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Tuberous Begonias for Every Garden

by Dr. Leonard Perry, Extension Professor,University of Vermont    

If you are looking for a colorful, attractive flower to grace your garden, try the tuberous begonia. It is easy to grow, does well
in the shade, needs moderate care, and will reward you with a lovely display of blooms all summer long.

Tuberous begonias come in shades of white, pink, red, yellow, orange, and salmon, as well as bi-colors. If they have a darker
edge to the petals, they are called "picotee." Double flowers are male, and single flowers female. The large flowers are usually
double and may be six inches or more in diameter. Plants generally grow 12 to 18 inches tall.

Depending on the variety, plants may have camellia, ruffled camellia, or rosebud type flowers. The hanging basket has smaller,
more numerous flowers than the more erect types.

Nonstop begonias, which were first developed in Germany, are a popular series. They are so named because if given some
light during the night during winter months (indoors or in a greenhouse, of course), they will bloom nonstop.

Many people don't realize that begonia flowers can be eaten! The lemony sour flavor goes well with fruit salad, salads, yogurt,
or ice cream. Just make sure if you are going to eat flowers, you don't use any pesticides on the plant.

Tuberous begonias do best in a location that has partial to full shade and light, rich, well-drained soil. However, they also make
excellent patio plants in containers.

Prepare the site by incorporating organic matter, such as peat moss or compost, into the upper eight to ten inches of the soil to
improve plant performance. Add fertilizer at the rates recommended by a soil test, or feed every two weeks with a general
purpose liquid fertilizer. Use half strength when the plants are young and just sprouting. You may also use a slow or controlled
release fertilizer in the final beds or pots.

Purchase only high quality, firm tubers. Tubers can be started early indoors one month before the frost-free date for your area
in flats or pots filled with a 50:50 mixture of moist peat moss and perlite. The depressed side of the tuber should be facing up.
The tubers should be sprouted in the dark at 70 degrees F.

As soon as shoots develop, cover the tubers with more peat moss, and move to a bright location such as a sunny window. The
young plants should not be transplanted outdoors until all danger of frost has passed.

When planting, place the tubers just slightly below the soil line as they rot easily when planted too deep. A minimum 18-inch
spacing is recommended to allow the plants to fill out properly. After planting, do not cultivate around the root system or
fibrous roots will be damaged. Since the stems are quite brittle, they often need staking, especially in windy areas.

Plants should be watered when the soil begins to dry. The tubers will rot if they are overwatered. Try to water in the morning if
possible so that any moisture that gets on the foliage will have time to dry before evening. Wet foliage increases the chance of
disease.

Pick flowers off as the edges turn brown to prevent them from rotting and starting disease. If plants are dry and stressed and
the leaves turn brown, the cause may be too much sun, too much heat, or too little water. If plants are leggy, this means that
they are getting too little light. White growth on leaves is powdery mildew disease. Fungicides can be used, but wider spacing
and more air circulation may be all that is needed.

After the first fall frost, dig the tubers and remove the foliage. Dry the tubers for a few days, and store them overwinter by
placing them in dry peat moss or sawdust in a paper bag at about 50 degrees F.


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University of Vermont