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Starting Begonia Tubers for Pots and Gardens

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Tuberous begonias bring luscious color to the garden, whether they’re grown in hanging baskets, window boxes, mixed containers or garden beds. Their large, often ruffly flowers are available in a wide range of colors, and their appealing foliage provides the perfect backdrop.

tuberous begonia

Tuberous begonias can be purchased as blooming plants in later spring, but you can save some money by purchasing them as dormant tubers in late winter. You may not feel keen to start seeds indoors because of the time, space and materials (such as artificial lighting) that they require. Starting begonia tubers is a nice alternative. It offers the same rewards but with less effort.

To get your begonias growing and ready to bloom in time for spring, start the tubers indoors in late winter. About 10 weeks before your typical last frost date, set the bare, dry tubers in a warm, bright spot. Within about two weeks, reddish buds will sprout from the tops of the tubers, followed by the beginnings of stems. (The top is the side that’s cupped.)

At this point you can transfer the tubers to pots. Plant them about an inch deep with the sprouts facing up. Use small pots—four inches at the most. This helps prevent rot. Use evenly moist potting mix when planting the tubers. To increase humidity, you can cover the pot with a plastic bag or other clear cover. While the tubers are rooting, water only if the soil dries out. Once leaves emerge, remove the covering and start to water more regularly, but avoid creating soggy soil. Keep the plants in bright light.

When two or three leaves have developed, transplant to a pot a couple of inches larger and continue to grow the plant on toward spring. After all danger of frost has passed and nighttime temperatures remain above 50 degrees (F), you can transition the begonias to their place in the outdoors.

Image credit: Maja Dumat, CC BY 2.0 via