9 Tips for Growing Delicious Rhubarb in Pots and Containers
Tender, crunchy stalks sprout from rhubarb crowns. The red or green stalks are edible in pies, sautés, and desserts. If you lack in-ground space, consider growing this veggie in containers; it’ll thrive with extra care! Seasoned grower Jerad Bryant shares nine expert tips to help.
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Perennial vegetables aren’t just for homesteaders and gardeners with acres of space. You can cultivate gorgeous, delicious rhubarb on your porch in a pot! It takes well to container culture so long as it has good soil, regular moisture, and plenty of sunlight.
Whereas in-ground specimens thrive with few inputs, potted specimens benefit from extra care during the growing season. Watch them closely in early spring and summer to ensure they get what they need. Thriving plants will produce dozens of leafy stalks with giant, green leaves and thick, red stems. The stems are edible, while the leaves and roots are not.
If your plant struggles in a container, use these tips as a checklist. Go over each one to ensure your plant has what it needs to survive and thrive. When you grant your rhubarb what it needs, it’ll reward you with bushels of edible stalks for recipes!
Use Large Containers
Rhubarb plants have large, extensive root systems. Like many other perennials, they grow larger, wider, and deeper each year during the growing season. Grant them a pot that suits their size to give them a good start in your garden.
There are two main ways to source rhubarb: crowns and seeds. Crowns are soilless rhizomes that you plant in the fall or early spring, while seeds sprout anytime during the growing season. Seedlings will grow well in small pots while they’re young, whereas crowns need pots with plenty of width and depth for their rhizomes to spread.
Instead of containers, raised beds and planters work well too. You can have an entire plot dedicated to the veggie. You may also partition a portion for rhubarb and have other annuals and perennials fit in the spaces between the plants. Rhubarb grows well with columbine flowers—it prevents spider mites from feeding on the wildflowers.
Choose a Bright Location
Rhubarb plants need full sun to thrive; they benefit from growing under six to eight hours of daily direct sunlight. Any fewer hours, and they’ll have weak growth with thin stems. Provide plenty of direct sunlight for the best-tasting, most lush plants.
Unlike peppers and tomatoes, this crop may suffer if it receives too much direct sunlight. Southern states with long, hot summers and desert regions with excessive light levels are difficult environments for growing rhubarb.
You can tell if your specimen is receiving enough sunlight based on its growth. If there are ample, thick shoots with large, fan-like leaves, the plant is well-lit. If there are few leaves and they’re small or leggy, consider moving the container towards a sunnier location.
Water Regularly
Consistent moisture is necessary for healthy rhubarb growth. These perennials love water, and they appreciate a steady source during the growing season. After establishing themselves in your garden, the plants are drought-tolerant for short periods.
Though rhubarb is drought-tolerant, it grows best with consistent moisture. You want to ensure the soil is moist, not soggy, and well-draining. This is especially important for potted plants. They dry out quickly without the moisture-conserving protections of in-ground specimens.
To conserve water, consider mulching the top of the soil with compost or a similar organic amendment. The layer of mulch preserves moisture underneath, keeping plant roots cool, moist, and well-fed. Straw, leaf mold, and fallen leaves also work well as mulch.
Grow in Good Soil
Good soil and water retention go hand-in-hand! A well-draining, fertile, and loamy mix is best for growing rhubarb. Soil type is especially important for potted plants. The mix degrades and compacts over time, which is why drainage particles are necessary for good potting soil.
Ensure your mix has pumice, perlite, or vermiculite. These particles add drainage, structure, and porosity to the soil. They allow roots to breathe underground despite wet conditions. Organic matter is also important; most soil mixes will have composted fir bark, coco coir, peat moss, or a similar organic material.
Loam is a perfect combination of silt, clay, and sand. A sandy loam is best for this crop, though the plant can tolerate slight variations like sandy clay loam or loamy sand. Drainage and fertility are the most important aspects—the rhizomes struggle if they sit in standing water.
pH levels are another factor to consider when growing this perennial in pots. Ensure the pH stays between 6.0 and 6.8 for optimal growth. Rhubarb appreciates slightly acidic conditions, which is why it thrives in the acidic soils of the Pacific Northwest.
Fertilize as Needed
Fertile soil is nutrient-rich; it contains dozens of primary and secondary nutrients, as well as micronutrients. Nitrogen, phosphorus, potassium, sulfur, calcium, and magnesium are all important elements for healthy rhubarb.
Compost is a superb soil amendment, as it leaches nutrients into the ground while also improving drainage, water retention, and porosity. Rhubarb thrives with an annual or biannual compost addition for these reasons. The stems grow well with the extra nutrients, while the roots thrive with access to all the water and air they need.
Though compost is all you need to maintain a healthy crop, some extra fertilizer can boost production. In spring, add an organic fertilizer with equal amounts of nitrogen, phosphorus, and potassium. A well-balanced fertilizer boosts stem production for incredible harvests.
Keep Rhubarb Cool
Though this vegetable appreciates full sun, it needs relatively cool temperatures to perform well. Cool, mild weather leads to blood-red and bright pink stems that are full of flavor. Summer temperatures below 75°F (24°C) lead to the biggest, boldest rhubarb leaves.
If temperatures rise above the optimal range, consider giving your specimen afternoon shade during the hottest hours of the day. This will help it thrive despite heat waves and dry conditions. Ensure the soil stays moist, but not soggy, throughout the sunny period to help it survive.
Because potted specimens are easily movable, you can move your rhubarb to keep it cool. Consider moving your plant to the shade under a patio, porch, or balcony on especially hot summer days.
Provide Cold Winter Temperatures
Like asparagus, perennial rhubarb is frost-hardy! Not only does it survive frosts, but it needs them to grow well in the spring. Grant your plant 500 or more hours of winter temperatures under 40°F (4°C). This winter chill period helps the rhizomes form leafy shoots in spring.
Though this crop is frost-hardy, it can suffer when temperatures fall too low. Avoid extremely frosty weather below 28°F (-2°C). If temperatures fall below this point, consider mulching the rhizomes with thick layers of mulch in the fall. After the plant enters dormancy, add a layer two to three inches thick over the container’s soil.
Some varieties are more cold-hardy than others. Consider using an especially frost-hardy cultivar if you garden in USDA hardiness zones 1 through 6.
Divide Mature Clumps
Potted plants outgrow their containers after a few years of healthy growth. You’ll need to split them up and uppot the small rhizomes in new pots. The best times to divide are in early spring or fall when the weather is cool, moist, and mild.
To divide, unpot your plant and shake it free of soil. You’ll see a large, thick, and rhizomatous structure that can be heavy! Take a good look at it, and use a sharp knife or spade to split it into several portions. Ensure each piece has a few knobby structures so that healthy roots and shoots will sprout from it.
After dividing, plant the new pieces in pots with well-draining soil. Keep them moist while they establish, and protect them from harsh frosts their first winter. They’ll be drought and frost-tolerant after establishing themselves in their second year.
Watch for Pests
Pests and diseases are the last things you’ll want to watch for; though unlikely, they can be devastating! Rhubarb curculios, stem borers, slugs, and snails are common pests, while leaf spot and red leaf are two common diseases.
To prevent these pests and pathogens, ensure your rhubarb is happy, healthy, and vigorous. The happier the plant is, the more likely it’ll resist external pressures. Avoid overharvesting to ensure the specimen has enough energy to survive attacks.
Protect rhubarb from pests in spring with a floating row cover. For disease prevention, plant each perennial three to four feet away from each other so they have proper air circulation. Avoid soggy soil, and amend poor sites with compost to bolster the plants’ defenses.
