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How to Harvest Rhubarb in the Home Garden

Our garden is the farm's pride and joy. We love spending time in it, and preparing meals out of our fresh produce.

Introduction

Rhubarb is one of the easiest and most prodigious perennials you can grow in your garden. Not only that, it is incredibly easy to harvest. Once planted, you will be rewarded with an abundant yield for years to come.

While not ideal for eating raw (though one of our customers at a farmer’s market bought a bunch of the tender stalks and walked around snacking on them), rhubarb is delicious when baked into pies, crisps, or made into sauce.

Let’s look at how to tell when your rhubarb is ready and how to harvest it.

What Parts of the Rhubarb Plant Are Edible?

Only the stalks of a rhubarb plant should be eaten. A rhubarb plant grows from a perennial crown, which sends up numerous stalks (or petioles) that end in large, fan-like leaves.

All parts of a rhubarb plant contain oxalic acid which give the vegetable its sour flavour. When eaten in large quantities, oxalic acid can cause diarrhea, vomiting, and can lead to kidney failure. Most of this toxin is contained in the leaves (which is why they should be discarded) and though the stalks contain large quantities of oxalic acid, you would have to eat a lot of rhubarb for it to cause a problem.

Waste not, want not

Even though the leaves should not be eaten, they do not have to go to waste. Add them your compost pile or use the extra large leaves as a mulch between rows of your vegetables.

Many of us grew up hearing rhubarb becomes poisonous after mid-summer. This is an old tradition where the oxalic acid is thought to increase as the plant matures. Studies have shown that this is probably untrue, and I have personally eaten rhubarb harvested from our garden in late August. However, there is some evidence to suggest that when the leaves wilt or are frosted that some oxalic acid may transfer to the stalks, making them less safe to consume.

If in doubt, play it safe and don’t eat it!

Harvest Rhubarb From Early Spring To Mid-July

Rhubarb is a cool-season plant and its growth and quality tapers off during the heat of the summer. Harvest your rhubarb from early spring to mid-July. Because it is such a quick-growing plant, you will probably get 2 to 3 harvests during this time.

You can harvest a few stalks as needed while your plant is growing. This will help thin out the plant and encourage good growth. However, we find it best to harvest all the stalks several times throughout the growing season. In our experience, any stalks left on the plant all season long will become tough, over-mature and will die and rot on the crown.

When you can harvest rhubarb depends on your local growing season, but here is a rough guideline:

Early Spring

In early to mid spring, your rhubarb plant will probably be large enough to harvest the entire plant. If the plant is not big enough yet, harvest a few of the larger stalks and let the others continue to grow.

Late Spring or Early Summer

A few days after your first harvest, dozens of new leaves will shoot up. By the early summer, the rhubarb will have regrown enough for a second harvest.

Mid Summer

Depending on your climate, you can often get a third harvest. Regrowth at this point will be slower.

Late Fall Cleanup

Even though regrowth over the summer will be slow, the rhubarb will finish the year with a decent amount of foliage. Before the first killing frost, remove all stalks and add them to the compost. Any stalks and leaves left on the plant over winter will become a gooey rotten mess that will have to be cleaned up in the spring.

What Time Of Day Is Best To Harvest Rhubarb?

As with most plants, rhubarb is best harvested in the morning. This is because the plants take on water and convert starches into sugars during cool nights.

However, the thick leaves and tough stalks of the rhubarb plant are not as susceptible to wilting from the heat as some of the more delicate vegetables in your garden. If you do harvest during the heat of the day, protect the newly picked stalks from the sun by keeping them in the shade.

Yield Of A Rhubarb Plant

The yield of your rhubarb plant will vary greatly depending on the variety, growing conditions, and your climate. Most references online say you should expect about 1kg to 3kg (2-6 lbs) per harvest per plant and to grow 2 to 3 plants per family member.

In our garden, we get upwards of 10kg (22lbs) per harvest from a single plant (so a plant yields about 30kg each year) and one plant is more than enough for our family.

How to Tell Rhubarb is Ready to Harvest

The best way to tell if rhubarb is ready is by the size of the stalks. Here are a few indicators if your rhubarb is ready or not:

Size of the stalks

The ideal size for a rhubarb stalk at harvest is 30cm (12 inches) long and about 1.25 cm to 2.5 cm (1/2 to 1 inch) in diameter. That being said, we have harvested them at half the size (these are the best for eating raw) and some over a meter long and as thick as your wrist.

Make sure the plant is established

It is best to wait until there are at least 10 stalks on the plant before harvesting. Otherwise, you might set the plant back too much and delay its growth.

This is especially true if your plants are young. A newly established plant grown from a root cutting or nursery stock will need to establish itself and might only yield one harvest the first year. A rhubarb plant grown from seed might take 2 to 3 years before it is established enough to harvest.

Does red mean ripe?

The colour of the rhubarb stalks is not an indicator of ripeness but is determined by the variety you are growing. Some rhubarb varieties are green, some are deep red, and others are a red/green mix.

Rhubarb Flowers

In late spring or early summer, rhubarb plants will send up thick stalks that will develop flower buds and go to seed. The flower stalks themselves are woody and inedible but the rest of the plant is fine, and the flowers do not affect your harvest.

Once the plant flowers, all of its energy goes into seed production. If it us early in the year and you still want to encourage new stalk growth, it is best to remove any early flower buds.

As the year progresses, you can leave the buds to go to seed (they are quite pretty and unique) or you can remove them. We have removed the buds and left them with equally good results.

A rhubarb flower

A rhubarb flower

How To Harvest Rhubarb

Rhubarb is easy to harvest and this is best done by hand. Here is a step-by-step guide to harvesting your rhubarb.

Step 1. Twist Off the Stalks

Take a firm grip on the stalk as close to the base as possible. Twist the stalk while pulling. Most stalks stalk will come with a gentle tug, but sometimes you really have to pull on it. Twisting breaks the stem off right at the crown and encourages new growth.

Do NOT cut the stalks

Cutting the stalks from the crown leaves behind a small stub that will quickly rot, making a gooey mess to clean up in a few weeks.

Step 2. Remove the Leaves

Twist or cut off the leaves. To twist them off, grasp the stalk with both hands just below the leaf and twist while pulling your hands apart. Alternatively, use a sharp knife or a pair of garden shears to cut the leaf off.

Step 3. Remove the Base of the Stalk

Sometimes, part of the plant crown will be attached to the base of the stalk. Remove this like you would the leaves, and put the cut end in the compost.

Storing and Preserving Rhubarb

Rhubarb stores and preserves very well. Here are the best ways to keep your harvest:

Store in the fridge: Freshly harvested rhubarb will last about a month in your refrigerator. Leave the stalks unwashed (or dry them well) and whole if possible.

Frozen: Slice your rhubarb into pieces about 1 cm (1/2 inch) wide. Freeze them on a cookie sheet and then put them in an airtight, freezer-safe container.

Frozen rhubarb will last for about a year, or until it becomes icy and freezer burnt.

Dehydrated: Cut your rhubarb into pieces about 1 cm (1/2 inch) wide and dehydrate them according to your dehydrator’s instructions. They can also be dehydrated on a tray in the oven.

Put the dehydrated rhubarb into a jar or other airtight container and store it for about a year.

Canned: There are several ways to can rhubarb and many delicious recopies to make. Make sure you carefully follow the directions of your canner.

Conclusion

Knowing when to harvest your rhubarb is important to ensure you get the best tasting, most nutritious rhubarb possible. I hope this article had shown how easy it is to grow and harvest rhubarb of your own.

An established rhubarb plant is nearly indestructible, and it is very hard to kill by accident or mismanagement. Our rhubarb has been through a lot, both from us and from the elements, yet it still thrives and produces huge amounts of stalks each year.

Once your plants are established, you had better stock up on sugar so you can turn this sour vegetable into countless delicious desserts.

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

© 2021 Bellwether Farming

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