Rhubarb crops reliably every year with little maintenance
The leaf stalks are usually picked during spring and early summer, but plants can be covered with large pots or
Some initial patience is required, as you shouldn’t harvest any stems in the first year after planting, and only a few in the second, to allow the plant to get well established. In the third year, you can harvest normally, taking up to a third of the stalks at any one time.
Rhubarb is traditionally eaten as a dessert, baked in pies and crumbles, but you can use your plentiful harvests in many more ways, including tangy chutneys and savoury sauces.
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Rhubarb stems range from deep burgundy to light pink, depending on the variety
The RHS Garden Wisley holds the National Collection of rhubarb, comprising over 100 varieties, many of historical interest. Make a visit in spring or summer to see the different varieties and how they grow. You can also see a wide range of vegetables and fruit at all the RHS gardens, so do visit for lots of inspiration and growing tips.
What and where to buy
Bare-root rhubarb crowns are cheaper than plants in containers, but are only available during the dormant season. Seeds are an even cheaper option, but seedlings are trickier to look after and take longer to reach cropping size.
Before buying, it’s also worth asking fellow gardeners if they have any rhubarb plants to spare. Established clumps need dividing every few years, in late autumn or winter, to keep them cropping well. This process produces several new plants each time – ideal for sharing with friends.
Growing rhubarb from seed is not the easiest or quickest option, but it is the cheapest way to produce lots of plants. Seed-raised plants are slower to get established than rhubarb bought as bare-root or potted plants, which already have strong roots. They are also more variable in quality, as bought plants are produced by division so are exact clones of their parent.
Sow rhubarb seeds in March or April, either indoors or in the ground. Outdoors, sow them 2.5cm (1in) deep, then thin out the seedlings to 15cm (6in) apart. Indoors, use small pots or modules filled with peat-free seed compost. Transplant the young rhubarb plants into their final position in autumn or the following spring.
Rhubarb grows best in an open, sunny site with fertile, moist but free-draining soil. It will also cope in light shade. Avoid ground that gets waterlogged, as plants are liable to rot. If your soil is heavy, plant in raised beds or large containers. Although rhubarb is very hardy, it’s best not to plant it in a site prone to late frosts, as the young stems may be damaged. Alternatively, choose a later-cropping variety.
Rhubarb can be bought either in pots or as dormant bare-root plants known as crowns. Both are planted in a similar way, although the timing may vary:
- Containerised plants – are sold all year round for planting at any time, although spring or autumn are best. Avoid planting in very hot, dry weather
- Bare-root crowns – are only available from mid-autumn to early spring and should be planted straight away, ideally in November or December
Prepare the planting site by digging in two bucketfuls of well-rotted manure per square metre/yard. Then dig a planting hole that’s just a little larger than the roots. Position the plant so the tip of the crown, or the point where the leaves emerge, is just above the soil surface. Back-fill around the roots with soil, firm in, then water well. If planting more than one, space them 75–90cm (30–36in) apart. For more planting tips, see our guide below.
Planting in a container
If your soil is heavy or waterlogged, or you’re short on soil space, you can grow rhubarb in a large container, at least 50cm (20in) deep and wide. Make sure there are plenty of drainage holes and choose a peat-free soil-based compost. Position the plant so its main growth bud or the point where the leaf stalks emerge is just above the compost surface. See our guides below for more tips.
Once established, rhubarb needs little maintenance, apart from removing flower stems and faded leaves, and mulching in spring. For a prized crop of early, sweeter stalks, you can blanch (or force) them in winter. Clumps should also be divided once they become overcrowded.
Watering and feeding
Once established, rhubarb rarely needs watering, but young plants and those in containers do need regular attention:
Newly planted rhubarb – water regularly throughout its first growing season, until well rooted
Established rhubarb plants – water only during prolonged dry periods in summer or in very light, free-draining soil. Growth will slow down and even stop if conditions are too hot and dry
Rhubarb in containers – water regularly throughout the growing season, as the compost will dry out quickly. Keep it moist but never waterlogged. In winter, make sure rain drains out freely by raising the pot up on ‘feet’ or bricks, or move it to a spot that’s sheltered from heavy downpours. The roots can rot in waterlogged compost
To boost growth, apply a general fertiliser in spring or summer.
After you have harvested the first flush of blanched stems, remove the covering and allow the plant’s subsequent stems to develop normally. Avoid forcing the same plant in consecutive years.
Rhubarb clumps often send up one or more large flower stems in summer – remove these at the base as soon as they appear, to prevent them weakening the plant. Some varieties are more prone to flowering than others, and it’s more common in a wet summer or if a high nitrogen feed has been overused.
Dividing mature plants
Large clumps of rhubarb should be divided every five years or so, especially if the leaves are overcrowded or growth has become weaker. This will give you several vigorous new plants for your own garden or to share with friends, but only propagate from strong healthy plants to ensure they are virus-free.
Dig up the entire clump while dormant, between mid-autumn and early spring – ideally in November. Use a spade or an old kitchen knife to slice it into several smaller sections, each with a portion of the rhizome (thickened root) and at least one growing point or bud. Sections from the outer part are better than the centre of old plants. Discard any weak or decayed parts. Replant the root sections straight away or wrap them in damp sacking for a short time if necessary.
In autumn, allow the leaves to die back naturally, then cut them all away to expose the growing points to winter cold. The faded leaves can be added to the compost bin – there’s no need to worry about the poisonous oxalic acid they contain, as this breaks down during decomposition.
Rhubarb is best used fresh, but can be frozen or stored in the fridge for a couple of weeks
Most varieties can be harvested from late April or May, while early varieties can be picked from March or April. Although the stems remain edible and tasty through to mid-summer, it’s best to stop harvesting in June, or at least only take a few after then, so you don’t weaken the plant. By mid-summer the stalks usually become tough and stringy.
To harvest, choose a young stalk about 30cm (1ft) long, with a leaf that has only just fully opened. Hold the stalk at the base and twist gently to ease it out of the ground. Try to avoid snapping it off, and don’t cut it, as you’ll leave a stump that is prone to rotting. Then remove the leaf, which is not edible, and add it to your compost bin. Only ever take about a third of the plant’s stems, so there are plenty of leaves left to keep it in active growth.
Some people worry about increasing levels of oxalic acid in rhubarb as the season progresses. However, this build-up is mostly in the leaves, which you don’t eat, and the amount in the stems is insufficient to have a toxic effect.
Rhubarb is generally a robust, hardy and healthy plant that can live for at least ten years, and can be kept going far longer if divided regularly. There are only a few problems to look out for:
- slugs and snails may damage young shoots, especially tender shoots under forcing jars – see our tips on how to stop slugs and snails
- late frosts can damage young shoots, so cover with straw (or similar), if freezing temperatures are forecast
- rotting in damp conditions, especially in winter – avoid planting rhubarb in a poorly drained site that gets waterlogged, and make sure plants in containers don’t sit in trays of water. If you notice areas of die-back, cut these out promptly before the rot spreads and kills the whole plant
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