CORVALLIS, Ore. — Garden centers in spring overflow with tuberous begonias — lush plants with brilliant blooms in orange, pink, yellow, white and bi-colored varieties. With their vivid colors and elegant form, they’re hard for gardeners to resist.
Tuberous varieties won’t survive outdoors through winter but can be saved and replanted each spring for another season of color.
“There are so many choices for tuberous begonias,” said Nicole Sanchez, horticulturist with the Oregon State University Extension Service. “They come in so many colors, and there are a lot of new salmon and orange varieties on the market now. In my experience, the yellow ones are always a little less vigorous than other colors.”
Tuberous begonias are not the same as wax begonias — the low-growing bedding plants that behave as annuals. Tuberous varieties won’t survive outdoors through winter but can be saved and replanted each spring for another season of color.
These begonias thrive in bright shade. Too much sun can scorch their leaves, while too little sun makes them spindly.
Avoid the biggest mistake: overwatering
“We can easily love them to death,” Sanchez said. “The biggest problem with tuberous begonias is operator error in the form of overwatering. Lots of water is already stored in the tubers and stems, so be careful to check moisture at least an inch below the surface, not just on top.”
There’s a fine balance between keeping the soil moist enough and letting it dry too much, she said. Begonias do best in well-drained potting soil without peat or sphagnum moss, which hold excess water.
In hanging baskets outdoors, begonias may still need daily watering during hot weather, but avoid letting water collect around the roots.
Feed regularly for strong, lasting blooms
Tuberous begonias are heavy feeders and produce more vigorous growth and larger flowers when fertilized regularly. Sanchez recommends using slow-release fertilizers, which are easier to apply and reduce the risk of overfertilizing. Too much fertilizer can cause leggy growth and weak stems.
Each tuberous begonia produces both male and female flowers. The male blooms are larger and showier. Removing the smaller female flowers directs the plant’s energy into producing more impressive male blooms.
Store tubers for next year’s display
When frost threatens, it’s time to prepare tuberous begonias for winter storage. Sanchez suggests the following steps to save your tubers for replanting:
- Remove the plant from its pot before hard frost. Cut back most of the top growth, leaving the root ball and soil intact.
- Place the pot or root ball in a dry, cool area such as a basement or garage. Let the tubers cure for several weeks.
- After curing, shake off the soil and remove remaining stalks and roots. Any leftover material can rot and spread to the tuber. Place the tubers on screen trays or pack them in dry peat, sawdust, sand or another insulating material.
- Store the tubers in a dark, dry, cool location just above freezing.
- In spring, start the tubers by placing them on damp potting soil in a warm area. When roots and shoots appear, pot them in rich, well-drained soil. Move outdoors after the last frost, placing them in a shady spot.
Previously titled Five steps for saving tuberous begonias as frost approaches
