The Tuberous Begonia In Colorado

If you love using containers in your garden or if you are strictly a container gardener, you will appreciate knowing that the tuberous Begonia in Colorado does very well. I have a large covered front porch. My property also includes a lot of trees. As a result, I have quite a bit of shade in my garden. I need a few flowers that do well on my porch and under my shade trees. Tuberous begonia is one of my go to plants. Here is one that was growing in my garden in 2011.

But here is the problem. To buy a flowering Begonia at a nursery is going to set you back about $6.99 for each plant. Yikes! But there is a way around this high cost. Let me show you how.

While I can’t do $6.99 per plant, I can buy the tubers at a much lower cost. And if I plan ahead by planting them in dirt in March, I can watch them grow throughout the season and overwinter the tubers, using them again next season. When you can get 6-8 tubers for $7-8, this is far more economical than than $6.99 per plant.  Here are my simple instructions on growing the tuberous Begonia in Colorado.

The Tuberous Begonia In Colorado 


  • In mid March, purchase tuberous begonias at your local nursery or big box store. If you see them sold in a bag or box these are tuberous begonias. Why March? This will give the time to start growing so that you have flowers by early June or so.
  • Moisten potting mix.
  • Using a flat (typically used for holding seedling trays, but one without drainage holes), place tubers 2-4 inches apart on a layer of moistened potting mix. The potting mix should be about 2 inches deep. Some people put a layer of pebbles/sand in the tray to aid in drainage. I don’t bother with that because I don’t over water them. I keep the soil moist but not soggy.

    • When you place the tuber onto the soil, make sure the concave side is up and the hairy smoother side is down. If the tuber isn’t as concave, the bumpy side should  be what is up.

Tuberous Begonia: bottom side (notice the “hairs”)

Tuberous Begonia Right Side Up

    • Cover the tubers with a 1/2 inch more of soil and water lightly. It will feel as if you aren’t putting enough soil on top. You are doing it well if you still kind of see the top of the bulb.
    • Cover the tray with some plastic wrap or dome cover, keeping it on until you see sign of growth.
    • Place the tray in a bright window, but not direct sun. If you use grow lights indoors to start seedlings, it is not necessary to use grow lights for the tuberous begonia in Colorado. This is where I finished and placed my two flats of begonias on the date I published this post (March 8th).

See the two covered flats? Those contain newly planted begonia tubers. I’ll leave the lid on until I see signs of growth.

  • When the plant is 2-4 inches tall, re-pot into at least 4-6 inch pots. Or you may directly transfer them to larger pots or directly into outside garden if the threat of frost is past. Don’t put them outside too soon as they are very frost sensitive. I will plant my begonias into 4 inch pots for those that I want to go into a very large pot later with other plants. But typically I will use 8-10 inch pots, leaving these pots indoors until threat of frost is surely over, and then placing these pots in a collection on my front porch.

  • Throughout the summer, keep the pots moistened but not soggy. Do not place begonias in overly deep shade. They like bright indirect light, but not direct sun. Fertlize your begonias using a balanced fertilizer (balance between the three numbers you see on the side of the fertilizer container). I like to use 20-20-20.
  • The only disease that really gets to begonias is powdery mildew. Thankfully in Colorado we don’t have that problem too often. But if you see it, use a fungicide (preferably organic) to keep it at bay.
  • Allow your begonias to grow right up until frost as this strengthens the tubers. But do bring them indoors once frost is threatening.

  • If you have the begonias in pots, bring the entire pot indoors and stop watering them. Let them dry out in the soil. You can leave them in the pot over winter if you have room. Otherwise, dig them up and store them in dry peat moss.
  • If your begonias are in the ground (which I don’t do because this is a pain), dig the begonias up, being careful with the roots. Place them on a flat and bring inside to dry out. Then store them in bags of dry peat moss.
  • Repeat this whole process beginning in late winter in the next season.

One more picture…this one from my front porch.


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