Spring must be on its way because the tuberous begonia tubers arrived at the garden centre this week.
Of all the shade-loving plants, the tuberous begonia is one of the favourites. They can be planted in flowerbeds, but are also beautiful in containers, either on their own or mixed with other shade-loving plants such as fuchsias, impatiens, ivy, bacopa, creeping charlie, silver nettle, lobelia, etc.
There are many different types and varieties of tuberous begonias that come in a wide range of
colour.
There are many forms and colours of the double flowering types that come in shades of red, orange, pink, yellow and white. Others such as frimbiata have double flowers with a ruffled edge similar to a carnation.
Crispa marginata also has a two-toned flower but the flower is a single instead of a double. All of these do very well in containers.
If you are buying tubers for the first time look for a large tuber that is firm with no visible signs of
damage or disease.
Soil should be light and airy with good drainage, all important factors in growing healthy tuberous begonias.
The last item needed in growing tubers is the container to start the tuber in.
We like to use four-inch peat pots as these are easy to transplant out at a later date when it is time to place the plants outside. The peat pot can be directly placed in the soil as it breaks down, causing less stress on the plants roots.
To plant the tuber, fill the peat pot with moistened potting soil then place the tuber on top of the soil with the hollow side facing up as this is the top side of the tuber.
Gently press the tuber into the soil and then cover it lightly with an inch of soil.
Water the soil surrounding the tuber being careful not to get any water in the hollow part of the
tuber as this can cause it to rot.
Place the planted tuber in a tray and then put it on a well lit window sill or under a grow light where the temperature is 17 to 20 Celsius.
To help speed up the process a plastic dome can be placed over the pot and when the pink eyes begin to show the dome can be removed.
While waiting for the tuber to show signs of growth, only water the soil when it feels dry.
When it begins to grow, increase the water (try not to get the foliage wet) give it lots of light and begin to fertilize with 10-52-10 which is a good plant start fertilizer. When the plant is established switch to a balanced fertilize such as 20-20-20 and then lastly fertilizer with a flowering plant fertilizer 12-36-12.
Tuberous begonias are shade-loving plants, so when the sun gets hotter you will want to keep the growing plants away from direct midday sun. In the beginning of May the plants can be hardened off by placing them outdoors in a shaded area during the day and brought in at night. After all risk of frost has passed they can be
transplanted outdoors.
Begonias can not take any frost, so if there is frost warning be sure to give them extra protection by covering them up or bringing the containers in.
If cared for properly, they will bloom throughout the summer and into early fall until the frost gets them. The tubers can then be brought indoors and stored, and then re-planted in February for another season of
enjoyment.
