Annual plants are those that sprout, flower, set seed and die in a single gardening season. The hardiest summer annuals are those that stand up to various summertime conditions, such as drought, wind and extremely hot weather with only a reasonable quantity of attention in the gardener. Features like self-seeding, which efficiently perennialize the plants, are a great asset too. A range of annuals are extremely summer-hardy, with picks available for sunny or shady conditions. Knowing your soil type (heavy clay or sandy loam, as an example) is also a significant factor in plant selection.
Some of the best summer annuals are sun lovers like French marigolds (Tagetes patula). Low-growers that bear heavy clay soil and are usually ignored by deer, marigolds bloom repeatedly throughout the summer in hues of yellow, orange and gold. Easily grown from seed or young transplants, French marigolds grow between 6 and 12 inches tall. Shirley poppies (Papaver rhoeas Shirley Group) are also ignored by deer and develop rapidly to 24 inches tall. Shirley poppies bloom in colors of white, rose, red or red and often reseed.
Related to perennial delphiniums, larkspur (consolida ajacis) provides spires of blue, blue-purple, white or pink from ancient to mid-summer. Growing 2 to 4 ft tall, the plants feature distinguishing spurred flowers and may be deadheaded to prolong bloom. If not deadheaded in the end of the flowering period, larkspur will self-seed readily. A little shorter at 1 to 3 feet tall, but equally amenable to self-seeding, annual cornflower or bachelor’s button (Centaurea cyanus) blooms in early summer. The blooms are bright blue and vigorous. Cornflower continues to be reported as invasive in some locations.
Poor Soil Lovers
Some of the best summer annuals thrive in poor, lean soil. Nasturtiums (Tropaeolum group) are usually low-growing plants, but are also accessible cascading or scaling forms. The funnel-shaped flowers bloom in single and bi-colored mixtures of white, cream, yellow, yellow and crimson. Nasturtiums also bear rounded, blue-green leaves. The plants blossom abundantly in sunny situations with free-draining dirt. Moss rose (Portulaca grandiflora) also thrives in poor, dry land, bearing thin, succulent leaves and rose-like blooms in every colour except true blue. The plants are low-growers, reaching only 9 inches tall with a 12-inch spread.
Some of the best summer annuals also thrive in colour. With purple, blue-purple, yellow or bi-colored blooms, wishbone flower (Torenia fournieri), requires only consistently moist soil. The crops, which bear oval-shaped leaves, grow to 12 inches tall, with a nearly equal spread. Another partial shade stalwart is the bedding begonia (Begonia Semperflorens Cultorum Group). Though the plants are perennial in U.S. Department of Agriculture plant hardiness zones 10 and 11, they are grown as annuals in much of this U.S.. The rounded leaves are waxy and the small flowers bloom in hues of pink, white and red.