Tuberous Begonias are a cool climate plant, not
sub-tropical.
People grow them well in Sydney, Perth and south of these.
If you are unsure, it is best to try cheaper non-stops first, then progress to more showy
large flowered plants.
Growing Tuberous Begonias is within the reach of most
people, but you must get three basic factors right.
The three basic factors are position,
potting mix and watering.
Choose a place where plants like ferns, fuchsias, hostas
or cymbidiums grow.
Give them good light, not direct sun (shade cloth ideal).
Not too much wind.
Not indoors – Tuberous Begonias need cool nights.
Suggest sunroom, conservatory, fernery, porch, greenhouse, protected garden
position.
This will make the difference between a nice plant and a
great plant.
Use a quality open mix with lots of air filled porosity.
We use and recommend perlite in the potting mix at about 10%.
Use a slow release fertilizer.
Begonias just love liquid organic fertilizer, such as seaweed extract or fish
emulsion.
Watering is critically important.
Watering incorrectly is
the most common cause of poor results or loss of tubers.
Watering should match the stage in the growth cycle of Tuberous Begonias.
Tuber starting or shooting stage, usually about
August or September.
Keep pots evenly moist by giving a light sprinkle of
water when the surface of the potting mix begins to dry.
Active growth stage, usually about October to May.
Pot should nearly dry between waterings. Water the pot thoroughly when the
surface of the potting mix completely dries.
Dormancy stage, from about early June to August.
Stop watering completely. Remove from access to rain and keep pots off the
ground (bare earth or lawn).
Seed propagation is done in spring. Do not cover the very fine, dust like seed. Keep it moist and humid.
Dividing tubers when they are dormant is never recommended by professional growers. Cut surfaces can allow rot to set in right away or years later.
Taking cuttings is easiest and recommended way:
When tuber sprouts more than one stem, keep one and use
the others for cuttings.
Wait till additional stem reaches about 7-12cm in height.
Take the stem firmly but gently from near it’s base, close
to the tuber.
Wiggle the stem from side to side, like loosening a tooth.
When the stem is really loose, pull it away from the
tuber.
Strike the cutting like other cuttings, use a hormone if
you like.
Do not allow the new plant to flower the first year, next
year’s plant will be a full sized begonia with full sized flowers.
Most common problem are tuber rots.
Caused by fungal or
bacterial infection.
Occur when plants are over watered or when kept moist
while dormant.
Very important during active growth stage not to water
until potting mix surface dries out.
Caterpillars can attack the leaves, use pyrethrum or
similar.
Powdery mildew looks like powdery white spots on the
leaves. Use a good fungicide with a wetting agent.