The plants listed below are generally grown as annuals. In climates where winters tend to be mild, they may be grown as perennials.
Snapdragons (Antirrhinum) offer a rainbow of colors for the spring garden. Named for the flower's resemblance to the mythological dragon, snapdragons can be planted during the spring and will withstand a light frost, as long as temperatures do not remain below freezing for very long. Dwarf, medium and tall varieties are available, and colors range from pure white to dark hues and bicolors. Purchase plants at your favorite garden center, or start snapdragon seeds indoors under lights or on a bright, sunny windowsill 8 to 10 weeks before your anticipated planting date.
Stock (Matthiola incana) offers a heady, spicy fragrance that resembles cloves, bright flowers, and green, needle-like foliage. It can be grown as a perennial in some areas, but most gardeners treat stock as an annual plant. Stocks bloom starting in mid spring and continue until the very hot weather of the summer months. They grow up to three feet tall, and are available in a wide range of colors including white, cream, yellow, red, pink, purple and all shades in between. Stocks are great container plants as long as adequate drainage is provided; they dislike too much water.
Also called "pot marigold," Calendula officianalis has a long and revered history as a medicinal and dye plant. Calendula can be easily grown from seeds, and offers white, yellow and orange flowers on medium-height plants. It produces profuse blooms in cooler weather, and can be treated like a perennial plant in warmer climates.
Petunias offer bright, cheerful flowers, some cold tolerance, and a pleasant fragrance. They also attract bees and hummingbirds, and offer food sources to these creatures at a time when food may be scarce. Multiflora, grandiflora, wave and other types of petunias offer a wide range of choices for your landscape. Wave petunias are especially beautiful as ground covers, window box plants, and container plants as they cascade over the sides of the container into large drapes of flowers. Petunias thrive in cool, but not cold weather, so be sure to save petunias for the tail-end of your cool weather season.
Sweet alyssum truly lives up to its name. The low-growing plants exude a delicate perfume on a warm spring day. They grow only about four to six inches high, but spread out, creating a carpet of flowers. Sweet alyssum can withstand cool spring temperatures, and can be planted as soon as the soil can be worked. Start seeds indoors several weeks before the last frost date, or purchase plants from your local garden center. Plant in full sun in well-drained soil; in areas with hot summers, partial shade is recommended to keep them blooming throughout the growing season.
In addition to these beautiful cool-flowering annuals, how about adding cool-season blooming perennials to your flower garden? Perennial dianthus, like stock, offers a sweet, clove-like scent. Phlox is an excellent ground cover that blooms as soon as the really cold weather ends, and attracts the first butterflies of the season. Candytuft is also an excellent ground-cover plant, and offers a carpet of white blossoms for several weeks at a time. By interspersing cool-season annuals among your perennials, you can enjoy a profusion of color for many weeks until you can plant your warm0season flowers.