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Complete Guide to Growing Begonia Tubers


Beautiful Shade Loving Blooms for your Beds, Baskets, and Containers!

With over 350 species of begonias in existence, these shade-loving beauties are easily one of my favorite summer-blooming bulbs! My mostly shaded property has allowed me to experiment with the various begonia varieties, which I have grown increasingly fond of over time. At the garden centers where I worked in the past, I would see begonias cascading from hanging baskets or the accent piece in a patio planter. I was drawn to their large and showy rose-shaped blooms.  If you purchase begonias from a garden center that are in pots or baskets the first step and typically most difficult step in growing begonia tubers is complete: the step of getting the tubers to sprout and grow. Buying begonias as bulbs as opposed to a started plant can be a cost-effective way to enjoy begonia tubers in pots, containers and hanging baskets all summer!

If you want to successfully grow begonia tubers this year read on for our complete guide to growing begonias, from starting begonias indoors all the way to what to do with the tubers in winter.

Get Growing: Starting Begonias Indoors

When growing begonias from tubers, it is very common to get the tubers started in containers indoors. Begonias are frost sensitive and do not do well in temperatures below freezing. Therefore the majority of gardeners in the United States start their begonias indoors in March and April.  Begonia tubers take 6-8 weeks from planting to sprout, which is another reason that starting them inside during the colder months of the year is a good idea. By starting the tubers early in late winter and early spring you allow for growth before you take the bulbs outside; resulting in fuller plants and earlier blooms during summer months.  If you are wondering where to get begonia tubers to start indoors, online garden retailers like Holland Bulb Farms and Tulip World begin shipping their begonia tubers in late February and early March.

Follow these steps to starting your begonia tubers indoors

  • Find a pot, hanging basket or shallow tray that has drain holes.
  • Fill your containers with planting mix that is light, loose and drains well. Potting soil for container gardening works well.
  • Plant bulb hollow side up, just below the soil level. To determine which side to plant up, feel for tiny points on both sides. These points will be the source of new growth. Look for any presence of old roots – they will be dry and small. If you can’t determine which side is up, simply place the tuber on its side.
  • Place the container on a window sill or other location that receives indirect sunlight. Be sure the temperature in this location does not fall below 60°F. Cover pot with paper or plastic wrap to promote sprouting. Water sparingly until growth begins this is very important as the tubers are sensitive to rotting if overwatered.
  • Once the tubers begin to sprout (approx. 6 to 8 weeks), development of leaves and stems become more rapid. Remove the paper or plastic covering and expose the tubers to more light. However, you will still need to protect the tubers from the strong direct midday sun. Water regularly, never allowing the soil to dry out completely but being sure not to let them sit wet as this will cause rotting.
  • Once the threat of frost has passed, you can move the plants outdoors. The tubers can be left to remain and grow in the pots or transferred to an outdoor garden bed.

Healthy, Happy Begonia Tubers in your Beds, On Your Patio and in Hanging Baskets

 Now that you have successfully started your begonias indoors and have moved them outside, growing healthy, happy begonias is relatively easy!  If you are reading this in late spring or early summer and missed out on the opportunity to start the tubers indoors, don’t fret. You can still grow healthy, happy begonias outdoors this summer; they may just take a little longer to bloom!  Once the begonia plants you started or tubers you are going to be plant are ready for outdoor growth, consider these 4 factors for healthy, happy begonia tubers:

  • Choose a location they can thrive in! Begonias thrive in semi-shade and do not do well in the hot midday sun. Strong winds may also damage tall begonia stems late in the season, consider finding a location where they are sheltered from these drying and damaging winds.
  • Hydration is important! Begonias dislike dry conditions. Be sure to provide them with ample water, especially in periods of hot weather. If you notice your begonias are looking a little droopy on hot, humid days give them a good healthy drink of water and watch the leaves and blooms perk up in a short amount of time.
  • Clean and maintain the plants for maximum energy! Remove all wilted leaves and flowers during the growing season to encourage flowering throughout the summer months. Not only does this help retain energy for the new blooms to come, but it will also help prevent fungal diseases from forming.
  • Fertilize for the most floriferous plants! During planting add a slow release fertilizer to the soil such as Espoma Bulb Tone to encourage healthy leaves, and blooms through the season. If planting begonias in pots or hanging baskets, combine your balanced slow release fertilizer with a liquid fertilizer according to package directions. Applying liquid fertilizer during summer once the bulbs are growing will encourage strong stems, leaves, healthy blooms and roots.

Overwintering Begonias

Begonia’s are sensitive to freezing temperatures and will not survive temperatures below 32 degrees. Gardeners in warm and temperate climates will not need to do anything special for the bulbs to survive over winter. The tubers will go dormant in winter in these warm climates and the flowers will return after their period of rest is over.

For gardeners in hardiness zones 3-7 who want to keep their begonias from year to year, they will need to follow steps to overwinter their begonia tubers. Before the first killing frost of the year, you will need to bring the tubers into a warm location that does not fall below 32 degrees.  If growing the tubers in pots or baskets, you can bring the whole pot inside to store for winter. You will want to keep the tubers on the dry side as they prepare for dormancy, and into their dormant period. In late winter and early spring, you may follow similar steps to starting your begonia tubers indoors to wake them up before you bring the pots outside for the season.

If your tubers are planted in the ground and you live in a cold climate where they need to be protected from freezing temperatures you will need to remove the tubers from the ground and store in a warm location. After removing the begonia tubers from the ground, remove the leaves and stems by cutting them back to near ground level with the tuber. Shake off any soil that is on the roots and tubers. Allow the tubers to dry off for a day before placing in storage. Once the tubers have been cleared of soil and moisture you may store them in a warm location in your home or basement. Place the tubers in a brown paper bag with wood shavings or vermiculite. Check the tubers weekly to ensure they are not drying out or rotting. If you notice the bulbs are becoming light, it means the tubers are drying out and you may want to spritz them with some water, allow the tubers to dry before placing them back in storage.  If the tubers seem to be soft, wet or moldy remove from storage to allow drying before placing back in storage. If storing over the winter does not work out for you, Holland Bulb Farms and Tulip World carry the largest begonias available with plenty of unique varieties to choose from!

New Year, New Begonias!

Pink Blush Scentiment BegoniaLast year I planted Pink Blush Scentiment Begonias in my owl planters, and they turned out quite nice! In other years, I have planted Pink Hanging Basket Begonias and Red Hanging Basket Begonias, because well, who doesn’t love beautiful rose-shaped blooms cascading from baskets at the entryway to their house. This year I may plant some Scarlet Begonias as a tribute to one of my favorite bands The Grateful Dead and their song Scarlet Begonias! Although I don’t have a plan quite yet for which begonias I am going to plant. I know I will certainly have some begonias in hanging baskets, in my owl planters, and perhaps a few other shaded locations throughout my yard this year!

Need Gardening Help?

If you need any help with gardening or if you have plant-related questions or concerns, feel free to reach out to Jenny San Filippo. She can provide you with the knowledge and tools needed to succeed with your next project!

Contact Jenny

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