Tuberous begonias come in both upright and trailing varieties, with single and double flowers and a wide range of bright colors and flower shapes. They are a gardener’s favorite for quickly brightening up a shady spot in the yard. They won’t last through harsh winter weather outside, so they have to be dug up in the fall and kept inside all winter.
Now is the time to begin thinking about getting them out of storage and ready for spring planting. Here are some dates and steps that horticulturists from Iowa State University Extension and Outreach say are best for starting tuberous begonias.
Tuberous begonias are stunning plants that can add a pop of color to gardens, patios, and balconies. With their showy flowers and attractive foliage, it’s no wonder they are so popular. While tuberous begonias are not cold hardy and must be started indoors in most climates, they are surprisingly easy to get going. With a little planning and TLC, you can have gorgeous begonias in bloom by mid to late spring.
An Overview of Tuberous Begonias
Tuberous begonias belong to the Begoniaceae family and Begonia genus. There are over 1,800 species of begonia, but tuberous begonias are classified as Begonia x tuberhybrida. These tender perennials grow from bulbs, which are actually modified stems called tubers.
The tubers store food and energy to fuel new growth each year. Tuberous begonias come in a variety of flower forms, such as double, semi-double, fringed, and more. The plants grow 6 to 18 inches tall depending on the variety. Flowers come in many colors like red, pink, white, yellow, and orange. The attractive foliage is just as much of a showstopper as the blooms. Leaves come in various shapes and sometimes display unique patterns.
Tuberous begonias require warm temperatures and perform best in partial shade locations. They make excellent container and hanging basket plants. In zones 9 to 10, tuberous begonias can be grown outside as annuals. But in most climates, they must be started indoors to get a jump on the growing season.
When to Start Tubers Indoors
Tuberous begonias require a long grow time before they reach maturity and begin blooming. To maximize your growing season, start tubers 8 to 12 weeks before your last expected spring frost.
For many gardeners, the optimal window is February to March. However, the timing depends on your climate and target bloom time. If you start tubers too early, the plants may grow leggy and weak while waiting for outdoor planting time. But starting too late will delay flowering.
Check your local frost dates and make sure to account for begonias’ long grow time when deciding when to begin. Give your plants adequate time to establish before moving them outside where they will really take off.
Step-by-Step Guide to Starting Tubers Indoors
Follow these steps for successfully starting tuberous begonias inside
Choose Tubers
Purchase top quality tubers from reputable suppliers that provide large, firm tubers ideal for propagation. Avoid shriveled tubers or those with mold, lesions, or signs of rotting. Select named begonia tuber varieties suited to growing indoors and your climate.
Plant in Pots
Fill 4 to 6 inch pots with a well-draining potting mix Create a hole and place 1 tuber per pot with the indented side up. Cover the tuber with 1/2 to 1 inch of soil Gently water until moisture seeps from the drainage holes at the bottom.
Provide Warmth
Put your newly potted begonia tubers in a warm (70 to 75°F) place. Cover the pots loosely with clear plastic to keep the soil lightly moist (not wet). The tubers themselves should stay relatively dry.
Give Light
When the sprouts are about a half inch tall, move the plants to a warm, sunny windowsill or put them under grow lights. Turn the pots occasionally so growth remains even. Once sprouted, tuberous begonias require 12 to 14 hours of bright light per day. Supplement with grow lights as needed.
Monitor Watering
Keep the soil consistently moist but not saturated as the tubers sprout and plants grow. Water whenever the top inch of soil becomes dry. Avoid overwatering which can lead to rotting. Monitor pots regularly and adjust your watering routine to maintain ideal soil moisture.
Fertilize Occasionally
Apply a balanced liquid fertilizer like a 10-10-10 or 20-20-20 at half strength every 2 to 3 weeks. Fertilize lightly to prevent leggy, weak growth.
Harden Off & Transplant
Over 2 to 3 weeks, gradually introduce your begonias to the outdoors to harden them off. Transplant into the garden or containers after the danger of frost when soil and air temperatures have warmed.
Tips for Success
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Disinfect pots and trays to prevent disease. Sterilize any tools you use between pots with isopropyl alcohol.
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Invest in a seedling heat mat to provide bottom warmth between 70 to 75°F. Fluctuating temperatures can cause uneven sprouting.
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When sprouts emerge, move pots to brighter light immediately to prevent leggy growth.
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Turn plants frequently so they grow straight and evenly.
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Allow the soil to dry slightly between watering to prevent tuber rot and overwatering issues.
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Transplant begonias outside only after hardening off and when all danger of frost has passed.
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Hold off on heavy feeding until begonias are established outside in the garden.
Enjoy Months of Brilliant Blooms
Although they require some forethought and planning, starting tuberous begonias from tubers indoors is very rewarding. In just 2 to 3 short months, you’ll have thriving begonias ready to grace your garden beds, patio pots, window boxes, and more. Just be sure to get tubers started at the right time for your climate. Provide bright light, consistent moisture, and proper hardening off. With the right care, your tuberous begonias will thank you with months of brilliant blooms.
When should I plant tuberous begonia tubers indoors?
Plant tuberous begonia tubers indoors eight to 10 weeks before the average last spring frost in your area. (Flowering typically begins 12 to 14 weeks after planting. ) Start tuberous begonias in pots or other suitable containers. All containers should have drainage holes in the bottom. Use a well-drained potting mix. When planting the tubers, place the concave or indented side upward. The rounded side is the bottom. Cover the tubers with one-half to 1 inch of potting soil. Water well. Then place the containers in a warm, 70 degree Fahrenheit location. Since the tubers are susceptible to rotting, keep the potting soil moist, but not wet. Once the tubers sprout, move the plants to a sunny window or place under fluorescent lights. Fertilize plants with a dilute fertilizer solution every two to four weeks.
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AMES, Iowa — Tuberous begonias are available in upright and trailing types, single and double flowers and a wide variety of vibrant colors and flower forms and are a gardener’s favorite for easily brightening a shady corner of the garden. Unfortunately, they will not survive harsh winter weather outdoors and must be dug in the fall and stored indoors through the winter months.
Now is the time to begin thinking about getting them out of storage and ready for spring planting. Here are some dates and steps that horticulturists from Iowa State University Extension and Outreach say are best for starting tuberous begonias.
How to Start Tuberous Begonias Indoors
FAQ
How do you wake up tuberous begonias?
When to start tuberous begonias indoors?
Should I soak begonia tubers before planting?
How do you start begonias after winter?
When should I start my Begonia tubers?
Pre-start your begonia tubers inside, 8 weeks before the last frost. As previously mentioned, begonia tubers won’t survive in cold weather so you will want to start them indoors. Follow these easy steps to give your begonia tubers the best start in life: You can buy your tubers in garden centres between January and April.
How do you grow tuberous begonias?
If you are growing tuberous begonias in the ground, allow these plants to grow as long as possible up to the first frost. At this point, dig up the tubers with a small amount of soil around them and allow them to dry in a sheltered location like a garage or shed.
How long does it take to grow a tuberous begonia?
Dormant or store-bought tuberous begonias can be started indoors in late winter or early spring (about 8 weeks before the last frost) by placing them in a warm area with indirect light to reacclimate and sprout. This should take a few weeks.
Do tuberous begonias need to be dug up?
In most areas, tuberous begonias will need to be dug up and saved over the winter, so keep that in mind when placing your plants so you can easily access the tubers when it is time to overwinter. Tuberous begonias also work well in containers on shady patios and porches with filtered sunlight.
How to care for begonias indoors?
Care of begonias indoors starts with the proper location. One of the tips for growing begonia as houseplants is to place them somewhere where they will get bright, indirect light and will get plenty of humidity.
How do begonias grow?
These begonias are grown for their showy flowers and typically have a rounded growth habit. They grow from underground tubers, which store nutrients and energy for the plant. Tuberous begonias often have large, double blooms in a wide range of colors, including red, pink, orange, yellow, and white.