Rhubarb is a unique vegetable whose sweet red stalks are often used in desserts. The best time to pick it is between early spring and early summer. But what about picking rhubarb in late summer or early August? Is that a good idea?
In this article, we’ll cover everything you need to know about harvesting rhubarb, including whether August harvesting is possible and how to get the best flavor.
Overview of Rhubarb
First, let’s go over some rhubarb basics.
Rhubarb isn’t really a vegetable, but it’s often eaten that way. It’s a perennial plant that dies back each winter and then grows back big leaves and red stalks every spring.
The stalks start off green but turn red as they mature. The leaves contain oxalic acid and are poisonous, so always remove them before eating the stalks.
There are two main types:
- Forced rhubarb – Grown early under cover, has sweeter, more tender stalks.
- Main crop – Grown fully outdoors, more tart flavor.
Traditional Rhubarb Harvesting Season
The best time to harvest main crop rhubarb is from early spring to early summer. Exact timing depends on climate and variety.
General guidelines are:
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Don’t harvest newly planted rhubarb at all the first year. Prevents weakening.
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Start harvesting established plants in spring once stalks reach adequate size, usually April or May.
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Peak harvest is mid spring through early summer, around May to early June.
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Stop harvesting by mid to late June so plants can recover and store energy.
So traditionally, rhubarb harvest ends by June or maybe July at the latest. But what if you have some left – can you still pick in August?
Can You Harvest Rhubarb in August?
The good news is rhubarb stalks stay completely safe to eat and retain good flavor through summer and August. There is no truth to the myth that late summer rhubarb becomes toxic or excessively high in oxalic acid.
However, there are some important tips for late summer rhubarb harvesting:
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Only harvest a few stalks per plant, not the whole plant. Rhubarb needs to recover and store energy.
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Pick the thickest, largest stalks. Leave smaller, thinner stalks to continue maturing.
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Don’t harvest rhubarb plants that appear small or weak.
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Water plants well after late summer harvesting.
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Add compost or mulch to replenish nutrients.
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Don’t harvest any rhubarb after August. Allow full rejuvenation before winter dormancy.
So while August rhubarb stalks are perfectly edible, it’s still ideal to finish harvesting by mid-summer.
Reasons to Stop Harvesting in Mid-Summer
Even though August rhubarb is safe, here are good reasons to stop earlier:
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Frequent harvesting weakens plants over time by using up energy and nutrients.
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Small, thin stalks need time to bulk up before winter dormancy.
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Rhubarb needs recovery time before going dormant. Too late harvesting reduces vigor and next year’s yield.
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Late summer stalks get thicker, tougher and stringier. Spring and early summer stalks are more tender.
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Overharvesting year after year can kill the plant, which has limited energy to regrow annually.
So for best long-term plant health and maximum yields, it’s best to stop harvesting rhubarb by mid-summer at the latest. But taking a few stalks in August won’t seriously harm the plant if done lightly.
How to Harvest Rhubarb Properly
When harvesting rhubarb, use these tips to minimize damage:
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Grasp the stalk near the base and gently twist while pulling upwards in one smooth motion. Don’t yank or tear.
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Use a sharp knife to remove leaves, leaving some stem. Discard poisonous leaves – do not compost.
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Harvest largest, thickest stalks first. Leave small, thin stalks to continue maturing.
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Never take more than 2/3 of available stalks. Leave at least 1/3 of stems on the plant.
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Allow 8-10 weeks between harvests for recovery. Water and fertilize after harvesting.
Storing and Preserving Rhubarb
Rhubarb is versatile in the kitchen. Use it for:
- Pies
- Cobblers
- Crumble toppings
- Jams and jellies
- Sauces
- Juices
- Smoothies
It also freezes extremely well for long-term storage. To freeze:
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Wash, trim and chop stalks.
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Spread on a sheet pan and freeze solid.
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Transfer to freezer bags or containers. Keeps up to 1 year frozen.
Other options are canning chopped rhubarb or making syrup.
Soil pH and fertility
- The best soil for rhubarb is well-drained.
- Loamy soils are better for rhubarb growth than sandy soils. They hold on to water better and can give plants more nutrients.
- Soil pH is not important. Minnesota garden soil can grow a good crop of rhubarb, no matter how acidic, neutral, or basic (alkaline) it is. Soil tests from parts of the garden where annual plants are grown won’t tell you what the rhubarb plant needs because they are from those areas.
- The rhubarb plant is a “heavy feeder. To make its big stalks and leaves, the plant needs to take in a lot of nutrients from the soil.
- You should add either a balanced commercial fertilizer or rich compost to the soil once a year, or both. Micronutrients and organic matter can be added to soil by adding manure or compost. Write down whether the growth is strong or weak, and then change how much fertilizer you use next spring based on that information.
- Phosphorus builds up in the soil when high-phosphorus fertilizers like 10-10-10 or 15-30-15 are used over and over again, or when a lot of manure or manure compost is used. Some runoff may occur with phosphate fertilizer. Then it can become a big problem for polluting our lakes, rivers, and streams. Too much algae grows when there is a lot of phosphorus in the water, which makes the water quality much worse.
- Check to see if your soil has a lot of phosphorus. If it does, use a fertilizer with little or no phosphorus, like 32-3-10, 27-3-3, or 25-3-12.
Gardeners often acquire rhubarb plants from another gardener who is dividing a large plant. Even though you might get a plant that has a virus on it, the fact that it’s big enough to need dividing means that it’s probably healthy and strong.
You can also purchase plants at garden centers and from mail-order catalogs. Nursery-grown plants will be virus-free.
Catalogs also sell rhubarb seed. The reddest varieties are not available as seed, only as plants.
- Different varieties have varying levels of sourness and fibrousness.
- The color of the different types ranges from almost pure green to almost pure red. The skin is mostly red, and the flesh is a range of shades of green, from light to dark.
- Color does not cause any specific flavors. For pies, redder varieties are better because the filling looks better than cooked green varieties, which are a grayish color.
- Plant stature and vigor also vary among varieties. Most of the time, green varieties are stronger and have longer stalks than red varieties.
- Rhubarb leaves are toxic. Do not eat them.
- Only the long, thick leaf petioles, the “stalks,” are edible. There is a lot of oxalic acid in the stalks, which can bind calcium and stop the body from using it.
- Eating a dish with rhubarb every once in a while is not likely to hurt your health.
- People with rheumatoid arthritis, gout, or kidney problems may want to stay away from foods that are high in oxalic acid. They should also talk to their doctors before eating these foods.
Can you harvest rhubarb in August?
FAQ
When should you not pick rhubarb anymore?
You should generally stop harvesting rhubarb by the end of June or early July. After this point, the stalks can become tough, woody, and less flavorful as the plant focuses on storing energy for the next season.
What is the latest date to pick rhubarb?
In the northern hemisphere, rhubarb harvesting generally stops around the end of June or early July. Continuing to harvest rhubarb past this point can weaken the plant, reducing its productivity in the following year.
Can rhubarb get too big to harvest?
Yes, rhubarb can get too big to handle, and if you leave the stalks on the plant for too long, they can get tough and woody. While you can technically harvest rhubarb until the first frost, it’s best to stop harvesting by mid-summer (around June or early July) to allow the plant to store energy for the next season.