of Rhode Island GreenShare Factsheets
For African Violets
African violet (Saintpaulia ionantha) can be one of the most
satisfying flowering houseplants. It is a low, compact plant with
attractive dark green, thick, hairy leaves. The violet-like flowers
are borne in small panicles just above the foliage. Cultivars are
available with pink, fuschia and white flowers, as well as the more
traditional shades of blue-violet. Newer violets include cultivars
with semi-double or double rows of petals. Bi-colored flowers and
those with a contrasting border are popular. Trailing cultivars
and miniatures are also available. Plants kept in good condition
flower almost continuously.
A soil mixture composed of about 2 parts fertile loam, 1 part leaf
mold or peat and 1 part sand or perlite is recommended for growing
African violets. The soil must be porous to allow surplus water
to pass through readily. Most violets are now grown in a pasteurized
soilless mix--a good soilless mix is made up of 3 parts sphagnum
peat moss, 2 parts vermiculite and 1 part perlite, with some lime
added to balance the acidity of the peat moss. Compost, good garden
soil or loam can be used for up to half of the total mix, with the
other half vermiculite and/or perlite. A good growing medium should
contain 50 percent matter, 25 percent air and 25 percent water.
When potting African violets, take care to set the plant so that
the crown is just above the surface and the soil is firmly pressed
around it. Emphasis in planting should be on good soil drainage,
as any free water on the surface may cause decay at the crown or
at the bases of the leaf stalks. A saturated soil mix also leads
to unthrifty top growth and root rots. A layer of coarse gravel
at the bottom of the container will not improve drainage.
Store-bought potting mixes are pasteurized. If using a homemade
potting mix, it should be pasteurized and the pots disinfected before
planting. Place a 4-inch layer of the mix in a flat pan and wet
it slightly. Cover the pan with aluminum foil and seal the edges.
Preheat an oven to 180 to 200 degrees F. Place the soil in the oven
and hold it at that temperature for at least 30 minutes before removing
it to cool. When reusing pots, wash them thoroughly and then soak
them for 30 minutes in a solution of 1 part household chlorine bleach
in 9 parts water. Rinse the pots until all traces of chlorine are
violets about once a year, or when the leafless portion of the stem
is about 1 to 1 1/2 inches long. Gently remove the plant from the
pot with a paring knife. Remove all lateral crowns, leaving only
the center crown. Trim off one or two rows of leaves, leaving a
wheel of leaves around the crown. With the paring knife, scrape
the neck as you would a carrot until all the brown plant material
is removed and the neck is firm and green. Break or cut off the
bottom half of the root. Have a clean pot ready for the pruned violet.
Gently firm in new soil around the plant and water well. The pot
should be one-third the diameter of the plant; a 4-inch pot is usually
usual method of propagation is by leaf cuttings during the spring.
Cut off mature leaves with one inch of their stalks. Firmly plant
the stalks into sand or vermiculite with most of the leaf blades
exposed. Thoroughly water the sand. In greenhouses, the benches
of cuttings are usually covered with light muslin or glass to keep
the air moist. In the window garden, a few cuttings can be covered
with a glass jar or plastic. In two to six months, young plants
start from the bases of the stalks, which are ready to be potted
after they have formed two or three small leaves.
African violets adjust well to the warm temperatures and dry air
of homes. Although they require good light, direct sunlight is not
necessary. Windows facing north or east provide favorable light
conditions and are preferable to those exposed to midday and afternoon
sunshine during summer. The sunnier, warmer windows are better in
temperatures for African violets are about 60 degrees F at night
and up to 80 to 85 degrees F during the day. The plants become stunted
at cool temperatures and are slow to recover, even when moved into
a warm place. Plants are especially susceptible to rot in hot weather
(over 85 degrees F).
The soil must be kept moist at all times, the foliage should be
kept dry. Drops of water on the leaves cause disfiguring light-colored
spots or rings. Proper watering can be simplified by keeping the
pots in watertight saucers or bowls into which a little water is
poured every few days. A wick extending through the drainage hole
into a saucer of water may also be used. Another effective method
is to submerge the pots in peat or sphagnum moss within in a larger
container and apply water to the peat or moss as needed to keep
the soil moist in the pots. In either of these methods, water moves
from the saucer or peat by diffusion through the hole in the bottom
of the pot and into the soil ball.
of the major problems associated with African violet care is excessive
watering, which can lead to root or crown rot. Root and crown
rot caused by the fungus Pythium ultimum may occur on overwatered
plants. Plants of all ages can be affected. The crown and roots
of these infected plants turn dark and soft and the leaves usually
wilt. Infected plants can be lifted easily from the soil. This disease
is not a problem when plants are grown in a pasteurized soil mixture
in a container that allows for proper drainage. Destroy badly diseased
plants, and thoroughly clean and disinfect their containers before
reuse. Highly prized plants can sometimes be saved if the crown
is not badly decayed. Remove the rotted portion of the crown well
above the line of decay and reroot the plant in sterile medium.
rot begins as an orange-brown or rust-colored lesion where the
petiole touches the rim of the pot or where it contacts the soil.
This is aggravated by the accumulation of fertilizer salts on the
rim of the porous pot or on the soil surface. An aluminum foil collar
on the rim of the pot and flushing the soil occasionally with heavy
watering will prevent this problem.
unsightly yellow or white ring and line patterns that occasionally
appear on the leaves are thought to be caused by a sudden chilling
of the leaves by cold water or by the sun shining on wet leaves.
This condition is known as ring spot or chlorosis, and can
be avoided by carefully watering the plants from below with water
slightly warmer than air temperature.
violets infested with root-knot nematodes are stunted and
weakened. Galls form on the roots, and the crown and leaves become
thickened and distorted. Blisterlike galls also develop on the leaves.
Destroy all infested plants, sterilize their containers, and propagate
new plants only from nematode-free plants.
leaves of plants grown under greenhouse conditions may become infected
by the fungus Botrytis cinerea. Botrytis blight first
appears as small, water-soaked lesions on the underside of the leaf.
These lesions enlarge until much of the leaf turns brown to black.
Flowers may be similarly affected. High humidity, poor air circulation
and low light intensity contribute to the development of this disease.
Spores of the pathogen are spread by direct contact of leaves. Spacing
the plants so that the leaves of adjacent plants will not touch
reduces spreading to healthy plants. Since infection by Botrytis
often follows mite injury, controlling these pests aids in controlling
the disease. The application of a foliar fungicide may be needed
to control severe outbreaks.
mildew is a light grey, powdery substance on the stems and petioles.
This shortens the life of blooms and makes the violet unthrifty.
Mildew grows in cool, moist, stagnant air. The best cure is air
circulation--a small fan moving the air in the room will help prevent
powdery mildew. See GreenShare Factsheet
on powdery mildew for more information and control recommendations.
and mites occasionally damage the foliage and flowers of African
violets. Cyclamen mites feed in the plant crown, causing
young leaves and new growth to be stunted, twisted, discolored,
and brittle. When infestations are heavy, leaf hairs become matted
and flower buds fail to open. Isolate infested plants and be careful
while handling them so you do not accidentally transfer mites from
one plant to another.
are small, soft-bodied insects that occur in white, cotton clusters
on the surfaces of leaves, on leaf petioles, and near the bases
of leaf stems. They injure plants by sucking plant juices, causing
stunting and distortion of the leaves. Mealybugs also excrete a
shiny, sticky substance called honeydew that is highly attractive
to ants and also supports unsightly growths of a dark sooty mold.
Heavy mealybug infestations may cause leaves and plants to wither
and die. Mealybugs can often be eliminated by spraying plants with
a jet of lukewarm water or by removing them with a cotton swab dipped
in alcohol. Ground or root mealybugs are tiny, whitish insects that
feed on African violet roots, causing poor plant growth and wilting
of leaves between waterings. Avoiding overwatering will help to
control these insects.
Stunted plants with curled or distorted leaves may be an indication
of feeding by aphids. Both adults and nymphs are similar
in appearance, with soft, pear-shaped bodies, long legs and antennae.
Like mealybugs, aphids excrete honeydew, giving leaf surfaces a
shiny appearance and supporting the formation of sooty mold. Aphids
can be washed from infested African violets with a spray of lukewarm
water. See GreenShare Factsheet on aphids
for more information and control recommendations.
are small, slender insects characterized by long, hair-fringed wings.
They damage African violets by feeding on the leaves and flowers.
Typical leaf injury appears as irregular or streaked silvered areas
dotted with small, black drops of excrement. Flower feeding causes
distorted blooms, discoloration or streaking of petals and shorter
pesticides are necessary in order to control these insects, be certain
the product selected is recommended for use on African violets.
Donald H. Steinegger, John Watkins, Anne Vidave and Frederick P.
Nebraska Extension, 2000
are poisonous! Read and follow all safety precautions on labels.
Handle carefully and store in original containers out of reach
of children, pets or livestock. Dispose of empty containers
immediately, in a safe manner and place. Pesticides should never
be stored with foods or in areas where people eat.
When trade names are used for identification, no product endorsement
is implied, nor is discrimination intended against similar materials.
Be sure that the pesticide you intend to use is registered for
the state of use.
The user of this information assumes all risk for personal injury
or property damage.
information, call the URI CE Gardening and Food Safety Hotline
at 1-800-448-1011 or (401)874-2929 from outside Rhode Island;
Monday-Thursday between 9 am and 2 pm.
of Rhode Island Cooperative Extension provides equal program