Rhubarb
Rheum Rhabarbarum
Rhubarb, or Rheum rhabarbarum, is a perennial vegetable known for its tart stalks, often used in pies and desserts. Originating from Asia, it thrives in cooler climates and is cherished for its unique flavor and vibrant appearance in gardens.
Everything it needs
9 essentials at a glance
Watering
Rhubarb prefers consistently moist soil, especially during its growing season.
Water deeply once a week, increasing frequency during hot, dry spells. In cooler months, reduce watering to every 10-14 days. Signs of over-watering include yellowing leaves and root rot, while under-watering can cause wilting and leaf curling.
Light
Rhubarb thrives in full sun, requiring at least 6-8 hours of direct sunlight daily.
Ideal placement includes a sunny garden bed or a spot that receives morning sun and afternoon shade in extremely hot climates. It can tolerate partial shade but may produce less robust stalks.
Soil
Rhubarb prefers rich, well-draining soil with a pH range of 6.0 to 7.0.
A loamy soil composition enriched with organic matter, such as compost or well-rotted manure, is ideal. Ensure good drainage to prevent root rot, as rhubarb does not tolerate soggy conditions.
Humidity
Rhubarb enjoys moderate humidity levels, ideally between 40-60%.
To increase humidity, consider mulching around the base of the plant or misting the leaves during dry spells. Signs of low humidity include leaf curling and browning edges.
Temperature
Rhubarb thrives in cooler climates, with an ideal temperature range of 45-75°F (7-24°C).
It is hardy in USDA zones 3-8 and can tolerate frost, but extreme heat above 85°F (29°C) can stress the plant. In winter, it benefits from a layer of mulch to protect the roots.
Fertilizing
Use a balanced fertilizer with an NPK ratio of 10-10-10 or a slow-release organic fertilizer.
Fertilize in early spring as new growth appears, and again mid-summer. Signs of nutrient deficiency include stunted growth and pale leaves, indicating a need for additional feeding.
Pruning
Pruning is minimal for rhubarb; however, it is essential to remove flower stalks as they appear to encourage leaf and stalk growth.
Use clean, sharp pruning shears for cutting. Dead leaves should also be removed to prevent disease and promote healthy growth.
Repotting
Rhubarb is typically grown in the ground, but if grown in pots, repot every 2-3 years or when it outgrows its container (usually when roots are visible at the drainage holes).
Choose a pot that is at least 2-3 inches larger in diameter. Repot in early spring before new growth starts.
Propagation
Rhubarb can be propagated through division or seed.
For division, in early spring or fall, carefully dig up the plant and separate the crowns, ensuring each division has at least one bud. Replant immediately in well-prepared soil. If using seeds, sow them indoors 8-10 weeks before the last frost, then transplant outdoors after the danger of frost has passed.
When it's unhappy
Yellowing leaves
Why it happens
Often caused by over-watering or nutrient deficiency.
How to fix it
Check soil moisture and reduce watering if necessary. Fertilize with a balanced fertilizer if nutrient deficiency is suspected.
Wilting leaves
Why it happens
Typically a sign of under-watering or heat stress.
How to fix it
Increase watering frequency and provide shade during the hottest part of the day.
Flowering
Why it happens
Occurs when the plant is stressed or reaching maturity.
How to fix it
Remove flower stalks as soon as they appear to redirect energy back to leaf and stalk production.
Root rot
Why it happens
Caused by overly wet soil conditions.
How to fix it
Ensure proper drainage and reduce watering. If root rot is severe, consider replanting in fresh soil.
Pests (e.g., aphids)
Why it happens
Common in stressed plants or poor growing conditions.
How to fix it
Inspect regularly and treat with insecticidal soap or neem oil if infestations occur.
Care through the year
Spring
In spring, prepare the soil by adding compost and fertilizer as new growth appears. Water regularly to keep the soil moist and remove any flower stalks that may develop.
Summer
During summer, maintain consistent watering and apply mulch to retain moisture and suppress weeds. Fertilize again mid-summer to support ongoing growth.
Fall
In fall, reduce watering as the plant prepares for dormancy. Cut back any dead foliage and apply a layer of mulch to protect the roots during winter.
Winter
In winter, ensure the rhubarb is mulched to protect against freezing temperatures. Avoid watering unless there is a prolonged dry spell.
Toxicity & Safety
Rhubarb leaves are toxic to pets and humans due to high levels of oxalic acid, which can cause nausea, vomiting, and difficulty breathing if ingested. The stalks are safe to eat when cooked, but should always be consumed in moderation.
Good to know
Why are my rhubarb leaves turning yellow?
Yellowing leaves in rhubarb can indicate over-watering or a nutrient deficiency. Check the soil moisture and adjust your watering schedule accordingly, and consider fertilizing if the soil lacks nutrients.
How often should I water my rhubarb?
Water rhubarb deeply once a week, increasing frequency during hot, dry spells. Ensure the soil remains consistently moist but not soggy to promote healthy growth.
Can I grow rhubarb in a pot?
Yes, rhubarb can be grown in pots, but ensure the container is at least 18 inches deep and wide. Repot every 2-3 years to provide adequate space for root growth.
When is the best time to harvest rhubarb?
Harvest rhubarb stalks in late spring to early summer, once they reach at least 12 inches in length. Always leave some stalks on the plant to allow for continued growth.
Is rhubarb toxic to pets?
Yes, rhubarb leaves are toxic to pets and humans due to high oxalic acid content. The stalks are safe to eat when cooked, but should be consumed in moderation.
How do I prevent my rhubarb from flowering?
To prevent flowering, ensure your rhubarb is healthy and well-watered. Remove any flower stalks immediately to redirect energy back into leaf and stalk production.
What soil type is best for rhubarb?
Rhubarb thrives in rich, well-draining soil with a pH of 6.0 to 7.0. Incorporate organic matter like compost to improve soil structure and fertility.
Grows well with
Related care guides
Explore remedies
Track this plant in your garden.
Set care reminders, log growth, and join a community of plant lovers.