How to Winter Over Tuberous Begonias

Tuberous begonias are popular garden flowers that bloom all summer long in bright, beautiful colors. However, they are not hardy in cold places and need extra care to make it through the winter. You can save the tubers to plant again next year if you store them properly over the winter. Here is a step-by-step guide on how to keep your tuberous begonias alive over the winter.

When to Begin Wintering Over Tuberous Begonias

The process of wintering over tuberous begonias should begin in early fall, before the first frost hits. Here are some tips on when to start

• If you live in a place with a set date for the first frost in the fall, start wintering over about one to two weeks before that date.

• If it doesn’t freeze, start when the plants start to lose their health, such as when they wilt, turn brown, or lose leaves.

• When the temperature drops below 50°F at night, bring plants in pots inside. Plants in the ground will need to be dug up.

• Allow the plants to die back naturally after the first light frost. Once they are blackened by frost, it’s time to move to the next steps.

Digging Up and Removing Foliage

After the begonias have been blackened by a light frost, it’s time to dig them up:

• Carefully dig up each plant, keeping the root ball and soil intact.

• Use pruners to cut off the foliage and stems down to about 1 inch above the soil line.

• Remove any loose or excess soil from the root ball.

• Discard all above ground growth, leaving only the soil-covered tubers.

Curing and Drying the Tubers

After digging up the tubers, they need to be cured and dried:

• Spread out the tuber clumps on newspaper in a sunny location. Allow to dry for 1-2 weeks.

• Once dried, gently remove any remaining roots or foliage. Shake off any loose soil.

• Dust the tubers with sulfur powder to prevent rot and fungus.

• Pack the tubers loosely in sawdust, peat moss, vermiculite, or cardboard boxes for storage.

Storing Tubers Over the Winter

Proper storage conditions are vital for overwintering tuberous begonias successfully:

• Store the tubers in a cool area between 40-50°F. The temperature should not go below freezing.

• Choose a dark, dry spot for storage, like a basement, garage, or root cellar.

• Avoid storage areas that get too warm, which can cause early sprouting.

• Check regularly over winter. Discard any tubers that are diseased or rotting.

Planting Tubers in Spring

In early spring, you can begin the process of planting the overwintered tubers:

• In late winter or early spring, move tubers to a warmer spot to initiate new growth.

• Plant the tubers sprout-side up in rich, well-draining potting mix once the sprouts emerge.

• Keep them in a sunny indoor area, around 70°F until all danger of frost has passed.

• Gradually acclimate them to outdoor conditions over 7-10 days before moving outside permanently.

Tips for Overwintering Success

Follow these tips to successfully overwinter your tuberous begonias:

• Select a variety suited to overwintering when buying tubers. Doubles and fringed varieties may not store as well.

• Make sure tubers are completely dry before storage. Any moisture can lead to rot.

• Use sulfur powder and dry storage mediums to prevent fungal or bacterial rot issues.

• Check regularly over winter and remove any diseased or damaged tubers.

• Repot in fresh, sterile potting mix in spring to prevent disease carryover.

• Move tubers outdoors gradually in spring to prevent transplant shock.

By carefully following these steps for digging, drying, storing, and replanting your tuberous begonias, you can save them to enjoy their beautiful blooms year after year. With a little diligence and care, you’ll be rewarded with thriving, hardy begonia plants.