Rhubarb is easy to grow, and an excellent choice for beginners and experts alike. Especially if you want a low-maintenance option for your vegetable garden.
This hardy perennial is a staple for many long-time gardeners. But, to be successful, you must first understand how to care for it correctly.
In this guide, I’ll tell you everything you need to know about growing your own rhubarb, no matter what your skill level. You’ll find all of the essential information about soil, water, fertilizer, sun, temperature, pest control, and much more.
Quick Rhubarb Plant Care Overview
| Scientific name: | Rheum rhabarbarum |
| Classification: | Vegetable |
| Common names: | Rhubarb |
| Hardiness: | Zones 3-8 |
| Temperature: | 40-75°F (4.4-23.9°C) |
| Flowers: | White or pink, blooms summer-fall |
| Light: | Full sun to part shade |
| Water: | Keep soil evenly moist, do not overwater |
| Humidity: | Average |
| Fertilizer: | General purpose plant food spring-summer |
| Soil: | Well-drained, loamy, fertile |
| Common pests: | Rhubarb curculio |
Information About Rhubarb
Rhubarb (Rheum rhabarbarum) is a perennial vegetable native to Asia that’s been cultivated worldwide for hundreds of years.
It has long stalks, or ribs, with large green leaves at the top. A mature plant can be 4’ wide or larger and have stalks that are red, pink, or green.
The leaves contain oxalic acid, which makes them toxic and inedible (source). But gardeners love the stalks for their sour, tart flavor. They’re popular in baking, preserves, desserts, and sauces.
These low-maintenance plants rarely has pest or disease problems, and they can continue to produce for 8-15 years.
Different Types
There are many varieties of rhubarb with differences in hardiness, stem color, size, and growth rate. But thankfully, all of them can be cared for in the same way. Here are a few of the most popular types:
- Canada Red – This plant has shorter stalks that are red inside and out, and more tender than other varieties.
- Riverside Giant – This slow-growing, cold-hardy variety produces long green stems.
- Macdonald – The long, tender pink stalks on this variety are juicy and less tart, making it a popular option.
- Victoria – This is one of the most favored cultivars due to the slight sweetness and tender stalks, which have red exteriors and green interiors.
Hardiness
Rhubarb is a very cold hardy perennial that will come back every year in zones 3-8. Temperatures as low as -20°F (-28°C) won’t damage it.
In fact, it needs the cold to produce new stalks every year. You’ll have a hard time growing rhubarb if it doesn’t get below freezing where you live.
How Does Rhubarb Grow?
The edible fibrous stalks grow from buds that form around the crown or rootball. Each year, clusters of new buds develop on the outside of the previous year’s, gradually causing the plant to become wider.
Large, broad green leaves grow from the top of each stalk. On mature plants, tiny clusters of flowers can develop on tall spikes in the spring.
As it warms up in the summer, the stalks will get thinner and shorter as the plant focuses on storing energy for next year’s bounty.
Related Post: How To Make Rhubarb Jam: Easy Recipe
Where To Grow Rhubarb
In the cooler zones of 3-5, choose a full sun location to encourage the quickest growth. In the warmer zones of 6-8, find a spot that gets partial shade in the afternoon to protect it from the hot sun.
For best results, the bed should have has rich, fertile, and well-draining soil. An area that stays consistently moist, but not overly wet, would be perfect.
When To Plant
Plant your Rheum rhabarbarum as soon as the ground is workable in the early spring. You can start it from seed, but it will take several years to reach full maturity.
Dig deep holes and fill them with compost or a well-rotted manure. Add a slow-release fertilizer, then plant the crown 1-2” under the soil.
A single rhubarb plant will grow wider over the years, so make sure to space them 3-4’ apart so they have plenty of room, and don’t become overcrowded.
Rhubarb Plant Care & Growing Instructions
Now that you have the right location in mind, it’s time to talk about how to care for rhubarb your plant. My tips below will help make it an easy addition to your garden.
Sunlight
Rhubarb needs 6-8 hours of sunlight to produce healthy stalks, and to ensure the crown has enough energy stores to grow back every year.
Choose a full-sun location, unless you live in a warm climate (zones 6-8). In that case, provide shade in the afternoon during the hottest part of the day to prevent sunburn.
Water
While it can handle short periods of drought, rhubarb grows best with consistent moisture, and it doesn’t like to dry out for too long. Water deeply when the top 1” of soil is dry.
Give it a deep soaking, but never to the point where the water pools or the ground is soggy, because too much can lead to crown rot.
Mulch around the base of the plant to help retain moisture, especially in the summer when temperatures rise. Compost, hay, or shredded bark will work great for that. Stop watering in the fall when the foliage dies off as the plant enters its dormant period.
Related Post: How To Can Rhubarb At Home
Temperature
These cold hardy plants do not like the heat, and will grow the most in the spring and early summer when it’s between 40-75°F (4.4-23.9°C). Anything hotter can cause drought stress, wilting, bolting, or scorching.
Cooler temperatures will trigger the plant to go dormant in the fall and winter. But that’s a good thing, because it needs a rest period below 40°F (4.4°C) to produce new stalks the following spring.
Fertilizer
Rhubarb is a heavy feeder and will benefit from regular applications of a balanced general-purpose vegetable fertilizer from spring through summer.
Use an all-purpose liquid twice a month spring through early summer, or top-dress with slow-release granules before it breaks dormancy in the spring.
In early spring, top-dress with compost or well-rotted manure, then work slow-release granules into the soil monthly. Or apply a liquid like compost tea or fish emulsion every two weeks.
Soil
One of the things that makes rhubarb so easy to care for is that it can grow in almost any type of soil, as long as it’s well-draining. But the ideal mix is rich, fertile, porous, and loamy
It should also be slightly acidic, or between 6-6.8 on a ph probe. If your soil is alkaline, you can amend it with a slow-release acidifier.
You can improve poor-quality garden soil by digging a deep hole before planting, and adding compost or well-rotted manure, as well as slow-release fertilizer granules into it. Or you can top-dress your plants.
Pruning
You don’t need to worry about pruning your rhubarb, it will grow just fine without it. But regular trimming can help maintain the appearance and control the size of the plant.
Remove dead or damaged stems by simply twisting or cutting them off. Use sharp pruning shears to snip away the flower stalks as they appear, to allow the plant to divert the energy back into the crown to store for next year.
Propagation
If your rhubarb is older than five years, you can remove new clusters or divide the crown in the late winter or early spring, while the plant is still dormant.
Use a sharp, sterile garden knife to split them, and make sure each section contains at least one bud. Share them with friends, or replant them with plenty of space to grow.
Pest Control Tips
Though they are usually pest-free plants, the rhubarb curculio beetle enjoys feeding and laying eggs on the stems.
These pesky bugs overwinter in plant debris and dead leaves, so make sure to clean up your garden in the fall to help prevent them.
Holes and oozing sap in the stalks are signs of an infestation. Hand-pick the insects off the plant and drop them into a bucket of soapy water to get rid of them.
Disease Control Tips
Crown rot is a common problem in heavy, poor-draining soils, and is usually caused by overwatering. The main symptoms are wilting, yellowing leaves, and soft stems.
Leaf spot is a fungus that can spread from water or wind. It causes red, yellow, or brown circular lesions on the leaves. Keep the ground clear of old plant debris and water at the base to prevent splashing on the leaves.
If you notice spots on any of the foliage, remove and destroy the infected ones immediately to keep the disease from spreading.
Tips For Harvesting Rhubarb
You can begin lightly harvesting your rhubarb in the second year of growth by removing just a few of the larger outer stalks.
By the third year, you can remove up to ⅓ of the plant with each harvest as soon as the stalks reach 12-18” tall.
The best way to pick it is by holding a stem firmly in your hand and twisting it from the base. Remove the leaves immediately and discard them. They’re inedible and will make the stalks soft if you leave them on for too long.
Related Post: How To Freeze Rhubarb (With Or Without Blanching)
Troubleshooting Common Problems
Rhubarb is low-maintenance and rarely has issues, but no plant is problem-free. If you encounter one of these more common issues, my tips will get you back on track.
Thin, Spindly Stalks
Lack of light, nutrients, or age can all cause thin stalks. If your rhubarb plant is in full sun, try fertilizing it with add an all-purpose liquid or slow release granules.
If sun and nutrients aren’t the issue, and your plant is between 5-10 years old, it may be time to divide it. You can rejuvenate it by cutting the crown into sections, or by removing and transplanting the new bud clusters.
Brown Spots On Leaves
Leaf spot, a fungal disease, is often the cause of brown spotting on rhubarb leaves. It can come from moisture sitting on the foliage, poor airflow, or old plant debris.
The best approach is to remove any affected leaves and destroy them. Keep the plant’s base clean, avoid overhead watering, and make sure your plants are not overcrowded.
FAQs
Rhubarb grows quickly, but is not harvestable until the 2nd or 3rd year, depending on the specific variety you have.
Rhubarb does not spread by producing offshoots or runners, but each year the plant will grow wider as new buds develop around the outside of the crown.
Yes, rhubarb is easy to grow because it tolerates a wide range of soils, is pest and disease-resistant, cold-hardy, and it requires very little attention.
Rhubarb is a vegetable. People often mistake it for a fruit because it is frequently used in sweet recipes, like jams, jellies, and desserts to offset the sour flavor.
Rhubarb is a hardy perennial plant that will return yearly in zones 3-8. It doesn’t do well in warmer climates because it needs a cold winter to produce lots of thick, edible stalks.
Yes, rhubarb plants will come back every year in growing zones 3-8.
If you’d like to learn how to make the most of your space and get as much homegrown food as possible, then my Vertical Vegetables book is perfect! It will teach you all you need to know, has tons of gorgeous photos, and includes 23 DIY projects you can build for your own garden. Order your copy today!
Learn more about my Vertical Vegetables book here.
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Amy Andrychowicz
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