Rhubarb is a cold-hardy perennial vegetable that dies back each winter before erupting with vigor each spring. While rhubarb can withstand cold temperatures, providing some care as the plant goes dormant will ensure the crowns and roots remain healthy for many years of abundant harvests. Here is a step-by-step guide to winterizing rhubarb for a bountiful spring crop.
Stop Harvesting in Early Fall
It’s important to stop harvesting rhubarb several weeks before the first frost in your area, usually by early fall. This gives the plant time to recover its energy stores in the roots and crowns before going dormant. Cutting off all remaining flower stalks and allowing the leaves to die back naturally signals to the plant it’s time to prepare for winter.
Remove Dead Leaves and Stems
Once the leaves have completely died back after the first hard frost trim off all the dead foliage. This removes hiding spots for pests and exposes the crowns to the elements, which helps trigger dormancy. Take care not to damage the crowns as you cut back the dead leaves.
Apply Nutrient-Rich Compost
Before the ground freezes, work 2-3 inches of well-aged compost into the soil around your rhubarb plants. This organic matter feeds the microbes in the soil over the winter while also protecting the crowns. Compost enhances drainage and moisture retention come spring.
Mulch Crowns After Ground Freezes
After several hard frosts when the ground has frozen solid apply a 4-6 inch layer of shredded leaves straw, or other loose mulch over the rhubarb crowns. This insulates the crowns from dramatic temperature swings without blocking exposure to cold they need for dormancy. Wait until the ground has frozen so rodents aren’t tempted to nestle into the mulch.
Consider Protective Structures
In very cold climates, a quick-hoop tunnel or cloche over the rhubarb plants will provide extra insulation while still allowing airflow. Just be sure to remove any plastic or fabric coverings once daytime temperatures warm above freezing so the plants don’t break dormancy too soon
Divide Overgrown Clumps
If your rhubarb plants have become overgrown with woody cores, early spring before growth resumes is the best time to divide them. Carefully cut the roots with a sharp knife, ensuring each division has 2-3 healthy buds. Replant divisions 2-3 feet apart.
Start Seeds for New Plants
You can start rhubarb seeds indoors in late winter to transplant into the garden after the last spring frost. This lengthens the harvest season. Prepare seeds in January and grow transplants under lights until they can be moved outside 8-10 weeks later.
Allow Time to Recharge
Avoid harvesting any rhubarb stalks the spring immediately after division or starting seeds. This gives the plants time to build up their energy reserves. Just remove flower stalks as they appear. A full year of uninterrupted growth is ideal before harvesting again.
With the proper winter care, rhubarb will come back healthy and strong each spring for 20 years or more. The forced dormancy period is crucial to good production. Follow these tips for winterizing your rhubarb plants and you’ll be rewarded with abundant early spring harvests.
How to Winter Over Rhubarb Crowns
If you put mulch around the crowns and make sure the soil drains well, they will be fine even in hard freezes. Rhubarb plants require a cold period to grow. This means that you can fool a plant into producing stems even out of season. Dig up the crowns in late fall and put them in a pot. Let them stay outside during at least two freeze periods. Then move the crowns inside where the crown will warm up. Put the pots in a dark area and cover the crowns with peat or sawdust. Keep them moist and harvest the stems when they are 12 to 18 inches (31-45 cm. ) high. The forced stems will produce for about one month.
Protecting rhubarb in winter will ensure healthy crowns that will produce a lifetime. Divide the crowns every four to five years. Pull away the mulch in early spring and dig up the roots. Cut the crown into at least four pieces, making sure each one has several “eyes” or growth nodes. Replant the pieces and watch them produce new healthy plants. If your zone says to, either dig up the plant and freeze the crown, or put a new layer of organic matter on top of it. Alternately, plant seeds in flats in September and transplant seedlings outdoors in late October.
Rhubarb Winter Care in the Warm Zones
Rhubarb plants that are grown in warmer areas won’t get the cold weather that the crown needs to grow spring stems. Florida and other tropical to semi-tropical zones must plant crowns that have winterized in northern climates annually. Overwintering rhubarb in these zones will require removing the crowns from the ground and providing a chilling period. For at least six weeks, they have to be frozen, and then the temperature has to slowly rise before they can be planted. Using this method to winter over rhubarb is cumbersome and fills up your freezer. Warm season gardeners would do better to purchase new crowns or start rhubarb from seed.
Preparing Rhubarb For Winter.
FAQ
Do you cut back rhubarb for winter?
Do you pull rhubarb at end of season?
How to preserve rhubarb for winter?
Will rhubarb survive a hard freeze?
How do you prepare rhubarb for winter?
If you live in a growing zone that does not experience cold winters, you will need to be more proactive in preparing rhubarb for winter. You will need trim your rhubarb and dig up the crown. It will then need to be frozen for 7-9weeks and gradually readjusted to outside temperatures again.
How do you care for rhubarb in winter?
Caring for rhubarb over the winter period involves: Potentially moving pot-grown rhubarb undercover to overwinter. Removing any old or dying foliage from the plant. Mulching the rhubarb crowns with organic matter. Dividing more mature plants if necessary. This process is explained in more depth in this guide.
Should rhubarb be covered in winter?
Don’t cover the actual crown of the plant with compost in winter. Rhubarb needs temperatures below freezing to trigger its winter dormancy, so in a relatively mild climate like the UK “protecting it from frost” with a layer of compost or whatever is a bad idea. Remove any dead leaves that are covering the crown of the plant for the same reason.
How do you divide rhubarb in winter?
In winter when the rhubarb is dormant, simply lift the crown with a spade from the soil and split it into 2-3 pieces using a knife, ensuring that each new division has at least 1-2 new buds. “I like to use an old bread knife for dividing plants,” shares Dan Ori, a Master Horticulturist.