Part 3 in our Growing Rhubarb: A Guide for All Climates Series
A short series offering guidance on rhubarb, tips to grow it, and methods to grow it outside of its preferred range.
Once rhubarb is established, it requires surprisingly little maintenance, though a few simple techniques can greatly improve both yield and flavor. In part 3 of this series, we’ll cover how to care for rhubarb, including how to divide it, how to harvest it, and a couple of other tips.
In temperate climates, rhubarb generally survives the winter on its own. In fact, the plant needs around 500 hours (around 7 weeks) at 40°F (4 °C) or below to trigger healthy new growth in spring.
In the fall, allow the remaining leaves to die back naturally before cutting the stems near the base of the plant. The leaves can be added to your compost pile, but should not be left to break down around the plant.
While rhubarb is hardy down to -30°F (-34°C), extra protection can help in regions with particularly long or harsh winters, such as USDA Zone 4 or mountainous areas. Applying a thick layer of mulch after the leaves have been removed provides insulation against freezing temperatures. During my time in Idaho, I found that covering rhubarb with a pot throughout the winter helped temper the colder nights and protected tender shoots from late frosts, snow, and ground upheaval.
In warm desert climates, overwintering is more challenging. Unless winter temperatures regularly drop below 40°F, rhubarb crowns may struggle to survive. In the U.S., this includes the high desert regions of California and much of Arizona. Planting rhubarb in pots that can be moved to cooler locations, such as a garage or shed, can help the plant survive.
Young rhubarb plants—those less than two years old—require careful watering during dry spells to establish deep, vigorous roots. Once established, care mainly involves removing flower stems to encourage more leaf growth, clearing away faded leaves, and dividing overcrowded clumps.
Rhubarb should be watered when the soil around it becomes dry or the leaves show signs of stress. These hardy plants like to be kept damp, but not wet. If the summer is particularly hot and dry, growth will slow down, and the plant may enter a dormant state for the rest of the season.
Spring mulching is highly beneficial. You should apply a 2½-inch deep ring of organic mulch around each plant each year, extending roughly a foot wide. This helps retain soil moisture, suppress weeds, and maintain a stable, fertile soil environment.
Rhubarb occasionally produces flowering stems in spring or summer. Removing them promptly prevents the plant from weakening and reduces the chance of bolting. Flowering is more likely after wet summers, excessive nitrogen feeding, or in older plants that haven’t been divided for several years.
Dividing rhubarb is a satisfying way to rejuvenate plants and provide extra crowns to share. This is usually done after five years, though overcrowded or slow-growing plants may benefit from earlier division.
The best time to divide rhubarb is when the plant is dormant, typically between mid-autumn and early spring. Dig up the entire crown carefully, then split it into sections using a sharp knife or hori-hori.
Each division should include plenty of roots, a portion of the rhizome, and at least one bud. Outer sections are generally healthier than older inner sections, while weak or diseased pieces should be discarded. Replant the divisions the same day if possible, spacing them about three feet apart.
Rhubarb should not be harvested in its first year so that it can establish a strong root system. Light harvesting can be done in the second year, but full production really begins in the third year. From this point, up to one-third of the stalks can be removed at a time, typically from April or May, for around 10-14 weeks. Always leave enough leaves on the plant so it can photosynthesize and maintain healthy growth.
Select stems that are about a foot long with freshly unfurled leaves. To harvest, grip the base with your thumb on the skyward side and fingers beneath, then gently pull the stalk from the ground. Avoid cutting or snapping stems, which can damage the crown or introduce rot.
Harvested rhubarb keeps in the refrigerator for up to two weeks, or it can be frozen after being chopped into small pieces. Remember, only the stalks are edible—leaves contain oxalic acid and should be composted or discarded safely.
Rhubarb stems naturally grow towards the light, a bit like sunflowers. Being a very vigorous plant, this adaptation can be maximized by growing the rhubarb in near darkness.
To force rhubarb, you will need a crown that has been in your garden for at least 1-2 years, and is healthy and well-established. As the heavy winter frosts begin to ease, cover the crown to exclude light, which encourages tender, sweet stems.
Forced rhubarb is generally sweeter and juicier than normal rhubarb.
There are three main steps:
After 5–8 weeks, you should have fresh, tender stems about 1 ft long. Harvest gently, then uncover the plant once the risk of frost has passed. Lightly mulch again and allow it to rest for the remainder of the year—don’t harvest forced plants again until the next season.
Planting your rhubarb at the right time, caring for it through the seasons, and then dividing it when it gets mature will give you plants that can last over 15 years. One final tip from us is to stagger your plantings. Having plants of different ages means you will always have rhubarb ready to harvest, while some are resting after being divided or forced, or are freshly planted.
Happy growing, and happy eating!