It is sometimes seen as Million Bells, although this is a
registered brand name of one of the early introductions of this
flower. Or, you may see this called “trailing petunia” from its
small, petunia-type flowers. But it is not a petunia, although
related to them and in the same nightshade (Solanaceae) family.
Calibrachoa originally comes from the same part of South America
as petunias— from southern Brazil to Peru and Chile— where it is
an evergreen, sprawling and short-lived perennial. In this country
it is only perennial in USDA hardiness zone 9 and warmer—along the
Gulf coast, central Florida, and coastal California. It was named
for the 19th-century Mexican botanist Antonio de la Cal y Bracho.
Breeders have crossed petunias with calibrachoa to form a hybrid
Calibrachoa has a less dense habit, much smaller plant overall,
and smaller leaves and flowers than petunias. It generally grows
three to nine inches tall and up to 20 inches wide. Since it has
a very open habit, weeds are prone to grow among stems if you
don’t use a weed fabric and mulch under plant stems.
Grow calibrachoa as you would petunias, in at least six to eight
hours of direct sun a day. It will tolerate less, but won’t bloom
as well. Growing soil should have a neutral pH around 7.0
—neither too acidic nor alkaline. Their original habitats are
cliff edges and rocky scree.
Plant in a well-drained soil, and allow soil to dry between
watering plants (obviously a problem in rainy weather).
Established plants will tolerate drought, but repeated drying out
makes plants more woody and less vigorous. Overly wet soils often
result in root rot diseases.
Fertilize regularly, according to label directions on product of
your choice. It likes lots of nitrogen. Calibrachoa is a
low-maintenance plant, as it really attracts no significant pests
or diseases. Their main growth problems may come from improper
soils and watering, making them more suitable often for containers
than ground beds and garden soils. Cool soils during a cool
northern summer may affect their ability to absorb certain
nutrients like iron.
There is one series that you can grow from seeds—Kabloom— with
the rest of the many varieties only available for sale as plants
grown from cuttings. If you want to try starting these seeds,
they prefer a soil temperature of around 70 degrees (F). It takes
10 to 14 days for germination, and eight to ten weeks to grow
plants large enough to plant outside.
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