Summer annuals, which are plants that complete their life cycle in one growing season, have attractive displays of color that help create an attractive landscape. Though the plants have higher maintenance requirements than herbaceous perennials, trees and shrubs, their beauty is worth the effort.
Summer annuals require well-drained fertile soil. In areas that are clay and have not been planted, the ground needs to be broken up by a rototiller or by shovel. The organic matter, such as compost, peat moss, soil or other suitable material needs to be thoroughly mixed in the soil. Fertilizer should also be applied according to soil tests. The plants need to be spaced accordingly to provide adequate space for them to grow and spread as well as improve air flow to reduce diseases. An application of a one- to two-inch layer of fine texture organic mulch, such as pine straw, pine bark, cypress mulch or another similar material, will improve the aesthetics of the bed, help keep the soil evenly moist and control weeds. Most require full sun, but a few are shade tolerant.
Apply supplemental water as needed. Check the soil by putting your finger into it one inch to determine how dry it is. For flowering plants, periodic removal of spent flowers, sometimes called deadheading, will encourage the plants to produce more blooms. Most annuals are planted as transplants, but some can be grown from seed.
Many choices are available for summer annuals. Some are known for their colorful flowers. Begonias, which have blossoms and leaves of many colors, can tolerate partial shade. Vinca, sometimes called periwinkles, which should not be confused with the evergreen perennial groundcover plant, produce white and pink flowers. They thrive in hot, dry conditions but will deteriorate if the soil is excessively wet. Celosia, sometimes called cockscomb, produces colorful flowers that vary from convoluted combs to feather-like spikes. They come in multiple colors such as yellow, orange and red, and some varieties have bronze foliage. Marigolds have yellow, orange, red or mixed color blooms that vary in size according to cultivar. Globe amaranth or gomphrena, have small ball-shaped flowers that range from white to pink to purple. They grow up to 18 inches and are tolerant of hot, dry conditions. Petunias one of the most popular annuals planted. They have flowers that come in many colors and thrive in heat although they require adequate moisture.
Moss roses or portulaca are succulents that have a low growing spreading habit that thrives in hot, dry locations. Several colors are available, and the varieties come in single and double flowers. Salvia has large spikes of flowers of many colors, such as white, orange, yellow and cream, and range in size from 10 inches to 30 inches. The perennial blue salvia is sometimes grown as an annual. Zinnias are quite versatile and come in many sizes and colors. They can tolerate hot weather but need to have soil that has ample moisture.
A few annuals are prized for their foliage. Coleus has multi-colored leaves that come in many varieties. Some have deeply lobed or cut margins. Remove the flower spikes as they appear to keep the plants healthy and attractive. Dusty miller is a low growing annual that has grey to silver wooly leaves. Yellow daisy-like flowers appear in the summer.
For a splash of color, consider planting some of these annuals in your garden during the summer. Though they require more care, the beauty they bring is worth it. If you would like to learn more, UGA Extension Gwinnett is offering a class on annual and perennial flowers May 23 from noon to 1 p.m. in the second floor conference room in the Gwinnett County Government Annex Building located at 750 South Perry St., Lawrenceville, GA 30046. To register, please go to the following website at tinyurl.com/yy7n39mg class code ANX34501.