Geraniums are one of the most common garden flowers in Kentucky and across the nation. They have a wide appeal and range of climatic adaptability. Geraniums are popular for their continuous flowering throughout summer and into fall. Plants perform equally well in containers on the patio, hanging baskets and in ground beds.
Geraniums have been significantly improved in the last 15 years. Breeding programs for geraniums have developed the following improvements: (1) compact plants that branch freely, (2) long lasting, non-shattering flowers, (3) disease and insect resistance, (4) increased flowering, (5) a greater selection of different growth habits and colors.
Traditional bedding geraniums or zonal geraniums are propagated from seeds or cuttings. Cutting geraniums are maintained by large commercial propagators and kept disease-free. In the fall rooted cuttings are sold to local growers who grow these cuttings into their own stock plants, to produce typical geraniums for spring. Thus, before geraniums reach the consumer, they have used a lot of greenhouse space, time, heat, and labor. It's not surprising that they cost more than other spring bedding plants.
Geraniums produced from seed require a great deal of time in the greenhouse as well. Seeds are sown in December or early January and grown under a precise schedule of supplemental lighting and growth regulator treatment to produce plants for spring sales.
Ivy and scented geraniums are also available for Kentucky home gardeners. Ivy geraniums are generally grown as beautiful hanging baskets for spring sales. Scented geraniums, with various fragrances from aromatic oils in leaves, are used by herb fanciers in their gardens.

Garden Performance
Traditional bedding or zonal geraniums and scented geraniums grow best in full sun garden locations. They may tolerate partial shade or shade for 4 to 6 hours each day, but grow taller and produce fewer flowers. Geraniums grow to be 18 to 24 in. tall and 12 to 18 in. wide. Plants should be spaced 15 to 18 in. apart in beds or containers.
Ivy geraniums should be grown in full shade. These plants prefer a cooler climate than most Kentucky summers, so keep them in a shady cool location. Although they are generally grown in hanging baskets, ivy geraniums can be grown successfully in shady ground beds.
Be sure to choose a garden site that is well-drained. If you must use a low area for your garden, build a raised bed to be sure drainage will be adequate. Ivy geraniums prefer organic soils when grown in shade. Add extra organic matter to gardens in shady locations since these areas tend to dry more slowly than sunny locations.
Patio containers, window boxes and pots should always allow water to drain freely. Use growing media in your containers; garden soil is NOT recommended. The best growing media for these plants are professionally prepared, packaged media (e.g., Pro-Mix®, Metro-Mix®, Ball Growing Mix®) used by greenhouses for plant production. A satisfactory home-made growing medium would be composed of 1 part sterile garden soil, 1 or 2 parts of sphagnum moss peat, black (Michigan) peat or compost, and 1 part perlite or coarse sand.
Typical garden soils are adequate for growing geraniums. Garden soils with organic matter added annually will provide good water drainage and aeration and retain adequate moisture and nutrients. Addition of organic matter from any source (e.g. straw, rotted leaves or manure, grass clippings, peat moss, etc.) is best to assure a beautiful display from your plants.

Plant Care
Geraniums will show maximum growth if you follow these steps for water and fertilizer:
1.Plants require about 1 in. of water per week. If rainfall does not supply enough water, apply necessary water in one application, preferably before 7 pm. Organic or plastic mulches will reduce water requirements.
2.Plants growing in containers will need water every 2 to 4 days throughout summer. Hanging baskets generally dry out faster than other containers.
3.New transplants should be watered with a complete water-soluble fertilizer (e.g., 20-20-20) shortly after transplanting.
4.Granular, dry fertilizer can be added to garden soil when it is tilled in spring. Use approximately 1 lb of 15-15-15 (nitrogen-potassium-phosphorus) fertilizer per 100 sq ft of garden or 1-1/2 lb of 10-10-10 or 3 lb of 5-10-5 fertilizer per 100 sq ft.
5.Dry fertilizer or water soluble fertilizer applied in early August will stimulate late summer growth. Apply dry fertilizer between the plants, scratch it into the soil and water the garden thoroughly. Use dry fertilizer at one half of the rates described above. Water soluble fertilizers should be used regularly for container plants according to label recommendations. Geraniums are heavy feeders and require fertilization throughout summer for satisfactory growth.
Geraniums are relatively free of insect problems; however, ivy geraniums are susceptible to damage from spider mites. Occasionally cutworms or caterpillars will feed on geraniums. They can be readily detected by the cut edges of leaves where they feed. If only a few are responsible for the damage, the best control is hunting down the culprits and destroying them individually rather than spraying the entire bed.

Diseases
Black Rot Disease
Black rot or blackleg is caused by Pythium organisms. The disease appears as a black rot on stems. The best control is to pull out diseased plants and destroy them, or fungicides can be used against this disease.

Bacterial Disease
Bacterial stem rot and leaf wilt is caused by bacteria transmitted from infected soil by splashing water. The disease causes basal rot or dieback on growing points of older plants. Control by destroying infected plants.

Gray Mold
Botrytis blight or gray mold is caused by the common mold Botrytis cinerea. Spores are air-borne and germinate when they come in contact with wet foliage. To control blight avoid watering the foliage, especially in the evening and whenever humidity is high. Also, since gray mold starts most frequently on old decayed leaves and flowers, regularly remove and destroy old leaves and flowers.

Viruses
Several strains, such as crinkle virus or leaf curl virus, are known to affect geraniums. Young leaves are wrinkled and deformed, with colorless spots that are slightly thickened. Prevent this disease in your garden by using virus-free plants. Discard diseased plants as soon as you notice them.

Recommended Geraniums for Kentucky Gardens¹
I. Zonal Geranium (Pelargonium X hortorum)
A. Zonal Geraniums from cuttings
These geraniums are characterized by
1. larger flowers that are more tolerant to flower shattering from rain, wind and handling
2. vigorous plants with larger flowers for spring sales, but mediocre garden performance from July to September
3. susceptibility to bacterial wilt; plants may be sold with this uncontrollable disease problem.
 

Cultivars		Description
Brocade ® Series: Dolly Varden, Wilhelm Langguth, Happy Thoughts		Geraniums with variegated foliage and red or pink flowers. Outstanding performance throughout summer.
Goldsmith Americana® Series: Red, Rose, Pink, White, etc.		Traditional geranium cultivars. Variable summer performance, generally good in containers.
Oglevee® Series: Aurora (lavender), Kim (scarlet), Snow White (white), Veronica (magenta), etc.
Fischer Pelfi® Series: Blues (hot pink), Bravo (pink), Mars (purple), Tango (red), etc.
Yours Truly (red), Sincerity (red)

B. Zonal Geraniums (bedding geraniums) from seed
These geraniums are characterized by
1. smaller flowers susceptible to shattering from rin, wind and handling
2. vigorous plants with small flowers for spring sales, but outstanding garden performance throughout summer until frost; plants branch freely and produce many flowers
3. freedom from disease.
 
 

Cultivars		Description
Elite Series: Red, Cherry, Coral, Salmon, etc.		Geraniums with red, rose, salmon, pink, white and bicolor flowers plus a few with double flowers. All cultivars have outstanding garden performance
Ringo 2000 Series: Scarlet, Salmon, Rose, etc.
Multibloom Series: Red, Salmon, etc.
Pinto Series: Coral, Bright Pink, Rose, Snow, etc.
Dynamo Series, Avanti Series
II. Ivy Geranium (Pelargonium peltatum)
Cultivars		Description
Balcon Series: Red, Pink, Salmon Sybil Holmes (pink), Yale (red), Double Lilac White, Cornell (lavender), Salmon Queen pink), Peppermint Candy (red and white) Fischer: Barock (red), Butterfly (lavender), etc.		Plants have a spreading or hanging form when grown in ground beds or containers (hanging baskets or window boxes). Commonly sold in hanging baskets in the spring.
Cascade: Bright (red), Lila (purple), Sofie (pink), etc.

III. Scented Geraniums
Species and cultivars are selected for the odor or fragrance of the foliage and foliage form. Some are used as culinary herbs.
 

Rose-Scented Geranium	Sweet Scented Geranium
Orange Geranium	Coconut Geranium
Lemon Geranium	Lime Geranium
Nutmeg Geranium	Apple Geranium
Knotted Geranium	and many others
Pheasant's Foot Geranium

¹ Recommendations based on trial and observations in the College of Agriculture's Landscape Garden Center from 1980-1985.