Weekly Express-News Article
By Calvin R. Finch, PhD, SAWS Water Resources Director, and Horticulturist
Saturday, June 30, 2007
Bouganvillea is the premiere patio plant for full sun in San
Antonio. It is very colorful, relatively easy to grow and very
heat tolerant. Grow bouganvillea in full sun at the hottest location
in your landscape.
Bouganvillea is one of the few plants that is actually easier
to grow in a container than in the ground. It is hard to believe,
but our soil has too many nutrients for good bougainvillea. I
should rephrase that, the plants grow great, but they do not bloom.
You may have experienced the phenomenon when your bougainvillea
entered the soil through the drain hole or through a crack in
the pot. The leaves grow to three or four inches and the vine
adds six-eight inches of growth each day, but without the benefit
of the colorful bracts we call flowers.
The keys to good bougainvillea bloom are a contained root system,
a soil that dries between waterings, reasonable fertilization,
some pruning and full sun. It is true, bougainvilleas bloom best
when the roots are restricted. Plants in containers only begin
their bloom period after the roots have filled the container.
Repotting bouganvillea is less of an issue than it is for other
plants, they will perform well for years without repotting.
Bouganvillea seem to bloom best when the top is about 1.5 times
as large as the roots. A twelve inch pot supports a top of about
18 inches around and high. Prune off the tips of the shoots to
maintain that size. The tip pruning technique also results in
side branching so there are more blooms. The blooms occur at the
end of the branches. Tip pruning means pulling of one inch or
less of branch every two weeks.
Irrigate bougainvillea only when the soil has dried to two inches.
Many gardeners wait until the plant wilts before they water. Water
enough to have moisture emerge from the drain hole. Fertilize
bougainvillea with a soluble fertilizer such as Miracle Gro, Peters,
or Rapid Gro every other time you water. The other option is to
use granular hibiscus food. It seems to work very well and is
easier to use than mixing up the soluble fertilizer.
Bouganvillea are not usually bothered by insects or diseases.
Control the occasional caterpillar attack with Bt or Spinosad.
The plants are cyclical bloomers. Expect six week of color followed
by an equal period of green. They are very sensitive to cold.
Blooming stops when temperatures fall into the low 50’s
and freeze damage can occur in the high 30’s. The good new
is that bougainvillea are easy to store for the winter. They do
not need light so you can prune them back and stack them up in
the garage or spare room from November until April.
There are a number of bougainvillea selections. The most popular
selection is Barbara Karst. It has a red (dark pink) bloom and
is a heavy bloomer. The lavenders, darker reds, off whites and
yellows have appeal, but do not bloom as heavy. There are also
doubles and variegated selections. The doubles are very attractive,
but hold on to spent blooms. They look best if they are groomed
every few days. The single bloomers like Barbara Karst drop spent
flowers without requiring removing them.