By the time August arrives in the Northern Hemisphere, many garden plants may have passed their prime. Spring and early summer perennials often go dormant by August. Annuals trying to set seed can also look quite discouraged. Revive your late summer garden with flowers that are in season in August. Some of them will start the month in flower. Others will have their first blooms in August and continue to provide garden color until frost.
Native to Brazil, calico flower (Aristolochia littoralia) is an 8-to-20-foot vine. Evergreen where winter-hardy--to 20 degrees Fahrenheit--it grows as an annual or container plant in colder climates. This rapid spreader has heart-shaped, 3-to-4-inch shiny leaves with pale green surfaces and greenish-gray undersides. Bruised foliage emits an unpleasant scent, according to the Missouri Botanical Garden. From July to September, the vine produces unusual, purple-mottled white flowers similar to curved pipes. In-ground plants need a fence, trellis or other support. Give calico flower consistently moist, well-drained fertile soil and a sunny to partly shady location. Cut back on water in winter.
Summer hyacinth (Galtonia candicans) is a bulb plant hardy to minus 10 degrees Fahrenheit. Native to Southern Africa, it stands from 2 to 4 feet high. Up to 3 feet wide, plants have basal clumps of 2-to-3-foot, strap-shaped green leaves. In August and September, summer hyacinth has upright stem spikes of white, fragrant trumpet-shaped blooms. Resembling gladioli, they work well in cut flower arrangements. Plants may suffer attacks from slugs or snails.
Plant summer hyacinth, advises the Missouri Botanical Garden, during the spring. Place the bulbs 5 to 6 inches deep and 6 inches to 1 foot apart. Give them full sun or partial shade and moist, rich well-drained soil. Provide deep winter mulch at the colder end of their hardiness range.
Another bulb, autumn crocus (Colchicum autumnale) tolerates temperatures as low as minus 30 degrees Fahrenheit. Standing 3 to 6 inches tall and wide, it has dark green, lance-like spring foliage that dies back by mid-summer. Flowering stems--without leaves--appear in August. They have cup-shaped, 3-inch flowers of pink, lilac or purple. Relatively insect-and-disease-free, autumn crocus may develop bulb rot in poorly-drained drain soil. It's also vulnerable to snails and slugs.
Use the crocus, recommends the Missouri Botanical Garden, to replace declining spring and summer blooms. Plant the bulbs in summer to flower the same year. Place them 3 inches deep and 6 inches apart in full sun to partial shade and averagely moist, well-drained soil.