Growing Organic Rhubarb

Rhubarb report

Growing Rhubarb is considered a vegetable in most of the world. However, in 1947, a New York judge ruled that rhubarb is a fruit, thereby lowering taxes.

Growing Rhubarb in the U.S. began in the 1820’s when it was first imported to Maine and Massachusetts. Early settlers took plants with them as Americans migrated West.

In the Middle Ages, rhubarb was grown in China and was more expensive than spices like cinnamon because it had to be (they thought) imported from China – which at that time was a good thing!

Laura Ingalls Wilder, in her book “The First Four Years,” refers to growing rhubarb as growing “pie plant.” Rhubarb pie is still a favorite of many people, including myself! drivingschoolintoronto

When to Plant Rhubarb

If you’re starting rhubarb from seed, plant the seeds about 6 weeks before the last frost. Do note, though, if you plant from seeds rather than root stock, you’ll wait at least 2 years (1 additional year) to harvest your rhubarb roots.

If you’re planting from root stock or crowns, plant or divide the roots/crowns in early spring while the plants are still dormant. This is the favored method for planting rhubarb, particularly in the Northern climates.

Rhubarb, once planted in Northern climates like where we live, will thrive in the cooler spring temperatures. It begins growing once soil temps reach a little over 40°F.

You can also plant roots/crowns before the ground freezes in the fall, provided you mulch over top of your plants with 8 to 12 inches of mulch.

Rhubarb generally does not do well in Southern U.S. climate zones due to not liking temperatures over 90°F. However, it can be grown during the cool season in some sub-tropical and tropical areas.

Best Planting Areas for Rhubarb

In the Northern areas, where rhubarb thrives best, rhubarb requires at least 8 hours of sunlight daily to flourish. In Southern climates, some afternoon shade is preferable, but does create more spindly stalks.

As with most plants, rhubarb doesn’t really like soggy soil. Make sure the area you plant it in has well-draining soil with lots of organic matter in it.

Preparing the Soil

The ideal pH level for growing rhubarb is about 5.5 to 6.5.

Rhubarb needs a good amount of nutrients to grow well. The best organic methods will include mixing lots of compost or composted manure into an area at least 12 inches deep and 3 feet in diameter. Mix in about 6 inches of compost/composted manure.

Choosing the right Varieties for your Area

Many rhubarb plants, if grown in good soil with adequate sunlight, have a mature diameter of 5 to 6 feet. Happily, one plant is usually enough for most families.

Some of the new varieties of rhubarb have red to crimson stalks that are sweeter than some of the older varieties. Check with your favorite seed supplier for their advice on which varieties will fit your tastes best.

Check with your county extension office to see if there are any common diseases that afflict rhubarb in your area. If there are, they will be able to recommend resistant varieties.

One reason rhubarb does better in cooler climates is that it needs the ground temperature to drop below 40°F for at least a week to break dormancy and stimulate the rhubarb leaves to grow. temp-mail

Getting Started Indoors

If you’re planting rhubarb seeds, soak the seeds for a few hours in water or a compost tea before planting in a good quality, sterile potting soil; the seedlings will take 2 to 3 weeks to come up.

Don’t use ordinary garden soil as it may have fungus, weeds, bacteria, or other things that can hamper your plants.

Plant the seeds about a ¼ to ½ inch below the surface of the soil. Plant 2 to 3 seeds per section or pot. Once 4 true leaves have formed, cut off the weaker plants.

Transplanting Rhubarb Outdoors

Most rhubarb is sold as dormant roots or crowns. Purchasing them this way from your local garden center or favorite mail order seed company will take a full year off getting to your first harvest.

If you planted seeds, though, you’ll need to “harden off” your plants off for at least a week before planting out in the garden. You’ll do this when the plants are 4 to 6 weeks old and are about 3 to 4 inches tall.

This simply entails moving your plants outdoors during the day and back inside at night for increasing lengths of time throughout the week.

Ideal temperatures at this point should be about 50° to 55°F at night and 70° to 75°F during the daytime.

If you’re planting crowns or roots, place them 1 to 2 inches below the surface of the soil. If you’ve purchased potted plants, plant them at about the surface level of the soil.

Give the plants at least 36 to 48 inches between the plants and at least 72 inches between your rows if you are planting a lot of rhubarb.

Planting Seeds in Your Garden

Except for Southern climate zones, planting seeds directly in your garden is not recommended, but if you live in the South, you can plant rhubarb in rows 72 inches apart.

Plant the seeds every 3 to 4 inches, then once the plants have reached 3 to 4 inches in height, thin them out to at least 36 inches apart as they’ll grow quite large in the next couple years.

If you’re planting crowns or roots, plant them 36 to 48 inches apart. Cover the roots 1 to 2 inches deep, but don’t cover the crowns.

Best Practices for Getting a Good Rhubarb Crop

Here are a few tips to getting the best rhubarb crop from your garden.

During the first year, remove any flower stalks when they grow from your plant. This will give your plant more energy to put into the roots which will grow a stronger plant in subsequent years.

You’ll see flower stalks growing out from your plant as the weather warms into the summertime. Your plants may resume growth in the fall when the weather cools.

When the frost begins in the fall, the heavier frosts will usually kill the rhubarb plant that’s above ground. This is the time to fertilize for next year’s crop.

Dividing Rhubarb for Better Yields

As rhubarb gets older – around 8 to 10 years – the plants often become root-bound. There becomes such a mass of roots that the rhubarb plant yield often decreases.

This is the time to divide the rhubarb plants to help them regain their vigor. This is pretty much like replanting new root stock, so follow the procedures outlined above.

When you divide these plants, you can typically cut the old crown into 4 to 8 pieces. Just make sure each section has one strong bud.


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