Picture: Rhubarb In The Garden
Rhubarb (Rheum rhabarbarum) is a robust, hardy perennial plant belonging to the family Polygonaceae, which also includes sorrel and buckwheat. It originates from the cold, mountainous regions of Central Asia — particularly Siberia and China — where it has been used medicinally for thousands of years. Its culinary use in Western cooking, however, is a relatively more recent development, becoming widespread in Europe and North America during the 18th and 19th centuries as sugar became more affordable and its tart stalks found their natural partner in sweetened pies, crumbles, and jams. Today rhubarb is a beloved fixture in kitchen gardens across temperate climates worldwide.
The plant is instantly recognisable by its thick, fleshy stalks — called petioles — which range in colour from deep crimson and vivid red to pale pink and even green, depending on the variety. These stalks are the only edible part of the plant. The leaves, which are large, crinkled, and dramatically broad — sometimes exceeding 60 cm across — are highly toxic to humans and animals due to their very high oxalic acid content and must never be consumed. The plant produces tall flowering stalks in early summer, but these are typically removed promptly by gardeners to direct the plant’s energy back into producing abundant, tender stalks.
Rhubarb is one of the hardiest and most long-lived plants a gardener can grow. Once established, a well-positioned rhubarb plant can remain productive for 20 years or more with minimal intervention. It requires a period of winter cold — known as vernalisation — to thrive, which is why it performs best in temperate and cool climates with reliably cold winters. In regions with mild winters that do not provide adequate chilling hours, rhubarb tends to struggle and produce poorly. Conversely, in climates with harsh, cold winters, it dies back completely to its crown and re-emerges vigorously every spring.
In terms of cultivation, rhubarb is a relatively undemanding plant once established, but it does have a few firm preferences. It thrives in deep, rich, well-draining soil with plenty of organic matter, and benefits greatly from generous annual mulching with well-rotted compost or manure. It prefers a position in full sun, though it will tolerate light partial shade. Good drainage is essential, as waterlogged soil around the crown will cause it to rot. Regular feeding and division every five to eight years — splitting the crown to reinvigorate growth — are the main maintenance tasks required to keep a rhubarb plant productive and healthy over the long term.
In the kitchen, rhubarb is used almost exclusively as a fruit, despite being botanically a vegetable. Its characteristic sharp, intensely tart flavour makes it ideal for use in desserts where it is combined with sugar and often paired with sweeter fruits such as strawberries, apples, and raspberries. Classic rhubarb dishes include crumbles, pies, fools, jams, compotes, chutneys, and cordials. It is also increasingly finding its way into savoury cooking — appearing in sauces and chutneys served alongside duck, pork, and lamb — where its tartness functions much like a citrus element to balance rich, fatty meats.
Beyond the kitchen, rhubarb has a long history in traditional medicine, particularly in Chinese herbal medicine, where various Rheum species have been used for centuries to treat digestive complaints, inflammation, and liver conditions. The roots and rhizomes contain compounds with documented laxative and anti-inflammatory properties. Some gardeners also make use of rhubarb leaves — despite their toxicity for consumption — as a natural pesticide spray, boiling them to release oxalic acid into a solution that can deter certain insect pests. Whether grown for its culinary value, its dramatic ornamental foliage, or its historical significance, rhubarb is one of the most rewarding and enduring plants a gardener can welcome into their plot.
Picture: Rhubarb Seeds
How to Grow Rhubarb from Seed
1. Growing rhubarb from seed is a longer and less predictable route than planting divisions or crowns — which is the method most commonly recommended — but it is perfectly achievable, significantly more economical, and the best option when divisions are not available. The key thing to understand from the outset is that seed-grown rhubarb will not be ready for its first harvest until at least the second or even the third year after sowing, so patience is absolutely essential.
2. Choose your seeds carefully. Many rhubarb varieties sold as named cultivars — such as ‘Timperley Early’ or ‘Victoria’ — do not come reliably true from seed, meaning seed-grown plants may vary somewhat in stalk colour, thickness, and flavour from the parent plant. For the most consistent results, purchase fresh seeds of a named seed-strain variety from a reputable supplier, or sow seeds collected from a known and productive plant in your garden.
3. Sow seeds indoors in late winter or early spring, approximately 8 to 10 weeks before your last expected frost date. Rhubarb seeds can also be sown outdoors directly in early spring once the soil is workable, but starting them indoors gives you greater control over germination conditions and produces stronger seedlings that are better equipped to survive their first outdoor season.
4. Use a good-quality, fine-textured seed-starting or multipurpose potting mix. Fill small individual pots or seed cells with the moist mix and sow one or two seeds per cell at a depth of about 1 to 2 cm (half to three-quarters of an inch). Firm the surface lightly after sowing to ensure good contact between the seed and the growing medium.
5. Soak seeds in warm water for 2 to 4 hours before sowing to soften the outer seed coat and encourage faster, more uniform germination. Rhubarb seeds have a somewhat papery outer casing that can slow moisture uptake, and a brief pre-soak is a simple and effective way to improve germination speed and overall success rates.
6. Maintain soil temperatures of around 18 to 21°C (65–70°F) during the germination period. A seedling heat mat placed beneath the trays is helpful, especially when sowing in late winter when indoor temperatures can be inconsistent. Rhubarb does not require very high temperatures to germinate, but consistent moderate warmth will produce the most reliable results.
7. Expect germination within 7 to 21 days under warm, moist conditions. Rhubarb seeds germinate at a moderate and fairly reliable rate when fresh, though older seed may take longer or germinate less uniformly. Keep the growing medium consistently moist but not waterlogged during this period, and check daily for emerging shoots.
8. Provide seedlings with plenty of light as soon as they emerge. Place trays on a bright south-facing windowsill or under a grow light for 12 to 14 hours per day to prevent the seedlings from becoming etiolated — pale, weak, and stretched towards the light source. Strong, stocky seedlings at this stage will establish far more successfully outdoors later in the season.
Picture: Rhubarb Seeds
9. Thin or pot on seedlings once they develop their first set of true leaves. If two seeds were sown in the same cell, remove the weaker of the two by snipping it at soil level. Transplant seedlings into individual 9 to 12 cm pots filled with a richer potting mix to give their roots room to develop and to support the rapid growth that follows the appearance of the first true leaves.
10. Begin a gentle feeding routine once seedlings are growing actively in their individual pots. Apply a balanced liquid fertiliser at half the recommended strength once every two weeks. Rhubarb is a heavy feeder once mature, and introducing nutrients gradually at the seedling stage — rather than all at once — builds a strong, healthy plant without the risk of burning delicate young roots.
11. Do not rush transplanting outdoors. Rhubarb seedlings must be properly hardened off over a period of 10 to 14 days before being moved to the garden permanently. Begin by placing them in a sheltered outdoor spot with indirect light for a few hours per day, gradually increasing their exposure to direct sun, wind, and cooler outdoor temperatures over the two-week period.
12. Choose the planting site carefully, as rhubarb is a long-term resident that may occupy the same spot for two decades or more. Select a position in full sun with deep, rich, well-draining soil. Avoid low-lying areas where water pools in winter, as prolonged waterlogging will rot the crown. Prepare the bed thoroughly by digging in generous quantities of well-rotted compost or aged manure to a depth of at least 30 cm.
13. Transplant seedlings to the garden in spring once all frost risk has passed and soil temperatures have begun to warm. Space plants at least 90 cm to 1 metre apart in all directions — rhubarb grows into a large, spreading plant and needs ample room for its substantial crown and dramatic foliage to develop fully without crowding.
14. Water newly transplanted seedlings deeply and consistently for the first several weeks until they are fully established. Rhubarb prefers evenly moist soil throughout the growing season, particularly during dry spells in summer, though it will tolerate short periods of dryness once mature. Apply a thick layer of mulch — such as well-rotted compost, straw, or wood chips — around the base of each plant to help retain soil moisture and suppress weeds.
15. Remove any flower stalks that appear during the first two or three years of the plant’s life. When rhubarb bolts and produces its tall flowering and seed heads, it diverts enormous amounts of energy away from crown and leaf development. Cutting these off promptly at the base redirects that energy back into building a strong, productive plant that will reward you with a far better harvest in future seasons.
16. Resist the temptation to harvest any stalks during the plant’s first full growing season, and harvest only very lightly — just two or three stalks at most — in the second year. Allowing the plant to grow largely undisturbed during these early years is what enables it to build the strong, deep root system and large crown that will sustain generous annual harvests for many years to come. From the third year onwards, you can begin harvesting freely from late spring through midsummer, pulling stalks cleanly from the base rather than cutting them, and leaving at least four to five stalks on the plant at all times to maintain its vigour.