest anymore from that new bed, and probably shouldn’t harvest it too much next spring either (but probably will as these plants are quite strong and vigorous).