Rheum x hybridum, R. rhabarbarum
Rhubarb is a beautiful, easily cultivated perennial with large, ruffled leaves and tall stalks of pink or scarlet with a delicious, sharply tart flavor.
The pretty stalks of this herbaceous vegetable (or fruit, if you prefer) are harvested throughout spring and summer and pack some serious pucker power!
When sweetened, the tangy taste is mouth-wateringly ideal for use in a range of baked goods as well as compotes, preserves, and relishes, or simply enjoy it stewed.
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An early arrival in cool spring temperatures, rhubarb is popular in temperate regions where it grows vigorously from underground rhizomes, and it needs a cold spell for leaf buds to properly set.
This makes it ideal for northern gardens where these plants have long been a staple in backyard beds, farmyard gardens, and vegetable plots.
They do struggle in hot temperatures, but rhubarb can be grown in southern gardens as a winter annual.
The red-veined leaves make beautiful foliage plants and these are avoided by herbivores like deer and rabbits. And mature plants produce tall, frothy plumes of lacy white flowers, which attract pollinators such as bees and butterflies.
Beautiful and low maintenance with healthy, tasty stalks… Are you ready to add some rhubarb to your garden? Then let’s jump in to learn how to grow and care for these plants!
Here’s how the leaf unfurls:
What Is Rhubarb?
A hardy perennial, rhubarb belongs to the genus Rheum and is grown for its long, edible stalks (petioles) which have a bold, sharp taste.
Growing from rhizomes, the stalks range in color from light green to pink to deep scarlet and are topped by large, heart-shaped leaves with a crinkly texture and ruffled edges.
The leaves emerge as large buds in early spring and unfurl with a fascinating display – like pink-tinged, green plant brains!
Today’s culinary variety, R. x hybridum, is an open-pollination cross of the species previously used for their health or medicinal properties, R. rhabarbarum and R. rhaponticum.
Mature plants flower in early summer and feature beautiful, tall spires of frothy white flowers.
But don’t expect flowers until plants are a few years old, and note that heritage varieties are more likely to flower than newer hybrids.
Many gardeners remove the flower buds to concentrate energy into the leaves and stalks. But flowering doesn’t impact flavor or texture, and they add a lovely, astilbe-like charm to the garden beds.
Rhubarb crops well for several seasons and plants can live for up to 20 years, growing one to five feet tall and wide, depending on the variety and climate.
Hardy in USDA Zones 3 to 8, plants go dormant in fall and the rhizomes require a cold period of at least 500 hours in temperatures below 40°F for the proper formation of new buds.
Dormancy breaks when temperatures reach 40°F, and plants thrive in mild temperatures in the range of 60 to 75°F.
However, they do struggle once the mercury climbs over 80°F, and they won’t survive in consistent temperatures over 90°F. Provide shade in areas with hot afternoon sun.
Gardeners in warmer zones have luck growing rhubarb as a winter annual, discarding the rhizomes in spring as temperatures heat up.
Please note that the leaves are toxic and should not be eaten because they contain high levels of oxalic acid.
However, they are perfectly safe to go in the compost and do not have any detrimental impact on compost quality – oxalic acid is not readily absorbed by roots and degrades quickly when plant cells break down.
Cultivation and History
Native to the areas of southern Siberia and northwestern Mongolia, rhubarb has a long history in traditional Chinese medicine.
One of the earliest references to Rheum use can be traced back to 270 BCE in an ancient text known as “Shen Nong Ben Cao Jing,” or “Shen-Nong’s Herbal Classics,” a compilation of oral traditions about agriculture, herbs, and medicinal plants.
In the Greco-Roman cultures, it was used medicinally to combat many ailments – but importing it along Silk Road routes was expensive and it commanded a price similar to valuable spices like cinnamon, saffron, and pepper.
Planted as a medicinal in medieval European gardens, it wasn’t until the early 18th century that it was grown as a food plant.
And it didn’t become popular until the end of the century when European beet sugar became an affordable and available replacement for pricey, imported cane sugar.
Plants arrived in North America in the mid-1700s for their reputed healing properties but they weren’t used for culinary purposes here until the mid-1800s.
Botanically a vegetable, rhubarb is often referred to as a fruit because that’s how we use it culinarily.
Also known as pie plant, the stalks are most often cooked with sugar to counter the keen, biting flavor and made into savory dishes like chutney, ketchup, and salsa, or sweet ones like cakes, crumbles, ice cream, and naturally, pies.
Often combined with strawberries in baked goods, other flavorful blends include sliced apples, berries, currants, kiwi, and gooseberries.
The tangy stalks can also be eaten raw, but usually only by young children who don’t know better! (Shared memory, anyone?)
Seriously, the flavor of the raw stalks is highly acerbic and much enhanced with a touch of sugar or maple syrup.
Rhubarb also has a strong nutritional profile. It’s rich in antioxidants such as anthocyanins and vitamin K, and contains beneficial amounts of vitamin C, calcium, and fiber.
Propagation
Rhubarb can be propagated from seed, but crown division is the easiest, fastest, and most reliable method for new plants.
From Seed
In early spring about eight weeks before the final frost, fill individual four-inch pots with a good potting or seed-starting soil mix.
For southern gardens, sow seeds in late summer.
Place two seeds into each pot, sowing them one-half to one inch deep.
Water lightly to moisten the soil and keep at room temperature (60 to 75°F). After sprouting in five to 10 days, move to a bright window or place under a grow light.
When seedlings are three or four inches tall, move them outdoors to a slightly shady location to harden off for seven to 10 days, increasing the time spent outdoors by about an hour each day.
Keep the soil moist, but not soggy.
After hardening off, plant out into a sunny spot with fertile, well-draining soil.
Potted seedlings should be transplanted at the same depth at which they are growing in their pots.
Depending on the variety, space plants one to three feet apart to accommodate their spread.
To reduce the risk of transplant shock, plant out on a cool, cloudy day – hot sunshine on the large leaves can cause plants to droop.
For more seedling details, check out our guide on how to start rhubarb from seed.
From Divisions
Division is the best way to rejuvenate old plants and it’s the easiest, fastest, and most reliable way to propagate new ones.
In early spring before new shoots emerge, or in autumn as plants enter dormancy, dig out the entire root ball. Fully insert a spade all the way around the roots, about six inches out from the crown, and lift out.
Use a clean, sharp garden knife to divide the root ball into equal sections, ensuring each piece has one to three eyes (buds) and a healthy section of rhizome – the more buds each section has, the bigger the plant will ultimately grow to be.
Very old plants can develop hard, woody rhizomes and you might need a garden saw or hatchet to sever them.
For the healthiest divisions, replant promptly, following the steps outlined below.
Transplanting
Divisions and nursery crown stock can be planted in early spring as soon as the soil can be worked, or in autumn when plants are dormant.
Prepare the planting site by loosening the soil to a depth of 12 inches.
If your soil is clay-based or dense, create a four- to six-inch raised mound to improve drainage and prevent root rot.
Mix in some organic material such as compost or well-rotted manure.
To improve drainage, add some grit, such as landscape sand, pea gravel, perlite, or stone chips.
To help maintain moisture in the root zone, you can add moisture-retentive materials such as coconut coir, peat moss, or vermiculite.
Stir in one or two tablespoons of bone meal for strong, healthy roots.
Plant divisions or nursery stock about six inches deep with the crown one to two inches below the soil and space plants one to three feet apart.
Backfill and firm the soil gently but avoid tamping down the crown area.
How to Grow
Heavy feeders, rhubarb likes deeply cultivated, well-draining, and fertile, loamy soil that’s rich in organic matter. They also need full sun and do best in slightly acidic soil with a pH of 5.5 to 6.5.
Provide up to two inches of water per week, keeping the soil lightly moist but not wet.
Rhubarb can also be grown in containers, but you’ll need one that’s fairly large. And container plants need to be divided more frequently, usually every three years.
As a companion plant, rhubarb benefits brassicas such as cabbage, kale, and cauliflower with their ability to deter whiteflies.
They also protect beans by repelling aphids and in return, enjoy the extra nitrogen beans leave in the soil.
Growing Tips
Rhubarb is easily cultivated and the following tips ensure vibrant, healthy plants with plenty of tartly tasty stalks.
- Grow in full sun and provide protection from hot afternoon sun if needed.
- Rheum does not do well in waterlogged conditions. Ensure your soil is well draining or plant in mounds to keep the roots healthy.
- Provide one to two inches of water per week.
Maintenance
Apply a thick, four- to six-inch layer of compost over the root zone in spring.
In early summer, apply a four-inch layer of bark mulch, leaf mold, or straw to keep roots cool and help retain moisture, but keep it a few inches away from the crown.
Fertilize plants in early spring with an application of slow-release pellets scratched into the root zone and reapply in midsummer.
Keep the pellets away from the crown to avoid burning and use a balanced formula such as 10-10-10 NPK.
After the growing season ends, cut back foliage to the ground and clean beds of decaying vegetative matter and debris.
To protect the root stock from freeze/thaw cycles, in autumn remove old summer mulches and apply a six-inch protective mulch over the root zone and crown.
Use mulch materials such as compost, pine boughs, or straw. Remove winter mulches in early spring.
Dig up and divide the roots every five years or so when plants are dormant – the steps for doing this are outlined in the Propagation section above.
Cultivars to Select
With close to 100 cultivars available, there are plenty to choose from. Here are some favorites to get you started:
Chipman’s Canada Red
With an exceptionally sweet flavor and crisp texture, the deep red stalks of ‘Chipman’s Canada Red’ are a favorite for baked goods, compotes, and preserves that require less sugar.
‘Chipman’s Canada Red’
High yielding, they quickly form large clumps of thick stalks with a mature size of two to three feet – and their fast growth makes them a good choice to grow as a winter annual in warm areas.
Hardy in Zones 3 to 8.
Container plants are available at Nature Hills Nursery.
Crimson Red
Popular for compotes, jams, and pies, ‘Crimson Red’ produces plump, ruby red stalks with a sweetly tart flavor.
‘Crimson Red’
This non-stringy variety grows 24 to 48 inches and has plenty of ornamental merit with beautiful green leaves and bold spikes of creamy white flowers in early summer.
Hardy in USDA Zones 3 to 8.
Extra-large ‘Crimson Red’ roots are available from Burpee.
Hardy Tarty
With outstanding heat tolerance, Hardy Tarty™, aka ‘Colorado Red,’ makes a good choice for northern or southern gardens, with thick stalks that are tartly tasty for baking, jams, and preserves.
Hardy Tarty
The fast-growing, bright red stalks grow on compact plants that reach 24 to 30 inches and rarely bolt to seed. Hardy in Zones 3 to 8.
Bare root stock is available at Walmart.
Victoria
Excellent for cooking, with a sweet, mild flavor, ‘Victoria’ features plump, thick stems with crimson-tinged or bright red skin and a non-stringy texture that’s ideal for crumbles, pies, and preserves.
A steady producer, flower stalks can reach up to six feet tall with small cream to pink flowers in midsummer. Hardy in Zones 3 to 8.
‘Victoria’
If you’d like to try your hand at cultivating some heirloom seeds, you can find ‘Victoria’ seed packets available via True Leaf Market.
And live plants or rootstock can be purchased at Burpee.
Managing Pests and Disease
Rheum species and cultivars are fairly free of pests and diseases, though there are a few to keep an eye out for.
Like the rhubarb curculio (Lixus concavus). This half-inch-long beetle is dark colored, with a long snout that curves downwards.
They should be handpicked from plants when spotted. Or sprinkle diatomaceous earth around your garden beds to repel them.
Bonide Neem Oil
If you see evidence of spider mites, such as stippling of the leaves, treat them with neem oil, such as this one from Bonide in pint, quart, and gallon sizes that’s available via Arbico Organics.
Fungal leaf rot can happen if the foliage remains wet for too long, or if plants are too crowded with poor air circulation. Most often, only the leaves are impacted, not the stalks.
Harvest stalks with impacted leaves first, and carefully remove and dispose of the leaves (not in the compost) so as not to spread the fungus. Water at the base of plants to avoid wetting the leaves.
Phytophthora crown rot can occur if the plants’ subterranean parts sit in too much water for too long.
To avoid crown rot, be sure to plant in well-draining soil or plant in hills to improve drainage.
Harvesting
With divisions or newly planted nursery stock, wait until the second or third year of growth to harvest.
This is to develop strong, healthy roots for vibrant, large plants with plenty of juicy stems.
And to do that, the leaves are needed to convert the sun’s energy into food – no leaves, and the roots stay small. So it’s best to be patient… it does pay off!
Early varieties can be harvested starting in March and April with maincrop varieties ready in April and May – both types are harvested throughout the summer.
Choose stalks that are at least 10 inches long, picking a few stalks per plant. To avoid stressing plants, take care not to harvest all the stalks from a given plant at once.
For perennial clumps, let some leaves remain in place over summer to generate energy for next year’s growth.
For annuals, harvest all the stalks when temperatures rise and stay above 75°F. Dispose of crowns in the compost pile after your last harvest.
To harvest, grab a stalk at the base then pull down and twist sideways – it should break off easily. You can also cut the stalks with a clean, sharp knife.
Immediately cut off the leaves and put them in the compost bin – unless they are diseased. In that case, seal them in a bag and dispose of them.
Cut stalks can be stored in the refrigerator for up to two weeks. Wrap them in plastic or stand them up in a container of water, much as you would fresh herbs, to keep them hydrated.
Preserving
Rhubarb’s fantastic flavor can be enjoyed in preserves as well.
To freeze, cut clean, dry stalks into one-inch pieces and place in a single layer on a baking tray.
Freeze pieces until firm, about two hours, then pack into resealable containers and freeze for up to one year.
To dry, cut the stems into quarter-inch slices and spread in a single layer on dehydrator trays.
Dehydrate on the lowest setting until the texture is crisp. Store in an airtight container in a cool, dry cupboard.
Canning in a hot water bath is another way to preserve the sassy stalks in delectable compotes, conserves, jams, and stewed fruit.
Recipes and Cooking Ideas
When dreaming about this fruity veg in the kitchen, an absolute must is the classic strawberry rhubarb pie featured on our sister site, Foodal.
Sweet and sour, it has an old-fashioned flavor that deserves a place on the modern table.
Also from Foodal comes a mouthwatering rhubarb buttermilk sherbet, featuring its unmistakable tart taste.
For even more rhubarb recipes, check out all that is available over on Foodal.
And don’t forget the humble but beloved crumble that Mum or Gran used to make. With or without strawberries, it’s always scrumptious!
Quick Reference Growing Guide
| Plant Type: | Perennial herbaceous vegetable | Maintenance: | Low |
| Native to: | Mongolia, Siberia | Tolerance: | Deer, rabbits |
| Hardiness (USDA Zones): | 3-8 | Water Needs: | Moderate |
| Bloom Time: | Spring, summer | Soil Type: | Fertile, loam |
| Exposure: | Full sun | Soil pH: | 5.5-6.5 |
| Time to Maturity: | 2-3 years (divisions and crown stock) | Soil Drainage: | Well-draining |
| Spacing: | 1-3 feet, depending on cultivar | Attracts: | Bees, butterflies |
| Planting Depth: | 4-6 inches with crown 1-2 inches below the soil (bare roots); 1/2 inch (seeds) | Companion Planting: | Beans, brassicas |
| Height: | 1-4 feet | Family: | Polygonaceae |
| Spread: | 1-3 feet | Genus: | Rheum |
| Common Pests and Disease: | Rhubarb curculio, mites; fungal leaf rot, crown rot | Species: | x hybridum, rhabarbarum, rhaponticum |
Savories and Sweets
With its delicious tart flavor, rhubarb is a favorite for both savory dishes and sweet ones.
Ensure your plants receive enough water, fertilize regularly, and divide every five years or so to keep them vibrant and healthy.
You’ll have plenty of stalks for making crumbles, compotes, or pies, and still have enough to share with the neighbors!
How do you folks use your harvest? Let us know in the comments section below.
And for more cultivation ideas, be sure to read these rhubarb guides next:
