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Copyright 2005, Board of Trustees, University
F0 0on i as
B. Tjia and R. J. Black
Florida Cooperative Extension Service .Institute of Food and Agricultural Sciences
University of Florida, Gainesville John T. Woeste, Dean for Extension
FIBROUS-ROOTED BEGONIAS FOR FLORIDA
B. Tjia and R. J. Black
Dept. of Ornamental Horticulture
University of Florida
Gainesville, FL 32611
If you like variety and a constant display of color throughout the season, you'll
love begonias. The begonia family contains more than 1200 species and hybrids
with an infinite selection of sizes, growth habits, foliage and flowers. The smallest
begonias may be only 2 inches (5 cm) tall with leaves smaller than a penny, while
giant begonias stand 6.5 feet (2 m) in height with leaves 2 feet (60 cm) long. Some
begonias creep and crawl, some grow like a tree, and some are bushy. Many resem-
ble other plants, with leaves like elm, palm, maple, ivy and other plants.
The begonia is chiefly of tropical origin. It was first discovered in Santo
Domingo in 1690 by Charles Plumier, who named the flower for his patron, Michel
Begon. The popular fibrous-rooted or wax begonia (Begonia semperflorens) origi-
nated in Brazil. Begonias are essentially classified according to the type of roots
they possess: (1) tuberous, (2) fibrous, and (3) rhizomatous. The tuberous begonias
are primarily propagated from tubers, whereas the fibrous-rooted begonias possess
fibrous roots and are further subdivided into the "cane stemmed" (e.g. angel wing
begonia), the "hairy stemmed" (e.g. Hirsute begonia) and the common "bush type"
begonias (e.g. wax begonia). The rhizomatous begonias (e.g. Rex begonia) possess
thick, root-like rhizomes which grow either erectly or horizontally.
The bushy fibrous-rooted begonias are most popular with homeowners. They are
frequently sold as house plants, holiday plants, or bedding plants in spring for
north Florida, and in fall and early spring in central and south Florida.
Since they bloom profusely, fibrous-rooted begonias are used during the winter
as pot plants to decorate windowsills and kitchen tables. Many of these may be set
in shady areas of the yard in late spring either in containers or in ground beds.
To be most effective in the landscape, begonias should be used in mass rather than
mixed with other annuals (Figure 1).
Formerly, fibrous-rooted begonias were mostly non-hybrid varieties, and these
old varieties did best in partial shade. However, through the recent concentrated
efforts of plant breeders here and abroad, many new varieties have been introduced
displaying a diversity of flower color, foliage color and growth habit. Today's
fibrous-rooted begonias require little maintenance, making them well adapted for
homeowners' use. Few other annuals can beat the fibrous-rooted begonias for hardi-
ness and continuous bloom throughout the summer season. Today's hybrids are not
restricted to a partial shade location; they can be grown in full sun as well. They
perform better, in fact, when planted in full sun. Under Florida conditions, the
fibrous-rooted begonias withstand drought and heat better than many annuals,
including the popular petunia. In addition, begonias will not grow out of bounds
and can be planted close together in a relatively small area, such as in a border
Begonias grow slower than other annuals making them suitable for use in
window boxes, flower boxes and hanging baskets. They are virtually insect free and
are resistant to pesticide injury. Begonias offer many variations in flower and
foliage color; green, bronze, and variegated foliage are available with a combination
of white, pink or red flowers.
Figures 1 (above) and 2 Well landscaped yards utilizing
Care and Culture
Begonias tend to grow somewhat larger if grown outdoors in a flower bed where
root growth is not restricted. In flower pots or planters, they usually do not grow
quite as large. Plants should ordinarily be placed 8-12 inches (20-30 cm) apart for
the best effect in the garden and somewhat closer in containers.
Begonia seedlings can be purchased in early spring, after danger of frost is past,
in north Florida and most anytime in the fall, winter and early spring in central and
south Florida, including the Keys. These can then be transplanted right away either
into one-gallon pots or into flower beds. It is easier and less expensive to transplant
them into pots and then move the pots to the permanent location in the yard.
Sink the pot into the soil until the top surface of the pot is at soil level. Mulch with
grass clippings, cypress bark or any other mulching material. Growing plants in pots
placed in the ground has the following advantages: (1) eliminates the expense of
adding large volumes of top soil to the flower beds; (2) plants can be grown in areas
having poor soils (in areas where the soil consists of thin marly materials overlying
limestone, such as Dade and Monroe Counties, begonias can be grown successfully
without too much dependence on the existing sand on marl); (3) less fertilizer is
needed although fertilization frequency may be increased; (4) nutrient pollution is
reduced, since leaching of fertilizers is virtually nil; (5) soil-borne insect and nema-
tode problems are minimized; (6) less watering is needed since a good organic soil
medium holds more moisture than marl or sandy soils; (7) excellent flowers can be
grown where commonly inferior plants have grown, especially around shrubbery
and trees; (8) reduces expenses since a good medium can be reused year after year;
(9) keeping your neighbors wondering why you have such a magical green thumb.
For best growth of begonias in flower beds, sandy Florida soils require some
amendments. Begonias thrive on light, slightly acid, well-drained organic soil. To
improve the soil structure and increase the water holding capacity, add a substantial
amount (up to 50%) of organic matter such as peat moss, leaf mold or well-rotted
manure. Begonias are not heavy feeders, so fertilizer should be applied sparingly. If
well-rotted manure is used to amend the soil, the addition of fertilizer is not neces-
sary, since manure contains some mineral elements needed for the plants.
The rate of fertilizer application is based on the nitrogen that is present in the
fertilizer formulation. The recommended fertilization rate for begonias grown in
beds is the same as for annuals. Generally, for a fertilizer which contains 5% nitro-
gen the recommended rate for begonias is 2 Ibs. (908 g) for each 100 sq. ft.
(9.3 m2). When a fertilizer containing 10% nitrogen is used instead, since it is twice
as concentrated as the 5% formulation, the rate of application should be 1 lb.
(454 g) per 100 sq. ft. (9.3 m2) to give the equivalent of 2 Ibs. per 100 sq. ft. for
the 5% nitrogen containing fertilizer. If a 20% formulation is used, obviously the
rate used should be lb. (227 g) per 100 sq. ft. (9.3 m2).
If you know how much to apply based on the nitrogen percentage, many kinds
of fertilizers can be used without dependence on only one formulation of fertilizer
that may not be available in your locality.
When begonias are grown in pots, the fertilizer used should be 4 the rate recom-
mended for plants grown in ground beds. For instance, when a 5% nitrogen con-
taining fertilizer is used, the rate for 100 sq. ft. (9.3 m2) should be /2 Ib. (250 g),
and this amount should be divided equally among the number of pots occupying
100 sq. ft. (9.3 m2) of area.
As mentioned previously, begonias are not heavy feeders and the root systems
are somewhat restricted for pot grown plants. For these reasons, the rate of fertil-
izer should be further reduced to half the recommended rate for soil grown plants
but, the frequency of fertilizer application should be increased, such as biweekly
rather than monthly. Thus, 4 Ib. (125 g) of 5% nitrogen containing fertilizer
applied biweekly should give the best results.
Figure 3 A large flowered, pure white begonia-"Glamour White."
Most fibrous-rooted begonias, with the exception of the double flowered varie-
ties, are propagated from seed. The double flowered varieties are sterile and have to
be propagated vegetatively.
Purchasing your own seeds and germinating them is not a good practice, since
good begonia seeds are expensive and they are smaller than petunia seeds. There are
approximately 2,000,000 seeds per ounce, and unless you have specialized germi-
nating chambers, the average homeowner will not be able to germinate begonia
seeds to his or her satisfaction.
The fibrous-rooted double strain is somewhat of a novelty, producing about
50% doubles, if sown from seed. They make excellent pot plants, but are not
recommended for flower beds. There are three varieties available: Christmas Candle,
White Christmas and Jewelite.
One of the recent introductions is a group of F1 hybrids called Caravelle.
These begonias have large leaves and large red, pink, or rose colored flowers.
Figure 4 A large, bicolored white-pink edged begonia- "Glamour
The hybrid, single flowered types (Figures 3 and 4) are commonly grown from
seed. These hybrids can also be propagated vegetatively, but there are several pro-
blems. Cuttings taken from plants grown in the landscape all summer may be in-
fested with diseases and/or insects. Also, plants propagated from cuttings will not
branch freely resulting in single stem plants. Flowers develop from axils at nodes
(Figure 5). When flowers are produced from the axils no other vegetative growing
points are present. Therefore, when flower stems peduncless) abort from the nodes
no branches will develop. Most fibrous-rooted begonias develop flower clusters at
each axil. Consequently, cuttings taken from flowering mother plants will always
result in single stem plants. It is, therefore, beneficial to use plants started by com-
mercial growers from seed free of disease and insects rather than from cuttings.
Young plants from seed will develop branches profusely, thus making them worth
the extra expense.
Figure 5 Parts of the begonia stem: a) Terminal growing point (apical
meristem), b) Flower in leaf axil at a node, c) Node from which a flow-
er stem pedunclee) has aborted. No lateral branches will develop at this
Begonias are often grown and sold in small plastic containers called "cell paks"
(Figure 6). When begonias are purchased in cell paks, they should be planted as
soon as possible. If the plants remain in the cell paks for an extended period of
time, they will become hardened and their subsequent growth after transplanting
will be impaired. Begonia plants can also be purchased in small peat containers
(Figure 7). These peat containers can be planted without removing the plastic net-
ting that surrounds the peat ball.
The best performing begonia varieties adapted to Florida are listed in the follow-
ing table according to light requirement, plant height, and growth habit. Groups or
series in the same height category have similar growth habits and differ primarily in
flower and/or leaf color.
Figure 6 A red flowered cultivar, "Scarlet Sensation," in small plastic cell
Figure 7 Commercial production of begonias in peat containers. (Insert in
upper left shows an individual peat container.)
F1 Hybrid Begonias for Semi-Shaded
and Full Sun Areas
Grows 10 to 14 inches (25 to 35 cm) in pots and 14 to 16 inches (35 to 40 cm)
Danica Bronze Rose Rich rose color Bushy, dark
leaved plants with large blooms
unlike some large-flowered strains.
Withered flowers do not detract
from plant beauty.
Cinderella Bronze Rose Suitable to be grown in pots.
series White Produces 50% extra large flow-
Pink ers with a large, bright golden
Mixed center. Leaves are somewhat larger
than the regular strain.
Grows 4 to 8 inches (10 to 20 cm) in pots and 8 to 10 inches (20 to 25 cm) outdoors.
Name Color Color Remarks
Bright pink. Excellent for pots
and beds. The red cultivar is a
clear red. Both the pink and red
cultivars bloom profusely.
Light scarlet with a white
center. Very compact and free
Excellent mixture of soft shades
of rose, red, pink and white. While
foliage is predominantly green,
about 20% of the plants have
Grows to 3 to 5 inches (7.5 to 12.5 cm) in pots and 6 to 8 inches (15 to 20 cm) in beds.
Name Color Color Remarks
Early and free flowering, luminous
Pure white flowers.
Very large flowers, bloom when
plants are 3 inches (8 cm) high.
Excellent free flowering bedding
plant in pots and beds. Flowers
are 2 inches (5 cm) across.
Slightly smaller blooms than the
sisters, blooms when 3 inches
(8 cm) high.
Larger flowers than the stan-
dard varieties, such as scarletta,
with the same small leaves, but
not as compact habit.
Earliest large flowered fibrous
Flowers contrast well with
bronze foliage. Makes showy flower
beds compact and uniform.
Scarlet orange. Outstanding for
its deep, waxy, bronze foliage.
Performs equally well in pots
or beds outdoors.
plants. Sun resistant.
Green White with
Uniform and free flowering.
Uniform and free flowering,
Pure white florets, borne freely
above dark bronze foliage.
Regular Inbred Begonias
for Shady Locations Only
Grows to 4 to 6 inches (10 to 15 cm) in pots and 6 to 8 inches (15 to 20 cm)
Bicolor flowers, white with pink
Bicolor Glistening white with each petal
edge tinged salmon pink. Early
blooming, free flowering, compact
Rose Rich rose flowers, large and com-
pact. Resists disease and adverse
White Dwarf, pure white flowers, weather
Bright red Color does not soften as florets
mature. Earlier and much larger
flowered than most red flowered
Bright All plants bloom freely, at once and
Scarlet very early.
Snowbank Green White
Carmen Bronze Red
Indian maid Bronze Pink
Pests and Diseases*
Begonias are not attacked by many insects. The major pests that may infest
begonias are snails and slugs, but these can be controlled with an appropriate snail
There are some fungus organisms that may infest begonias. The major ones that
usually present problems are:
Powdery Mildew The symptoms are white, powdery spots on upper and lower leaf
surfaces. The fungus survives on the living tissue. The disease is
prevalent when temperatures are somewhat low and plants are
grown in heavy shade.
Root and Stem Rot Caused by Pythium Sp. Plants are usually stunted and un-
thrifty. Root system is small and discolored (brown); stems be-
come water-soaked, discolored, and collapse. The disease is favored
by frequent rain or over watering.
Botrytis blight (Botrytis cinerea) Symptoms occur as a soft brown rot of leaves,
stem, and flowers. Woolly, gray fungus spores form on decayed
tissues. Fungus is common on plants weakened by root rot.
Botrytis may also start in powdery mildew spots and sunburned
tissues. The disease is favored by high relative humidity and low
*For information on fungicides and insecticides that can be used on begonias,
contact your local County Extension Office.
This public document was printed at an annual cost of $456.40,
or 0.09 cents per copy, to inform interested residents on growing
begonias in Florida.
Single copies are free to residents of Florida and may be ob-
tained from the County Extension Office. Bulk rates are
available upon request. Please submit details of the request to
C. M. Hinton, Publication Distribution Center, IFAS Building
664, University of Florida, Galnesvllle, Florida 32611.
COOPERATIVE EXTENSION WORK IN AGRICULTURE AND HOME ECONOMICS
(Acts of May 8 and June 30, 1914)
Cooperative Extension Service, IFAS, University of Florida
and United States Department of Agriculture, Cooperating
K. R. Tefertiller, Director