Though technically a vegetable, rhubarb is generally known as a fruit because it’s a popular ingredient in desserts such as crumbles and pies.
It’s a perennial crop, which means it harvests for more than one season and could last for around ten years, and with a little care you can collect lovely succulent stems on healthy plants.
Rhubarb is best planted as ‘crowns’ - these are sections of a much larger plant; these ‘crowns’ are divided from the mother plant in autumn to ensure that the crown you receive is strong and healthy.
We recommend that these rhubarb crowns are grown on in pots for around one month before planting them out to give them the best start. Place the crowns into a large pot of compost with the growing point level with the surface of the soil. Keep the compost moist but avoid overwatering to prevent waterlogging. If your proposed planting site gets very wet through the winter, then the crown can be left in this pot until spring. Place in a shady part of the garden and water through the winter during dry spells. From around March, there should be some small signs of growth from the crown, this is now the time to plant it in its final position.
When to plant rhubarb crowns
The best time to plant rhubarb crowns is from October to early December, although they can also be planted in the first three months of the year.
Rhubarb crowns don’t take to being planted in very wet or waterlogged soils.
How to plant rhubarb crowns
Rhubarb grows best in a sunny site with well-draining soil - dig plenty of well-rotted manure into the soil, aiming for around 2 buckets per square metre. You should choose a spot where rhubarb hasn’t been grown for the last 6 years and avoid locations which are susceptible to frost as this can damage the stems.
Create a hole in the soil for each crown and place so it sits just below the surface of the soil (around 2cm), but with the top of the crown still visible, and spread the roots out. Fill the hole and place plenty of compost around the crown. Space the crowns around 75-90cm (30-36in) apart and leave 30cm (12in) between rows. Water the rhubarb crowns after planting - the soil should then remain naturally wet through the autumn and winter months. Water well in dry conditions.
Rhubarb can also be planted in large pots which are at least 50cm (20in) deep and wide. If planting in pots, ensure the soil is kept moist, especially during dry spells.
How to care for rhubarb
How to water rhubarb:
Give rhubarb a good watering after planting in autumn and winter, and then the soil should remain naturally wet through these months. Water well in dry conditions.
How to feed rhubarb:
Feed plants in summer with a general fertiliser, preferably one that’s high in nitrogen. Adding mulch to the soil, like manure, in the plant’s first February or March will conserve moisture in the soil. The secret to success with Rhubarb is a plentiful supply of well-rotted manure placed around the crown, right through the growing season.
Rhubarb does not need much pruning or training – just remove any flowers as soon as they appear on the plant.
How to harvest rhubarb
Rhubarb crowns shouldn’t be harvested in the first season – any stems that do grow should be allowed to die back naturally. You can harvest stems in the plant’s second April.
When you’re ready to harvest, pull the stem up with your hand, close to the base of the plant which stays in the soil, and twist slightly as you pull. The more you harvest, the more stems you’ll get. Remember to add well-rotted manure, especially after a good harvest. Leave at least three to five stems per harvest and stop harvesting by July, to ensure you get an abundant crop each season.
During late autumn, allow the leaves to die down but clear around the crown to allow the frost to penetrate the crown. This ensures the plant with be full of vigour again once the spring returns..
You can selectively ‘force’ some rhubarb stems for sweeter and paler stems. Place an upturned dustbin (or something similar) over the plant to create darkness and in around six weeks, the stems should be harvestable. This is especially affective in the early spring and will provide juicy, sweet and tender stems. This technique should only be used once every two years.