How to Grow Begonias from Tubers
February through March is exactly the right time to start Tuberous Begonias! Tuberous Begonias are by far the longest blooming of the summer flowering bulbs. Truly gorgeous, large vibrant blooms on top of plants that grow about 10-15 inches in height. They bloom from June until frost and if you have a good location for them they are fairly easy to grow.
They need a shady, morning sun or filtered sun location that is not cold and wet. They can be grown in containers or the garden and are equally beautiful either way. Start Tuberous Begonias from February through March. They are the first bulbs to come into garden centers in the new year before the dahlias, lilies, gladiolus and other summer flowering bulbs are available.
Choose from colours such as white, yellow, orange, red and pink; trailing which are great for hanging baskets or upright plants. The tubers are disc-like in shape with a concave side and a rounded side.
Using individual four-inch size pots, plant tubers concave side (dish side) up into sterilized potting soil very shallowly with no more than a quarter of an inch of soil on top of the tuber. You may be able to see tiny pink buds where the new growth is starting. Place in a well-lit location such as a windowsill with minimum temperatures of 65F/18C degrees. Water to keep moist but not wet always watering into a saucer from the bottom. An all-purpose liquid fertilizer such as 20-20-20 or 15-30-15 should be started after the tubers are well in leaf and can be continued right through the summer.
After the first week in May, you can begin hardening off your begonias the same way you harden your other bedding plants off. Set them outside in the morning sun and bringing them in at night for a few days. Then for a day or two set them outside close to the house all day and overnight. Our weather can still be a little cool at this time, so you'll have to be mindful. Putting them out when it is still too cold can set them back quite a bit, discolour the leaves or simply kill them. If the weather looks bad, play it safe and wait. Planting your begonias out into the garden after the middle of May is usually quite safe.
When you plant them you will notice that the pointy leaves mostly all point in one direction. The flowers tend to mostly point in that direction as well, so in containers plant them with these pointed leaves radiating out from the center for the best effect. When planting in the garden plant so that the points and later flowers will mostly be facing you. Enjoy your begonias all summer, watering and fertilizing as necessary. You can pinch the single 'male' flowers off if you wish to increase the size of the double flowers. Either way, they are simply stunning.
At the very end of the season when we are approaching our first frosts withhold watering for a few weeks. Then lift the tubers and let the plants die down naturally in a frost-free location. Clean the old leaves and dirt off the tubers and store in peat moss in a frost-free location until the next February when you can bring them out and pot them up for many seasons to come.
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