J. Raymond Kessler, Jr., Bridget K. Behe, and James S. Banno

Gardening consumers are often bewildered by the wide range of flower colors and types of summer annuals available in the retail market. Consumers typically purchase warm-season bedding plants from late March to May for planting in commercial or home landscapes.

Bedding plant cultivars are frequently developed and marketed in a series. Cultivars in a series share common characteristics such as height, growth habit, or disease resistance, but differ from each other in flower color. The name on the label often begins with the name of the series followed by the flower color, e.g. ‘Carpet Blue’. The majority of bedding plants are purchased in plastic market packs from garden centers, grocery stores, mass market outlets, and home centers. These retail outlets maintain large displays containing a wide selection of bedding plants in a variety of types, sizes, and flower colors. However, this selection often contains species and cultivars which are popular and perform well in middle and northern parts of the eastern United States, but may not perform well in Alabama.

Unique to Alabama and surrounding states are extended periods of hot, humid weather, periodic violent thunder storms, and periods of drought. These climatic stresses challenge many traditional bedding plants to remain healthy and floriferous throughout the long growing season. Many petunia cultivars for example become unattractive in mid to late summer because of elongated, “spindly” growth and damage to delicate flower petals from strong wind or rain. Older cultivars of zinnia contract foliar diseases such as powdery mildew during humid weather causing lower leaf loss. Most bedding plants must receive some supplemental water during periods of extended drought. Information on garden performance of different bedding plants for the hot, humid environment of Alabama is needed. Therefore, during the summer of 1997 we evaluated more than 300 cultivars for their garden performance.

METHODS
The trial consisted of 323 cultivars from 23 different bedding plant species at the E.V. Smith Research Center in Shorter, Alabama. The research center is located 26 miles east of Montgomery, Alabama. Seeds for the trial entries were donated by companies and plants were grown by Wright’s Greenhouse and Nursery, Inc., a nearby commercial transplant producer. Every effort was made to grow the plants using cultural practices that the typical homeowner might use. Raised flower beds were tilled and amended with agricultural limestone and controlled-release fertilizer (18-6-12) according to soil test recommendations. After transplanting, the flower beds were mulched with pine bark nuggets. No additional fertilizer was applied during the season. No fungicides or insecticides were applied during the trial period.

All bedding plants were grown in full sun, with the exception of impatiens, which were grown under 60% black shade fabric. Rainfall was supplemented using overhead sprinkler irrigation to provide an equivalent of 1 inch of water per week. No deadheading of spent flowers or other maintenance was performed on any of the plants with the exception of hand weeding.

Plants from each entry were evaluated every 2 weeks from July 3 through September 29, 1997 using a 1 to 5 scale. Flowering plants were rated primarily on their floral displays, while size, shape, and freedom from insect or disease blemishes were also considered. A rating of 1 indicated a small display of foliage with no flowers present; 2–adequate amount of foliage with one or two flowers present; 3–sufficient foliage and floral display to be attractive in the landscape; 4–above average floral display and sufficient foliage display; and 5–superior floral display and sufficient foliage display. A rating of 0 indicated the plant had died. Any plant rated an average of 2.5 or higher could be considered acceptable in the landscape and would be a worthwhile addition to a garden located in temperate zone eight.

RESULTS
Highest overall rating were received by impatiens and wax begonia (Begonia × semperflorens) with 23 impatiens and 20 wax begonia cultivars receiving ratings greater than 3.0 (see table). Many impatiens cultivars in the ‘Super Elfin’ and ‘Dazzler’ series performed well. Wax begonias in the ‘Eureka’ series also performed well and are upright, tall growing types of begonia as opposed to the short rounded form of the more popular types. Three cultivars of ageratum (Ageratum houstonianum) had ratings greater than 3.0.

Annual vinca is noted for its tolerance of hot, dry locations in the landscape. All the annual vinca (Catharanthus roseus) cultivars in the trial received ratings higher than 2.5, nine had ratings greater than 3.0, and ‘Pacifica Orchid’, ‘Pacifica Punch’, and ‘Blue Pearl’ received the three highest ratings.

Three species of cockscomb were evaluated in 1997. Three plume cockscombs (Celosia plumosa)—‘Castle Yellow’, ‘Century Red’, and ‘Forest Fire’—and two spike cockscomb (Celosia spicata)—‘Flamingo Purple’ and ‘Flamingo Feather’—were rated higher than 2.9. However, cultivars of crested cockscomb (Celosia cristata) did not perform well with ratings less than 2.0.

Globe amaranth (Gomphrena globosa) is an old-fashion annual that is regaining popularity in the southeast due to its excellent heat tolerance and the development of new cultivars. Three cultivars evaluated in 1997 received ratings higher than 2.8—‘Woodcreek Red’, ‘Woodcreek Lavender’, and ‘Woodcreek Rose’. Another old-fashion annual, flowering tobacco (Nicotiania alata), had two cultivars receiving acceptable ratings (higher than 2.5)—‘Prelude Rose’ and ‘Prelude Red’.

Zinnias (Zinnia elegans) have been grown in the southeast for more than a century, but are prone to foliar fungal diseases. Two cultivars that rated higher than 3.0 and appeared to be disease resistant were ‘Oklahoma Formula Mix’ and ‘Blue Point Formula Mix’. Though a recent introduction to southern gardens, creeping zinnia (Zinnia angustifolia) is quickly proving its toughness and reliability. Unlike its upright counterpart, creeping zinnia is a low, spreading plant with characteristics similar to a flowering ground cover. Two cultivars rated higher than 2.5 in the 1997 trial—‘Goldsmith’ and ‘Star White’.

Of the 76 cultivars of petunia in the 1997 trial, only nine rated 3.0 or higher. Most of these can be found in a variety of flower colors in the ‘Carpet’ series. A new development in petunias for warm climates is the tropical or spreading petunia. ‘Purple Wave’ and ‘Pink Wave’ appeared to thrive in the summer heat, rating 3.3 and 3.0, respectively. Portulaca (Portulaca grandiflora), which also has a spreading growth habit, had two cultivars rated 2.5 or higher—‘Sundial Fuchsia’ and ‘Sundial Orange’.

Gardeners often rely on marigolds as a mainstay of the annual planting. There are two types of marigolds. African marigolds (Tagetes erecta) are generally tall with large flowers while French marigolds (Tagetes patula) are more compact with more numerous, but smaller flowers. Eight African marigolds and 17 French marigolds rated 2.5 or higher but only two rated greater than 3.0. The top two, ‘Bonanza Harmony’ and ‘Bonanza Flame,’ are of the French type.

Most gardeners think of red-flowered scarlet sage (Salvia splendens) when annual salvia is mentioned. However, none of the 17 cultivars evaluated in 1997 received ratings higher than 3.0. A better salvia for the southeast is mealy-cup sage (Salvia farinacea). One cultivar rated 3.0 or higher, ‘Victoria White’.

Verbena speciosa ‘Imagination’ was another excellent performer that received a rating of 2.5. This plant can be treated as a perennial in south Alabama. It has a low growing habit with finely dissected leaves and dark purple blooms which lasted into the fall.
Seed companies and retailers are constantly developing new bedding plant cultivars and products. Recently, they have focused their efforts on the growing southern market by developing new bedding plant types and cultivars for warm environments. Ongoing research is needed to evaluate these new products for their performance in the southern landscape.