Rheum Plant Growing & Care Guide for Gardeners
Article by Dean Ravenscroft, Ph.D. - Updated 6th Nov 2023
In this Gardener's HQ guide, we'll explore cultivating Rheum plants in your garden, indoor spaces, and other settings.
- Plant Characteristics: Rheum is celebrated for its large, bold leaves and strikingly architectural stalks. It can be used to provide a dramatic backdrop in garden settings.
- Ideal Growing Conditions: Prefers deep fertile soil, cool climates, and partial shade locations that will shield its leaves from the scorching sun.
- General Care: Requires regular watering and a rich feeding regime to support its vigorous growth. Provide a mulch to help retain moisture.
- Tips for New Gardeners: Rhubarb is an easy plant to grow for beginners, as it thrives with basic care, so long as the growing conditions are met. Monitor for slugs and snails, as they are attracted to its succulent stems.
Rhubarb, Sorrel Rhubarb: Cultivation & Garden Use
Rheum are hardy perennials that are often used in cookery. They are large plants, that can reach from three to eight feet (90 cm to 2.5 m) in size.
Rheum plants have large toothed leaves. They carry small white flowers atop edible stalks. Some common names for members of the Rheum plant genus are Rhubarb and Sorrel Rhubarb.
Rheum (Rhubarb) by OliBac.
If you are planning to grow Rhubarb for use in cooking, then it is best to grow from rootstock as these will provide better flavor than seed grown rhubarb.
The Rhubarb stalks can be harvested from the second year of growth onwards. They should not be harvested later than July.
Commonly Grown Rheum Species Photographs and Plant Identification
Rheum palmatum
Rheum palmatum (Ornamental Rhubarb / Chinese Rhubarb), photograph by Leonora (Ellie) Enking; CC.
Rheum rhaponticum
Babij; CC.
Rheum officinale
Rheum officinale (Indian Rhubarb), picture by Laurent Neyssensas; CC.
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Rheum Growing and Care Guide
- Common Names: Rhubarb, False rhubarb, Sorrel rhubarb.
- Life Cycle: Hardy perennial.
- Height: 36 to 96 inches (90—240 cm).
- Native: Europe, Asia.
- Growing Region: Zones 5 to 9.
- Flowers: Summer.
- Flower Details: Green-white, rose, red. Small.
- Foliage: Herbaceous. Triangular. Large. Toothed. Grown for their tart tasting stalks, and for ornamental purposes.
- Sow/Growing Outside:
Do not grow from seed if growing for culinary purposes.
Seeds: 1/4 inch (6 mm). About one month before the last frost.
Roots: Include buds. 1 to 2 inches (3 to 6 cm). - Sow/Growing Inside: Germination time: three to six weeks. Temperature: 63 to 65°F (17—18°C). Ten weeks in advance. Transplant outdoors when there is still a chance of a light frost or towards the end of autumn. As there is a large variation in size space at 12 inches (30 cm) to 60 inches (150 cm) apart depending on size. Ornamental varieties are usually grown singly.
- Requirements and care: Full sunlight or light shade. Deep soil. Rich and moist soil. Mulch to maintain moisture. Provide a complete spring feed, and a weak feed every two weeks thereafter through the growing season. Regular watering during dry periods. Water during prolonged dry spells. Regular watering during periods of growth. Cut back flower inflorescences to the ground once blooming has completed in the first year. Remove inflorescences as they appear in subsequent years. Do not harvest stalks in the first year. Do not harvest later than mid-summer (late July in the Northern hemisphere). Propagate: by dividing by dividing in the spring.
- Family: Polygonaceae.
- Closely Related Species: Knotweed.
- Miscellaneous: Rhubarb has laxative properties. Extracts of Rheum officinale are used to create the arthritis medication rheum. Although Rhubarb is a vegetable, with the leaf petiole/stalk being eaten, it is classified as a fruit in the USA. Takes from two to five years to reach full height.
How to Grow Rhubarb
It is best to grow Rhubarb from root stock if you plan to use them for culinary purposes. These these should be planted at about 3 to 5 cm (1 to 1 1/2 inches) deep.
If growing Rhubarb and other Rheum members as decorative plants, then they can be grown from seed.
Plant the seeds about 6 mm (1/4 inch) deep. Do so about a month before the last frost of spring is expected.
Rheum can be very big plants, so space them from 40 cm (16 inches; small varieties) to 1.5 m (5 feet; larger Rheum members) apart.
Rhubarb can grow in either sunny or partially shaded parts of the garden. They prefer a rich and moist soil. It is important that the soil that Rheum plant species grow in is very deep.
If starting Rhubarb off indoors, then do so about 2 months in advance. Plan to transplant out in late autumn, or before the last frost of spring.
It should take from three to six weeks for Rheum to germinate, at 15 to 18 degrees Celsius (59 to 64°F).
Caring for Rhubarb and Other Rheum genus Members
To grow Rhubarb and other Rheum species successfully takes a little effort.
They should be fertilized every two weeks with a weak fertilizer solution.
Apply a mulch to protect them from heat, and water frequently to keep the soil moist.
If you require more Rhubarb plants, then they can be propagated by division in the spring.
Common Questions
How many members does the Rheum genus contain?
The Rheum genus, most famously associated with Rhubarb, contains about 60 species.
Do Rheum members make a good garden or landscaping plant?
Yes, Rheum plants are excellent for the garden. Some species have edible stalks, while others have decorative leaves and flowers, adding interest to the landscape.
Which Rheum species are most frequently grown by gardeners?
The most commonly grown species is Rheum rhabarbarum (Garden Rhubarb), often cultivated for its edible stalks in a vegetable or herb garden.
Are Rheum plants fragrant?
While Rheum plants have distinct, large foliage, they are not particularly noted for their fragrance.
What is the perfect location to grow Rheum?
Rheum prefers a sunny to partially shaded location with well-drained, fertile soil. Rhubarb plants, in particular, like a cooler climate.
Is Rheum invasive in the USA, if so in which states?
Currently, Rheum species are not considered invasive in the USA.
How do I remove Rheum plants from my garden?
To remove Rheum, dig up the entire plant, being sure to remove all of the thick, deep roots to prevent regrowth.
Summary
The Rheum genus includes plants known as rhubarbs, with the garden rhubarb being the most familiar species. Native to Asia, these perennials are known for their large leaves and thick, colorful stalks.
Rhubarbs are hardy plants that prefer full sun to partial shade and rich, well-drained soil. They are best planted in early spring and are quite low maintenance once established, making them a popular choice for beginner gardeners.
I hope that you enjoyed this guide on how to grow Rheum plants. You may also enjoy the following Gardener's HQ growing guides: How to grow Prickly Rhubarb, Chinese cabbage, Lima Beans, and Polygonum plants.
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