Summer- and Fall-Flowering Bulbs

Summer- & fall-flowering bulbs add beauty and interest to the landscape. They have exciting forms, fragrances and colors that other flowers cannot achieve.

Most summer-flowering bulbs like warm temperatures and humid conditions and thrive in South Carolina. Many are hardy here that can not be grown farther north.

Landscape Use

Summer- & fall-flowering bulbs need both plenty of water while growing and well-drained soil. There are summer and fall bulbs that will grow well in sun or shade.

Summer-flowering bulbs should be planted in the spring after danger of frost is past. The soil temperature should be at least 55 °F. Bulbs planted before this temperature is reached may rot before they can sprout.

Some tender summer-flowering bulbs, such as caladiums and tuberous begonias, should be harvested and stored before the first fall frost. Allow the bulbs to air-dry for one to two days and store them in a cool, dry place for planting next spring.

When buying bulbs, always select ones that are firm and blemish-free. Large bulbs produce larger flowers.

Problems

Viruses can occur in all bulbs. Variegation may occur in the flower, yellow streaks may develop in the leaves, and plants are generally smaller and weaker. Destroy all infected plants as they appear, and control all sucking insects that can transmit viruses.

Aphids and thrips are common and may cause young leaves to show puckering, curling or other abnormalities.

Common Summer & Fall Bulbs

Dahlias (Dahlia species): Flower of dahlias occur in virtually every color except clear blue and range from less than an inch across to blooms the size of dinner plates. Many shapes and colors are available. Plants grown from seeds will not grow true to type. Buy tuberous roots and save the roots each year for named cultivars. Plants normally bloom from midsummer until frost.

Dahlias prefer full sun and a rich, well-drained soil. Large-flowering dahlias should be spaced 3 to 4 feet apart; smaller dahlias can be spaced 2 feet apart. Keep them actively growing for best results with ample water and fertilization. Fertilize monthly with a water-soluble fertilizer or apply 2 to 3 pounds of 5-10-10 or 10-10-10 per 100 square feet in July. Pinch out the tips of the main stems three weeks after planting to produce strong, bushy plants. Take off the faded blooms during the summer months to encourage continuous blooming. Tall dahlias will need staking.

Cover the plants with 3 to 4 inches of loose mulch in colder parts of South Carolina for winter protection. Divide clumps in the spring so that each section has at least one shoot. The best time to divide is after the eyes have sprouted and the new growth is no more than an inch in length.

The most common pests are aphids, spider mites, leafhoppers, thrips and European corn borers. Disease problems include tuber rots, mosaic virus, powdery mildew and Botrytis blight.

Gladioli (Gladiolus species): Often grown as cut flowers: “glads” offer a wide array of colors. The plants grow and flower best in full sun and moist, well-drained soil. Soils that produce good garden vegetables will produce good glads.

Space planting times a week or so apart to have gladiolus in bloom the entire summer. Plant the corms 3 to 6 inches deep, depending on size of corm. Glads can be planted by digging out a trench and planting corms in either a single or double, staggered row. Corms may be spaced only 2 to 3 inches apart in the row. Rows should be spaced from 20 to 36 inches apart.

Glads need ample water throughout the growing season. Watering should soak the ground thoroughly. Avoid daily light watering. Fertilizer (5-10-10) should be applied at the rate of 3 to 4 pounds per 100 square feet of bed area when plants are 6 to 8 inches tall, and again when the flower spikes appear. To keep the plants erect, they must be staked. Hilling up soil on both sides of the row also gives good support. Mulches help to keep down weeds and conserve soil moisture. A 3- to 4-inch depth is needed for good weed control.

Cut the flower spike when the first floret is showing color for the best quality cut flowers. Be sure to leave at least two, and preferably four, leaves on the plant after cutting spikes to help corms mature properly.

Gladiolus will overwinter with a layer of mulch in most of South Carolina. If you want to store the corms, dig them after the tops die off, but before a hard freeze. Dry outside in a light, airy place. After two to three weeks of drying, remove the old withered corm from the base and discard. Corms should be stored during the winter at a temperature of 35 to 45°F in a well-ventilated area.

The most troublesome pests are gladiolus thrips. This insect does considerable damage to the flowers. It causes malformed and spotted flowers. Aphids, grasshoppers and cucumber beetles are other insect pests that may cause damage to flowers or foliage. Gladiolus corm and stem rots are active during storage and develop with improper curing and storage. Before planting in spring, inspect and discard all infected corms.

Cannas (Canna species): These popular plants have an extended flowering period and luxurious green, striped or bronze foliage. There are many cultivars available in a wide choice of colors including cream, yellow, orange, pink, red, and spotted and striped bicolors. Although most cannas grow 3 to 6 feet tall or more, new dwarf cultivars may reach only 2 feet tall. Cannas bloom from early summer until frost if you remove old blossoms regularly so that they do not set seed.

Cannas love hot summer sun, but need rich soil and a good moisture supply. They are reliably hardy and can be left in the ground throughout the year in South Carolina. Plant the rhizomes 1 to 2 inches deep and 12 to 24 inches apart. You can divide the rhizomes in the spring if you want to increase your plants. Apply 3 to 4 pounds of 10-10-10 per 100 square feet every 4 to 6 weeks throughout the growing season and water thoroughly.

Canna leafrollers and other caterpillars may be destructive on cannas.

Lilies (Lilium species): There are about 80 species and several hundred cultivars of lilies available ranging in height from 2 to 8 feet. Lilies make great cut flowers and provide gorgeous color shows during most of the summer season. They are available in white, yellow, red, pink, orange, maroon and bicolors.

Lilies need well-drained soil in an area that receives sun or part shade. The ideal situation will place the lily flowers and leaves in sun while shading their roots. They need to be kept moist. Lilies can be planted either in the fall or spring, whenever the bulbs are available. Handle the bulbs carefully because the scales can be easily broken off. Space them 6 to 10 inches apart. Plant lilies (except Madonna lilies) with 4 to 6 inches of soil covering the bulb. This allows them to form roots along their stems. Fertilize lilies lightly monthly with 5-10-10, starting when the shoots begin to emerge. Tall lilies should be staked and protected from high winds. Mulch well to keep lily roots cool. Remove blooms when they die to prevent seedpod formation. Cut stems off at ground level after they turn brown, but never cut them down while the leaves are still green.

Easter lilies (Lilium longiflorum) have classic white trumpet-shaped flowers and a heavenly scent. They will thrive in hot coastal climates. They grow from 1½ to 3 feet tall.

Asiatic lilies have straight stems and many brightly colored blossoms ranging from the softest pastels to fiery reds and oranges. They grow 2 to 3 feet tall and bloom over a long season. Most Asiatic lilies are unscented. They prefer cool temperatures and grow best in the Upstate.

Oriental lilies have large, ornate flowers, usually in white, pink, rose or red with intense fragrance. Cultivars vary from 18 inches to 6 feet tall.

They will grow well throughout the state in acid, rich soil.

Madonna lilies (Lilium candidum) bloom with fragrant white flowers on 3-to 4-foot stems in early summer. They should be planted shallowly, unlike other lilies. Their leaves will begin to grow in the fall. They will grow well throughout the south if they are given rich, slightly alkaline soil and afternoon shade.

Trumpet lilies are tall (up to 6′), with large, fragrant flowers in midsummer. They are colored white, gold, pink, apricot or yellow. They prefer cool temperatures and grow best in the Upstate.

Tiger Lilies (Lilium lancifolium) grow happily throughout the state in colors of spotted white, yellow, orange and red. They should be kept apart from other lilies since they can be carriers of viruses.

Additional Summer- & Fall-Flowering Bulbs

Additional Summer- & Fall-Flowering Bulbs (continiued)

Originally published 09/99