Geraniums for Florida - Manatee County Extension Office ...

CIR472
Geraniums for Florida 1
R. Schoellhorn 2
longer lasting, nonshattering flowers, earlier bloom,
disease and insect resistance and a larger selection of
different growth habits, foliage and flower color.
Figure 1. Pink geraniums planted in a mixed container with
white angelonia, pink sutera, and coleus. Geraniums are
used as winter flowers in south and south central Florida,
and as spring annuals in the northern parts of the state.
General Information
More than half the flower growers and retail
nurseries in the United States grow or sell geraniums,
indicating their wide appeal and adaptability to a
range of climates. Geraniums are popular for their
continuous flowering throughout the summer and
early fall in most of continental United States and
Canada.
Commercial producers and public institutions are
actively breeding better geranium cultivars that have
compact growth, increased branching and flowering,
Geraniums are planted as soon as danger of frost
is past in the spring in northern United States and
Canada. Plants usually grow best at night
temperatures of 60 to 65°F (16 to 18°C) and day
temperatures of 70 to 85°F (21 to 29°C). In Florida
the high summer temperatures retard their growth and
flowering. Therefore in south Florida and the Keys
geraniums should be planted in October or
November. In central and north Florida where hard
freezes occur during the winter, geraniums should be
planted after the last frost in March.
For Floridians, geraniums pose some problems.
They cannot tolerate a freeze, but they also do poorly
in our summer heat and humidity. So, when is it best
to grow them? For south Florida they become a
winter flower, for central Florida they are best used in
early spring, and for north Florida their season of
interest is usually so short that they are not used
heavily.
1. This document is Circular 472, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. First published:
June 1990. Reviewed: March 1991. Reviewed and revised October 2003.
2. Rick Shoellhorn, associate professor, commercial floriculure specialist, Environmental Horticulture Department, Institute of Food and Agricultural
Sciences, University of Florida, Gainesville FL 32611.
The use of trade names in this publication is solely for the purpose of providing specific information. It is not a guarantee or warranty of the products named,
and does not signify that they are approved to the exclusion of others of suitable composition.
The use of trade names in this publication is solely for the purpose of providing specific information. UF/IFAS does not guarantee or warranty the
products named, and references to them in this publication does not signify our approval to the exclusion of other products of suitable composition.
The Institute of Food and Agricultural Sciences (IFAS) is an Equal Employment Opportunity - Affirmative Action Employer authorized to provide
research, educational information and other services only to individuals and institutions that function without regard to race, creed, color, religion,
age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For information on obtaining other extension
publications, contact your county Cooperative Extension Service office. Florida Cooperative Extension Service / Institute of Food and Agricultural
Sciences / University of Florida / Larry R. Arrington, Interim Dean

Geraniums for Florida 2
Some tips on getting the most from geraniums:
1. Avoid using geraniums where there is
overhead watering or where they can get wet in our
afternoon rains. A covered patio, or under the eave of
a house is perfect; just make sure they get lots of
sun.
2. Plant as early as possible; geraniums can take
a light frost if they have had a chance to adjust to cool
temperatures. Late plantings generally are short
lived.
3. Keep geraniums in pots where they get better
air circulation and you can keep them slightly drier
than in the garden.
4. Always mulch any plantings of geraniums in
the ground. Most of their disease problems originate
in the soil, and when rain splashes dirt onto the leaves
geraniums begin to decline quickly.
5. Look for plants better suited to Florida's
climates, plants that require less care and chemicals to
keep them looking their best. Try using pentas,
coleus, and other heat-loving annuals that have a
longer season and are more trouble free.
Culture
Geraniums grow best in full sun. They will
tolerate partial shade, but usually will grow tall,
producing few lateral branches and flowers. They
should be spaced 18 inches apart in flower beds. To
avoid disease problems and to give a well-groomed
appearance, old flower heads should be removed.
Soil. Geraniums grow best in soils that provide
good drainage and aeration and have good moistureand
nutrient-retention capacities. Florida's sandy
soils should be amended with organic matter.
Incorporation of 2 to 3 inches of organic matter into
planting beds will increase the water- and
nutrient-holding capacities of the soil. Organic
materials such as leaf mold or peat moss should be
thoroughly mixed into the soil.
In areas where the soil is very poor, it is easier
and less expensive to transplant small plants into
inexpensive plastic 2- to 4-gallon (7.6 to 15.1 liters)
pots filled with good organic soil and place the pots
into flower beds in the yard. Sink the pots into the soil
until the top surface of the pots is at soil level. Mulch
with grass clippings, cypress bark or any other
mulching material.
Fertilization. Garden soils, especially in new
flower beds, are frequently infertile. Flower beds
should be fertilized before planting or at planting time
with complete soluble or partially soluble fertilizers.
Use a complete fertilizer such as 6-6-6 or similar
analysis fertilizer at the rate of 2 pounds (908 grams)
per 100 square feet (9.3m 2 ). The fertilizer can be
incorporated when preparing the beds or it can be
broadcast on top of the soil. Fertilizers should be
applied early in the growing season and repeated
monthly.
In recent years, controlled-release fertilizers have
become available. These fertilizers release their
nutrients slowly, thereby reducing frequency of
application. Controlled release fertilizers can be
incorporated uniformly throughout the soil on new
geranium plantings. Surface applications are most
effective on established plantings. (See Table 1.)
Mulching. Mulching is a good practice to
prevent weed growth and conserve soil moisture. In
addition, mulching prevents injury from rain and
overhead irrigation. Splashing water combined with
loose particles of sand rasps leaves and causes injury.
Grass clippings, straw, wood chips, sawdust and
compost can be used as mulches.
Water. Water geraniums during dry periods to
prevent wilting, eventual yellowing and dropping of
leaves. The moisture content of the soil can be
determined by picking up a handful of soil and
pressing it in your palm. If it crumbles, the plants
should be watered. Soil should be kept moist but not
too wet. Keeping the soil wet encourages snail and
slug populations that chew the foliage, and wet soil
invites root-rotting organisms. Avoid overhead
irrigation where possible, since wet flowers
deteriorate very rapidly.
Growing Geraniums in Containers
Geraniums will grow well in pots and planters.
Pots and planters should have drain holes to allow
outflow of excess water. Pot and planter geraniums

Geraniums for Florida 3
grow best in well-aerated soil mixes such as 1/3
native soil, 1/3 peat and 1/3 sand by volume.
Incorporate 1/3 cup (3 ounces or 85 grams) of
superphosphate, 1/3 cup (4 ounces or 113 grams) of
dolomite and 1/5 cup (2 ounces or 85 grams) of a
minor element mix into each cubic foot of soil mix.
An easier way is to purchase sterilized ready-made
soil mixes from garden stores.
Overwintering
Geraniums will grow as a perennial in areas
where frost is seldom experienced, such as Key West
and Dade County, and protected areas in central
Florida. This practice is discouraged since plants will
grow out of bounds and become unsightly. Plants
overwintered in the garage or indoors will not do
well. Best results will be realized when new, good
quality plants are used at each planting.
Selection
Finding the best geraniums for Florida is
difficult as the cultivars for sale in nurseries change
year to year. The following tables are meant only to
give you an idea of where to look, but the types of
geraniums listed in the tables may or may not be
available at your local nursery. In general, your best
bet is to follow the culture guidelines in this article
and the tips listed on the front page. Properly grown,
almost all geraniums do well in their season.
Traditionally, geraniums were propagated
exclusively by vegetative means with commercial
operators rooting cuttings from disease-free stock
plants and selling them to local growers. Local
growers used these rooted cuttings as stock plants
from which they vegetatively propagated plants for
sale. Important vegetatively propagated geranium
cultivars as measured by their sales nationwide are
presented in Table 2 .
Recently, there has been a trend toward growing
geraniums from seeds. Seed-propagated geraniums
perform as well as vegetatively propagated material
and produce smaller plants at less cost to the
consumer. Seed-propagated geraniums branch freely,
are more compact and grow faster than vegetatively
propagated plants. Seed geranium cultivars that are
available and have shown outstanding performance in
home gardens across the nation are presented in
Table 3 .
There are also a group of geraniums called the
ivy geraniums that are used in hanging baskets and
mixed containers. This type of geranium is even
more sensitive to heat and humidity, so for best
results with ivy-type geraniums, keep them out of the
rain and provide some protection from midday sun
and heat. See Table 4.
Pests
Occasionally cutworms and caterpillars will feed
on geraniums. These insects can be readily detected
by the chewed edges of leaves where they feed. If
only a few are responsible for damage, they should be
destroyed individually rather than by spraying the
entire bed. Through periodic close examinations,
insects can be detected and control measures taken
before the entire flower bed is infested.
For information on pesticides effective against
various insects, contact your local county extension
office. Follow label recommendations when spraying
and thoroughly cover underside of leaves where
many insects feed.
Diseases
Pythium blackleg. Black rot or pythium
blackleg, caused by the fungus pythium, has been
observed for many years to attack geraniums. Losses
from pythium infestation occur mainly in
propagation, but the disease also can be found on
young plants.
Pythium blackleg shows up first as a brown
water soaking of the stem bases or at wounds on
young plants. The rotted areas enlarge rapidly and
turn coal black, progressing 3 or 4 inches up the stem
from the base of the plant. Leaves wilt when the rot
girdles the stem and death of the entire plant soon
follows.
Blackleg may sometimes be confused with
bacterial stem rot and in some cases both diseases
may be found in the same group of plants. Plants
affected with blackleg disease have a shiny, coal
black, slimy, wet appearance and the rot progresses

Geraniums for Florida 4
rapidly, often killing plants within a week or so.
Plants affected with the bacterial stem rot have a
dull-brown appearance and plants may not die for
several weeks.
Pythium blackleg is spread primarily by infested
soil in the flower bed area or potting media. The
fungus also may enter plants' roots by way of holes in
the bottoms of pots if they are placed on infested
gravel, cinders or soil. There is some chance of
spread through the use of propagation material from
diseased plants. The best control is to pull out
diseased plants and destroy them. A commercial
fungicide specific for pythium can be used if the
disease is in the initial stages.
Bacterial stem rot. Bacterial stem rot is caused
by bacteria, which can be transmitted from infected
soil by splashing water. The disease causes basal rot
or die back on the growing points of older plants.
This disease can be controlled by destroying infected
plants.
Botrytis blight. Botrytis blight is probably the
most common disease of geraniums. It is caused by
Botrytis cinerea, a fungus that primarily lives on
aging and dead tissue such as flowers, leaves, broken
stems and cutting stubs. Under the right conditions it
can attack and cause severe damage to leaves, stems
and flowers of healthy plants, especially if they are
soft and succulent.
where parts of plants have been removed, or to
healthy tissue if sufficient moisture is present.
Botrytis is a fungus that primarily lives on dead
and aging plant tissues such as flowers, leaves and
broken stems; thus, the probability of its spores being
present in large numbers is in direct proportion to
sanitation practices of the gardener. The more dead
leaves and old flowers on the plants, the larger the
number of potential disease-causing spores and the
greater the chance of occurrence of the disease.
To control botrytis blight, avoid watering the
foliage, especially in the evening and whenever
humidity is high. Also, remove and destroy old,
decayed leaves and flowers. Spraying with an
appropriate fungicide should control the fungus.
Viruses. Several virus strains are known to affect
geraniums. Crinkle or leaf curl virus causes wrinkled,
deformed, young leaves, with colorless spots that are
slightly thickened. The spots expand and turn yellow
and finally develop into necrotic areas. This disease
can be prevented by using virus-free plants. Diseased
plants should be rogued out as soon as they are
noticed. Yellow net vein virus causes yellow
coloration of leaf veins. Control is the same as for
other virus diseases: sanitation and control of insect
vectors.
The disease shows up on the blossoms as
premature fading and drying of petals. The central
florets are often the first to be affected. During
periods of high moisture, affected blossoms may be
covered with grayish brown masses of spores and the
florets may be matted together.
The leaf spot phase of botrytis blight often
appears when petals from affected blooms fall on the
leaves and the pathogen attacks healthy leaf tissue.
The leaf spot usually assumes the outline of the
infected flower part that falls upon the leaf. However,
when leaves are wet or the humidity is high, spots
enlarge and become irregular, brown and
water-soaked. If the high humidity continues, the
spots become covered with grayish brown masses of
spores. These spores are light and are carried by air
currents or by splashing water to flowers, to stubs

Geraniums for Florida 5
Table 1. Suggested application rates of controlled release fertilizers for geraniums grown in flower beds or containers.*
New Plantings
100 sq/ft (9.3 m 2 ) of bed incorporated 4" (10
cm) deep
Established Plantings
Osmocote®
14-14-14
lasts 2-3 months
4 to 5 lbs
(1.8 to 2.3 kg)
100 sq/ft (9.3 m 2 ) of bed surface applied 5 to 7 lbs
(2.3 to 3.2 kg)
1 gallon (3.8 liters) container 1 heaping tsp.
(approx. 6 cm 3 )
2 gallon (7.5 liters) container 2 heaping tsp.
(approx. 12 cm 3 )
3 gallon (11.4 liters) container 3 level tsps.
(15 cm 3 )
Sierrablen® Nursery
mix + iron19-6-10
lasts 4-5 months
3 to 4 lbs
(1.4 to 1.8 kg)
4 to 5 lbs
(1.8 to 2.3 kg)
1 level tsp.
(5 cm 3 )
2 level tsps.
(10 cm 3 )
3 heaping tsp.
(approx. 18 cm 3 )
Osmocote®
18-6-12
lasts 4-5 months
2 to 3 lbs
(0.8 to 1.4 kg)
7 to 8 lbs
(3.2 to 3.7 kg)
1 level tsp.
(5 cm 3 )
2 level tsps.
(10 cm 3 )
3 heaping tsp.
(approx. 18 cm 3 )
*The above rates are maximums. Do not exceed these recommendations. The above rates should be reduced when a
build up of salinity occurs (for instance, as a result of infrequent or light irrigation, poor drainage, or high salinity levels in
irrigation water), when potted plants are growing in shaded or low-light locations and/or when plants have been
previously supplied with water-soluble fertilizers.
Table 2. Vegetatively propagated geranium cultivars.
Cultivars
Red
Red Perfection
Improved Richard
Irene
Sincerity*
Cardinal
Dark Red Irene
Yours Truly
Pink
Skylark
Genie Irene
Penny Irene
Quest
Salmon Supreme
Description
Intense orange red. Similar in performance to 'Sincerity,' with large, brilliant, prolific flowers.
Orange red. Fine outdoor durability and somewhat non-shattering flowers. Shorter growth
habit, slower and less prolific than 'Irene.'
Rose red. Early and prolific flowering. Flowers shatter badly and are susceptible to botrytis.
Brighter, more intense color than 'Irene' and 'Improved Richard.' Larger and more showy
flowers than 'Irene.' Does not shatter as much and is botrytis resistant and self branching with
stocky growth.
Scarlet red. Intermediate color between 'Irene' and 'Dark Red Irene.' Strong growth habit and
more vigorous than 'Dark Red Irene.' Strong flower stems.
Dark red. Similar to 'Irene' but a deeper color.
A sport from 'Sincerity' that blooms earlier and has more flowers and shorter growth habit.
Other characteristics are identical to 'Sincerity.'
Large medium pink, profuse flowering and semidouble. Plant is erect, vigorous, bushy and
compact.
Rose pink. Self branching and compact. Prolific bloomer, sensitive to shattering and
susceptible to botrytis.
Dark salmon. Earlier flowering than the other Irenes. Large flowers with moderate shattering.
Susceptible to botrytis in prolonged wet conditions.
Bright rose pink, large flowers. Other growth habit similar to 'Sincerity,' somewhat shorter.
Attractive salmon pink similar to 'Didden's Improved Picardy.' Little shattering, but susceptible
to botrytis under wet and humid conditions.

Geraniums for Florida 6
Table 2. Vegetatively propagated geranium cultivars.
Cultivars
Springtime Irene
Didden's
Improved Picardy
Salmon Irene*
Enchantress Fiat
White
Snowmass
Snowman*
Modesty
Summer Cloud
Description
Salmon pink. Similar in color to 'Salmon Supreme' and 'Didden's Improved Picardy.' Most
compact grower in the 'Irene' family. Its early and free flowering characteristics make it very
attractive. Less shattering, but most sensitive to botrytis of the 'Irene' series.
Salmon pink. Early prolific bloomer with excellent flower form. Compact growth habit. Large
flowers, nearly shatter proof. Fine spring performance but susceptible to botrytis and develops
foliar problems under high temperature conditions.
Dark salmon, bright color, most prolific blooming variety in the 'Irene' family. Compact,
self-branching habit. Flowers shatter and do not tolerate summer heat. Susceptible to botrytis
in wet outdoor conditions.
Light salmon pink. The leading light pink. Rated highly for its compact growth habit, attractive
color, prolific flowering, and speed. Major objection is extreme sensitivity to bacterial wilt.
Produces more flowers in the garden than any other white geranium. Upright growth habit, but
not leggy. Flowers are shatter resistant and less sensitive to botrytis.
White flowers.
A white Irene similar in growth characteristics to 'Irene.'
Large semidouble flowers, partially shatter proof and flower form resembles 'Irene.' More
spreading than 'Snowmass.'
Purple
Springfield Violet* Rose purple flowers.
*Cultivars that perform well under Florida's growing conditions.
Table 3. Seed geranium cultivars.
Cultivars
Nittany Lion (Inbred cultivar)
Red Express*
Ringo Rose*
Showdon*
Carefree Series
Carefree Bright Rose
Carefree Bright Pink
Carefree Crimson*
Carefree Deep Salmon
Carefree Fickle Rose
Carefree Fickle Scarlet
Carefree Light Pink
Carefree Light Salmon
Carefree Picotee
Carefree Red
Carefree Scarlet
Carefree White
Carefree Coral
Sprinter series
Description
Bright red, single florets borne in large compact trusses. Variegated leaves.
Red.
Rose.
White.
Bright rose, compact habit and early bloom. Deep green foliage.
Bright pink, compact habit and early bloom. Deep green foliage.
Intense crimson, deeper in color than 'Carefree Scarlet.' Well-defined zonal
markings on leaves.
Early bloom. Leaves lightly zoned.
Rich rose florets with white centers.
White throat.
Soft delicate pink.
Soft, luminous salmon.
White with pink edge.
A deep salmon red.
Scarlet blooms, compact habit and early bloom. Deep green foliage.
White flowers, compact habit and early bloom. Green foliage.
Glowing coral salmon with leaves deeply zoned.

Geraniums for Florida 7
Table 3. Seed geranium cultivars.
Cultivars
Description
Sprinter Scarlet
Salmon scarlet. Dwarf habit.
Sprinter Deep Red
Vermillion red.
Sprinter Salmon
Medium salmon.
Sprinter White
Pure white under most growing conditions.
Flash series
Fire Flash*
Vermillion red.
Salmon Flash
Deep salmon.
Scarlet Flash
Scarlet.
Sooner series
Sooner Red
Bright vermillion scarlet.
Sooner Deep Salmon
Bright coral-salmon flowers, long bloom season. Green foliage.
*Cultivars that perform well under Florida's growing conditions.
Table 4. Ivy geraniums for Florida.
Stardom Series
Global Red Peppermint
Global Neon Cherry
Cascade and Blizzard
Series
Many colors available, heat tolerant and vigorous.
Burgundy and white flowers, heat tolerant. FloraStar winner
Hot pink ivy geranium has semi-double florets with a medium
green foliage, heat tolerant. FloraStar winner.
Many colors in the series. Also known for strong performance and
heat tolerance.
Table 5. Websites of the major breeders of geraniums in the United States and Europe.
Fischer Geraniums
Oglevee Geraniums
Proven Winners
Ball Corporation
FIDES North America
The Flower Fields
http://www.fischerusa.com
http://www.oglevee.com
http://www.provenwinners.com
http://www.ballfloraplant.com
http://www.fidesnorthamerica.com
http://www.ecke.com