Full to partial
sun is best (a south, east, or west exposure). C. splendens and
C. quadriloculare are winter bloomers and are sensitive to the
decreasing day length. Starting in early fall, grow them in an
area that doesn’t have artificial light after sunset, which promotes
flower formation. If they fail to bloom, it’s probably due to
a disruption of the shortening day lengths
Temperature:
Maintain
temperatures above 60 degrees for active growth, as they perform
better on the warm side.
Humidity:
Preferably 50%
or higher; however, they will tolerate low levels with no harm.
Watering:
Bring soil to a
state of visual dryness between waterings. In clay pots under
warm conditions, they can have a high demand for water and, thus,
should be checked once a day for dryness. Try to prevent them
from wilting severely; however, a slight wilt shouldn’t hurt.
Fertilizer:
Fertilize with a
soluble fertilizer - ½ tsp./gallon every two weeks or, under high
light conditions, once a week. They are rapid growers and heavy
feeders under high light. Reduce or restrict fertilizer in
winter under low light.
Pruning:
Over a growing
season, they can become large plants that won’t fit well in the
indoor growing space. Pruning should be done after the blooming
cycle is completed. Winter blooming varieties need their last pruning
in early to mid summer, bringing the plants into full growth by early
fall whne they sense the decreasing day light. They can be pruned
severely, from which they quickly re-sprout.
Insects and
Disease:
Clerodendrums
have a susceptibility to spider mites, white flies and aphids.
Periodic checking of the undersides of the leaves is important to
maintain control. Spray the plants immediately when insects are
first noticed. Be sure to keep infected plants away from healthy
plants.
Comments:
Clerodendrums
are both vines and shrubs that are vigorous and easy to grow.
Some are summer blooming or respond to high light and long days to
induce flowers; others are short day length bloomers. C.
thomsoniae flowers in the spring and summer but needs a winter
dormancy to flower well. The restriction of water and cool
temperatures along with shortening day length will do the trick.
