Spring gardens, with their bright daffodils and tulips, showy peonies and fragrant clouds of crabapple and dogwood blooms, are tough acts to follow. Gardeners, however, can keep the parade of colorful and fragrant blooms from spring to fall by selecting long-blooming annuals to replace those fading spring performers. These obliging plants grow easily. In the right conditions, they'll provide nearly non-stop garden color from May--or earlier--to September and beyond.
Annual nasturtiums (Tropaeolum) fill gardens with bright warm color from May to September. These bushy to spreading plants grow from one to 10 feet high and up to three feet wide. Their creeping stems have round, green to reddish-green leaves and trumpet-shaped, spurred blooms. Flowers, up to 2.5 inches wide, are available in shades of creamy white, red, orange and yellow as well as bi-colors.
Dwarf nasturtiums include the Alaska series, with variegated, white-splotched green leaves. They make excellent container, rock garden and ground cover plants, according to the Missouri Botanical Garden. 'Jewel of Africa,' a variegated climbing nasturtium for trellises or fences, reaches eight feet in height. Give plants full sun and mildly acidic (pH below 6.8), well-drained soil. Provide afternoon shade where summers are hot. Check for aphids, whiteflies and mealybugs.
Swan River Daisy
The Swan River daisy (Brachyscome), an aster family annual growing up to 18 inches high and wide, blooms from May until frost. A compact, mounding plant, it has greenish gray foliage. Hybrid daisy cultivars have abundant, lavender, white, yellow, blue or purple-rayed (petaled) blossoms in numbers that conceal its leaves. Flowers have yellow to nearly black centers.
Susceptible to snails and slugs, Swan River daisy is largely disease-resistant. Use it, recommends the Missouri Botanical Garden, as an edging or container plant or in rock gardens. Provide full sun and consistently moist, rich well-drained soil. Plants perform best where summers are cool. Cut them back when flowers diminish to promote later blooms.
Garden balsam (Impatiens balsamina), an annual native to southeast Asia and India, blooms from May until frost. Growing six to 30 inches high and up to 18 inches wide, it has an upright habit and cup-like, usually double flowers. The fragrant, spurred blooms may be white, pink red, purple or bi-colored. Largely free of insects and diseases, balsam has pale green, toothed elliptical leaves.
Use this plant as a walkway edging or shady border or bed planting. It likes full sun to partial shade--where summers are hot--and moist, well-drained fertile soil. Pinching back plants when they reach four inches in height will increase their bushiness and bloom.