Quick Guide: How to Grow Annual Geraniums in South Carolina
Zonal geraniums (Pelargonium x hortorum) are popular for their wide range of brilliant flower colors and attractive leaves.
Barbara H. Smith, ©2018 HGIC, Clemson Extension
Common Name: Geranium
Botanical Name: Pelargonium spp.
Plant Type: Annual flowering plant
Sun: At least 4 hours of direct sunlight daily
Soil: Well-drained soil
Water: Water regularly; allow the soil to dry between watering
Fertilizer: Fertilize every 4 to 6 weeks during the growing season
Planting Time: After all danger of frost is past and the soil has warmed
Uses: Bedding plants, containers, hanging baskets, window boxes
Height: Varies from 6 inches to several feet, depending on cultivar and care
Region: Grows in every part of South Carolina
How to Grow Annual Geraniums in South Carolina Landscapes
What Are Annual Geraniums?
Annual geraniums are popular for their wide range of brilliant flower colors and attractive leaves. They can be grown as bedding plants and in containers on decks and patios, in hanging baskets, or in window boxes. They will grow in every part of South Carolina.
Height and Spread of Annual Geraniums (Pelargonium)
There is great variation in the leaf, flower and growth habit of geraniums. They vary in height from 6 inches to several feet, depending on the cultivar and the care given to the plants.
Landscape Use of Annual Geraniums in South Carolina
Sun Exposure for Geraniums
- Geraniums need at least four hours of direct sunlight a day to flourish and flower well
- In very hot areas, it may be best to give the plants a few hours of shade midday.
When to Plant Geraniums Outdoors
Plant geraniums outdoors after all danger of frost is past and the soil has warmed.
Watering Geraniums in the Landscape
- Water abundantly after planting and continue watering regularly, allowing the soil to dry out between waterings.
- Never allow the plants to wilt, or the leaves will turn yellow and drop off.
- Keep water off the foliage because moist foliage favors the development of disease.
Mulching Geranium Beds
Mulch the bed to maintain moisture levels and keep the soil cooler in summer.
Best Soil and Fertilizer for Annual Geraniums in South Carolina
Soil Requirements for Geraniums
Soil for geraniums should be well-drained.
Fertilizer Needs for Geraniums
Geraniums respond well to fertilizer and are stunted and yellowed if not provided enough nitrogen.
- Fertilize new flowerbeds with one pound of a 10-20-10 (or equivalent) fertilizer per 100 square feet.
- Geraniums usually require additional fertilizer during the growing season every four to six weeks.
Mix the fertilizer into the soil well.
A water-soluble formula works well for follow-up fertilizations.
Pruning and Maintenance of Annual Geraniums
- Take dead flowers off the plant to prolong flowering.
- Pinch to encourage well-branched, full plants.
Growing Annual Geraniums in Containers in South Carolina
Container Size and Drainage
- When growing geraniums in containers, choose large pots to hold enough soil for a strong root system and to contain enough water to prevent wilting.
- Repot into larger containers if they grow so large that they wilt frequently.
- Select containers with adequate drainage holes, plant in a well-drained soil mix and do not allow pots to sit in water.
Common Geranium Problems and Pests in South Carolina
Edema on a florist geranium.
Penn State Department of Plant Pathology & Environmental Microbiology Archives, Penn State University, Bugwood.org
Disease and Physiological Problems of Geraniums
- Bacterial leaf spot/blight causes spotting of the leaves, leaf drop and black rot of the stems.
- Botrytis blight is common during cool, moist weather.
- Edema causes corky spots on the leaves and occurs when plants are over-watered.
Reduce watering frequency, keep water off leaves, increase air circulation, and make sure plants get enough sun to reduce these problems.
Keep plants cleaned of any dead, damaged, or yellowed leaves or flowers.
Insect Pests of Geraniums
Aphids, caterpillars, mites and whiteflies may infest geraniums.
Species, Types, and Cultivars of Geraniums (Pelargonium)
Common geraniums are actually members of the genus Pelargonium, while “true” geraniums include native wildflowers and herbaceous perennials.
Major types of geraniums grown by home gardeners include the following:
Common Garden Geraniums (Zonal Geraniums)
- These geraniums often have distinct leaf markings. There are fancy-leafed selections with tri-colored leaves, silver leaves and leaves with white markings.
- Flower colors are usually pink, red, salmon or white.
- Common and zonal geraniums are either seed-grown or cutting-grown.
- Geraniums from seed are available mainly in single-flowered form.Their flowers tend to shatter, an advantage because it isn’t necessary to pick off dead blooms.
A zonal geranium with white edged leaves.
Karen Russ, ©2008 HGIC, Clemson Extension
Flower colors for zonal geraniums (Pelargonium x hortorum) are usually pink, red, salmon, or white.
Barbara H. Smith, ©2018 HGIC, Clemson Extension
Seed-Grown Zonal Geranium Cultivars include:
- ‘Multibloom’: very early flowering; deeply-zoned leaves; small plants; up to 15 flower heads at one time, virtually hiding the foliage; pink, red, lavender, and white flowers
- ‘Cameo’: round heads of deep coral, salmon florets; lightly-zoned foliage
- ‘Maverick’: full flower heads in pink, red, salmon, and coral
- ‘Star’: vibrant pink and white bicolor; zoned foliage; multi-stemmed plants; up to 18 inches tall
Cutting-Grown Zonal Geranium Cultivars include:
Most geraniums root easily from stem cuttings, and many cultivars must be propagated this way to maintain flower and/or leaf color, shape, and scent.
- ‘Lollipop’: orange flowers
- ‘Gypsy’ and ‘Melody’: pink flowers
- ‘Melody Red’ and ‘Sincerely Yours’: red flowers
- ‘Lucille’: coral flowers
- ‘Lotus’: white flowers
- ‘Mrs. Henry Cox’: striking zonal geranium with pink flowers; dramatic yellow, deep red, and green variegated leaves
Ivyleaf geraniums (Pelargonium peltatum) have trailing growth habits with ivy-like leaves.
Barbara H. Smith, ©2018 HGIC, Clemson Extension
Ivy-Leaf Geraniums (Pelargonium peltatum)
These geraniums have a trailing habit with ivy-like leaves. They are used mainly in hanging baskets and window boxes.
Ivy geraniums differ from common zonal geraniums and prefer:
- Moderate temperatures
- Morning sun and afternoon shade above 85 °F
- Moderate soil moisture – not too much and not too little
One of the major problems seen on ivy geraniums is edema caused by fluctuating soil moisture.
Ivy-Leaf Geranium Cultivars include:
- ‘Summer Showers’: base-branching habit (pinching unnecessary); can grow from seed
- ‘Balcon’: later bloomer; smaller flowers than common ivy geraniums, heavier bloomer; trails two feet from a container (even on the north side of a house); “self-cleaning” flowers, no deadheading required
Scented-Leaf Geraniums
The “mosquito geranium” (Pelargonium citrosum) smells like citronella and is advertised as a natural mosquito repellent. This has not been proven.
Barbara H. Smith, ©2018 HGIC, Clemson Extension
These geraniums are prized for their aromatic leaves, as most do not have showy flowers.
Scents include:
- Lemon
- Rose
- Peppermint
- Nutmeg
Leaves may be used for:
- Potpourris
- Preserves
- Desserts
- Punches
- Vinegars
- Teas
- Sachets
Common Scented Geranium Species include:
- Rose geranium (Pelargonium graveolens): hairy, deep green, divided and toothed leaves; delicate, spicy rose scent
- Lemon geranium (P. crispum): grows to 2 feet high; small, stiff, curly leaves; lilac-pink flowers; fresh leaves give a pleasant lemon fragrance
- Apple geranium (P. odoratissima): trailing stems; small, soft, gray-green leaves; sweet apple scent; delicate white flowers
- Peppermint geranium (P. tomentosum): large, heart-shaped, woolly leaves; strong mint scent
- The “mosquito geranium” smells like citronella and is advertised as a natural mosquito repellent. This has not been proven.
(Pelargonium x domesticum ‘Regal’) are not heat tolerant and are best grown as house plants during cooler months.
Barbara H. Smith, ©2018 HGIC, Clemson Extension
Martha Washington and Regal Geraniums
Heat Sensitivity of Regal Geraniums
These are sold during the winter as flowering pot plants. They are not heat-tolerant and will not perform as well outdoors as common geraniums.
How to Overwinter Geraniums in South Carolina
Geraniums can be overwintered by three methods:
Overwintering Geraniums by Taking Cuttings
- Take cuttings in the fall
- Keep the plants on a bright, sunny windowsill during the winter
Overwintering Geraniums as Potted Plants
- Dig large geraniums before the first frost
- Plant them in large pots
- Cut back
- Place in a sunny area such as a heated porch
Overwintering Geraniums as Dormant Plants
- Dig plants before the first frost
- Hang them upside down in a cool, moist basement where they will not freeze
- In spring, take the plants down
- Cut off two-thirds of the top growth
- Replant outdoors
Originally published 03/99
