How to Grow and Care for Tuberous Begonias

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Begonias are part of a group of over 1,300 species and 10,000 cultivars! These are divided into 7 groups: cane-like, rex-cultorum, rhizomatous, semperflorens, scandent or trailing, shrub-like, and tuberous. 

Tuberous types are some of the most popular flowering Begonias and are generally grown as annuals in cold climates or overwintered for re-planting the following year.

History

These plants were first discovered in Mexico as far back as the 1500s, and have since been found in many areas of the subtropics.

Begonia flowers come in many forms and colors, which makes them firm favorites for container planting and beds and borders!

Plant Facts

Scientific nameBegonia spp.
Common namesBegonia, Tuberous Begonia
GenusBegonia
FamilyBegoniaceae
Height1 ft. 0 in. – 1 ft. 5 in.
Width1 ft. 0 in. – 1 ft. 5 in.
USDA Plant Hardiness Zone9a, 9b, 10a, 10b, 11a, 11b
OriginSubtropics except for Australia
Flower colorsRed, Pink, White, Yellow, Orange
Blooming seasonSummer, Fall
Plant/Flower special featuresExotic flowers and foliage

How to Plant and Grow Tuberous Begonia Bulbs

Different Begonias have different growth habits, so doing some research is recommended to get the most out of your plant. 

Tuberous Begonias are well-suited to container planting and hanging baskets. Whereas hardy types are preferred for bed and border planting, especially since they can be left in the ground during winter in milder climates. 

These plants can either be bought or started from the previous year. Start the bulbs off in February for a June blooming or March/April for a July blooming, making sure temperatures are at least 64°F outside.  

Bulbs need to be put 1-inch deep in a tray of moist, sandy, potting mix, with the hollow side facing up. Keep the medium moist at 70°F and place in an area with bright, indirect light. After one month, transplant them to a larger container. Harden them off for two weeks after the danger of frost has passed before planting them outside.

Growing Tuberous Begonia Flowers in Beds

Dig holes deep enough to plant bulbs 2-3 inches deep in the ground and water well to settle in. Pinch back any forming buds or flowers to promote branching. 

Dwarf varieties should be spaced a minimum of 8 inches apart, and normal types should have at least 12 inches between them.

tuberous begonias

Growing Tuberous Begonia Flowers in Pots

When growing tuberous Begonias in pots, plant tubers 2-3 inches deep in a well-draining potting mix, grouping 3-4 plants per container for an attractive display.

Overwintering Begonia Bulbs

Tuberous Begonias go dormant in winter, lift them before the first frost and store them in a dry place at 45°F. Water sparingly to stop them from drying out. In milder climates, hardy types are able to be left in the ground and will return the following year. 

How to Propagate Tuberous Begonias

For division, start plants as usual, once shoots have emerged, divide the tubers ensuring each section has roots and one growth bud. Transfer to pots, and once calluses form (a few hours), plant the tubers level with the soil line.

For stem cuttings, take 4-inch cuttings in April, remove bottom leaves and insert them into a sandy rooting mix. Keep the bottom temperature at 64-70°F. For better success, leave a section of a tuber on each cutting, however, this can increase the risk of fungal problems so space cuttings out.

tuberous begonia

Care and Maintenance

Soil

Grow tuberous Begonias in organically rich, well-draining soil. Improve the aeration in clay soils and water retention in sandy soils by amending with pine bark humus or well-rotted manure.

Water

Water plants regularly during the growing season, taking care not to water them too much as they can develop root rot. From August, begin preparing plants for winter dormancy by gradually reducing watering.

Fertilizer

Regularly fertilize the plants using a liquid fertilizer at half the recommended strength, but twice the frequency. Reduce fertilization from August to prepare plants for the winter dormancy period. Mulching is recommended and is crucial in winter for hardy types that will be left in the ground.

Sunlight

Tuberous Begonia flowers prefer dappled or partial shade. Early morning and late afternoon sun won’t burn them, but at other times they need good indirect light.

Temperature and Humidity

They are sensitive to high heat and humidity and in general, are winter hardy to USDA zones 9-11; however, some hardy types can be grown in zones as low as 7. In milder areas, hardy types can be left in the ground year-round, provided they have a layer of winter mulch and are positioned next to a south-facing wall. 

Pest and diseases

These plants are at risk of powdery mildew, root rot, and fungal problems. These risks can be reduced by taking care not to overwater, and by leaving enough space between plants to allow for good airflow. 

Watch out for mealy bugs, thrips, spider mites, snails, and slugs. Begonias may be sensitive to insecticidal soaps, so be careful when using this pest remedy. 

Pruning

These plants do not require pruning, however, some gardeners will remove any flower buds that form during September to encourage energy storage in tubers before dormancy.

Uses of Tuberous Begonias

These beautiful flowers are extremely popular as ornamentals and are used as both outdoor and indoor plants. 

Worldwide, Begonia plants have been used as food and for their medicinal properties. In Nepal, tuberous Begonia B. rubella has been used to treat wounds, chest pains and to cure boils. People also eat their petioles which are described as having a sour taste.

Common Varieties and Cultivars

Here are some beautiful and popular tuberous Begonia varieties:

  • (B. grandis) Heron’s Pirouette 
  • (Hybrid) Garden Angel Blush 
  • (Hybrid) Hanging Basket Pink
  • (Hybrid) Picotee Calypso
  • (Hybrid) Roseform White

Conclusion

Tuberous Begonias are part of the genus Begonia, which has over 1,300 species. Generally hardy to zones 9-11, they can be grown in colder climates if tubers are stored over winter. Some hardy varieties can be left in the ground over winter in mild climates.

Propagate tuberhybrida begonias using division or cuttings and plant them in hanging baskets, containers, beds, or borders. These plants are valued worldwide for their medicinal properties and as food, and their lovely flowers make them worthy of any garden!

~ image source: depositphotos/Ruvo233