How and When to Harvest Rhubarb – Expert Guide to a Tart & Tasty Harvest

Nothing says spring like strawberry rhubarb pie! But before you can bake your very own homegrown dessert, you have to learn how and when to harvest rhubarb for peak flavor and freshness. For many beginners, the harvest window can feel a bit mysterious. The stakes feel high because harvesting at the wrong time or in the wrong way doesn't just result in a stringy pie, but can deplete the plant's energy reserves for the following year. Don't worry, though – once you know the tell-tale signs of a ready stalk, you’ll be picking with confidence.

Growing rhubarb in the garden rewards you with years of delicious spring harvests and a beautiful ornamental plant that has a similar effect to a hosta. Rhubarb, a member of the buckwheat family, is a perennial with large leaves borne off of stalks that range from red to green. It is often called the pie plant, and for good reason! These hardy perennials can produce for 10 to 15 years if harvested correctly, making them one of the most generous plants in your edible landscape.

These stalks, or petioles, are the edible portion of the plant and are what gardeners harvest to use in pies, sauces, and jams. Rhubarb is one of the prettiest edible plants and it looks right at home in the vegetable garden or the perennial border. As the weather warms, you'll see the crinkled leaves begin to unfurl from the crown. A great sign that harvest is approaching is when the leaves have fully expanded and the stalks have reached their characteristic thickness, usually about the diameter of a finger.

Despite the popularity of rhubarb in the garden and its deliciously tart stalks in spring desserts, the large leaves of this plant are poisonous. That’s why learning how to harvest rhubarb the right way is important not only for taste, but also for safety. Harvesting rhubarb the wrong way can also harm the plant. It’s vital to use the correct technique and never pick more than the plant can stand to lose. So, is your rhubarb ready for action? Let’s dig into how to harvest rhubarb the right way.

What to Know Before You Harvest

Rhubarb (Rheum rhabarbarum) is most often grown for its leaf stalks. Originally cultivated as a medicinal plant in China and Russia over 2000 years ago, its most common use shifted to cooking in Great Britain and the United States around the 18th century. Benjamin Franklin is often credited with introducing rhubarb to North America, recognizing its value as a hardy crop and a culinary delight.

The underground portion of the plant is made up of rhizomes which survive winter underground. In fact, a cold period near freezing is a necessary part of caring for rhubarb over winter and required for the plant to break dormancy. Most rhubarb varieties require at least 500 hours of temperatures below 40°F (4°C) to produce high-quality stalks the following season. This is why rhubarb thrives so beautifully in USDA zones 3-8 but can struggle in the deep South.

Come spring, buds form off the crown of the plant, unfurling stalks and leaves that can reach a height of 2.5-3 feet (76-91 cm) and nearly the same width across. Before harvesting rhubarb, take a moment to spot your plant's health. Look for vibrant color and firm stalks. If you notice any mushiness at the base of the stalks early in the season, this could be a sign of crown rot, often caused by poor drainage. A healthy plant should feel sturdy and resilient to the touch.

While the exotic leaves look wonderful in the garden, do not eat them. Rhubarb leaves are high in oxalic acid and soluble salts which are toxic to humans. That said, rhubarb is nutrient-rich. It contains vitamins A and C, dietary fiber, thiamin, niacin, riboflavin, phosphorus, and potassium. Even though you can't eat the leaves, they make a fantastic addition to your compost pile; the oxalic acid breaks down during the composting process, leaving you with rich, safe soil for next year.

Rhubarb loves slightly acidic soil (pH 6.0 to 6.8). Grab a soil meter, like the Sonkir Soil pH & Moisture Meter from Amazon, to check soil is in the best zone for nutrient uptake and that roots aren't sitting in soggy soil.

When to Harvest Rhubarb

Technically rhubarb is ripe all spring and summer. But for the best flavor and the health of the plant, there are certain times that are better for harvesting rhubarb. Depending on where you live, rhubarb season will happen at slightly different times. Generally, rhubarb is ready to harvest in April or May. But in cooler northern climates, you might see the harvest extend into July.

The surest way to know when to harvest rhubarb is to look at the stalks. Depending on cultivar, your rhubarb stalks may be green or red at the time of harvest. So don’t let color be the signal for when to harvest rhubarb. Some heirloom varieties like 'Victoria' stay green even when ripe, while 'Crimson Red' will be deep ruby.

Instead, look at the size of your rhubarb stalks to tell if they are ready. When the stalks reach 10 inches (25cm) long, it is time to harvest. At this size, you can be sure your plant is established and can tolerate harvesting. If your rhubarb stalks are small and spindly, leave them to continue growing. Harvesting stalks that are too thin can stress a young plant.

When harvesting rhubarb, only take one-third of the plant. Taking more than this can harm your rhubarb and weaken or even kill it. Since rhubarb is a perennial, you want to treat it well so it continues to give you plentiful harvests for many years.

Knowing when to harvest rhubarb also means knowing when the season is over. Rhubarb season lasts for about 8-10 weeks, typically ending in June. Though you can keep harvesting rhubarb until fall, this will impede your rhubarb plant’s ability to store energy for the winter. Stop harvesting once the stalks become noticeably thinner. This is the plant's way of saying it needs to keep leaves and recharge.

If you recently planted your rhubarb, wait two years after planting to harvest. This will ensure the plant’s crown and root system is established and can tolerate harvesting. In your plant’s third year, you can harvest rhubarb for a month. In the following years, you can harvest rhubarb for 8-10 weeks.

If you are looking for an earlier, sweeter crop, some gardeners choose to force their rhubarb by covering the crowns in late winter to block out light.

How to Harvest Rhubarb

There are two different methods to harvest rhubarb. The first way is to use a sharp, clean knife like the Fiskars Harvesting Knife, available from Amazon, or garden shears like the Felco F6 Pruning Shears (also available from Amazon) to cut the stalk at the base of the plant. Be sure to cut at the base and not part way up the stalk as this creates an open wound where disease can enter and harm your plant. Since rhubarb is a perennial edible plant, it’s important to think beyond this year’s harvest and consider the long-term health of your plant.

The second rhubarb harvesting method is even easier than the first and it doesn’t require any tools. Grasp a rhubarb stalk at the base, then gently twist and pull to remove. This twist and pull method is often preferred because it naturally detaches the stalk from the socket, leaving no stump behind. Just be careful not to tug so hard that you lift the roots.

Cut off and compost rhubarb leaves after harvesting the stalks. If you have children or pets, do not leave rhubarb leaves in the garden or kitchen. Rhubarb leaves are poisonous, so discard them quickly to prevent humans or pets from accidentally ingesting them.

If rhubarb flowers appear, cut them off immediately. When rhubarb blooms, also known as bolting, this diverts all the plant’s energy away from producing edible stalks and instead channels it toward flowering and setting seed. Bolting is often triggered by a sudden spike in temperature or plant stress. By snipping the flower stalk at the base as soon as it appears, you signal to the plant to get back to growing delicious petioles.

How to Store Rhubarb

Wash or wipe down the stalks with clean water before storing your rhubarb harvest. You may store freshly cut rhubarb in a plastic bag in the fridge for two to four weeks. For maximum crispness, some experts suggest wrapping the stalks loosely in a damp paper towel before placing them in a perforated plastic bag in the crisper drawer.

Another easy and delicious option is to cook your harvest into rhubarb sauce, then refrigerate or freeze for later use. If you want to freeze it raw, chop the stalks into one-inch (2.5cm) pieces and spread them out on a baking sheet to flash-freeze before transferring them to a freezer bag. This prevents the pieces from clumping, allowing you to pour out exactly what you need for a mid-winter muffin craving.

To keep your rhubarb at its best, never store it with the leaves attached. The leaves will continue to draw moisture from the stalks, causing them to go limp and rubbery within hours. Trim them immediately in the garden to keep that crunch intact.

Rhubarb Care After Harvesting

Once the harvest season wraps up in late June, your rhubarb plant deserves a little appreciation for its hard work. This is the most critical time for ensuring a great crop for next year. To prevent plant exhaustion, ensure you leave at least one-third (ideally half) of the foliage on the plant throughout the summer. These remaining leaves help your rhubarb recharge the rhizomes for the following spring.

Giving the plant a deep, nourishing drink. Rhubarb is a thirsty plant, and a consistent supply of water during the hot July and August months is essential. Follow this with a generous application of well-rotted manure or high-quality compost around the base of the plant, being careful not to bury the central crown, which can lead to rot.

A 2-inch (5cm) layer of mulch is perfect for retaining moisture and suppressing weeds that might compete for nutrients. You can buy Natural Pine Bark Mulch Nuggets from Amazon for a tidy look while slowly breaking down to improve soil structure. That’s all there is to harvesting rhubarb. Now that you know when and how to harvest rhubarb, it’s time to start picking and eating these tasty spring stalks.

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