2010

Caring for Spring-flowering Bulbs & Planting Summer Bulbs

Narcissus and canna
April includes both the full flowering of spring bulbs such as daffodils and the planting season for summer bulbs like cannas.
Karen Russ, ©2007 HGIC, Clemson Extension

Karen Russ
Home & Garden Information Center

Sometime this month or in early May, depending on where you live in South Carolina, spring-flowering bulbs will finish blooming, and it will be time to plant summer bulbs.

If you have not fertilized your permanent spring-flowering bulbs this year, apply 1 to 2 pounds of 10-10-10 per 100 square feet. Ideally this should be done as soon as shoots appear in the spring, but if the foliage is still growing, your bulbs can still benefit. Healthy, robust foliage produces carbohydrates that are stored in the bulb for the next growing and blooming season. Repeat this application in the fall when newly growing roots can take up nutrients.

Do not remove the leaves of spring-flowering bulbs until they turn brown, and do not tie leaves into bundles. The leaves are necessary to produce the carbohydrates that are stored in the bulb for next year's bloom. If you object to the appearance of yellowing leaves, try inter-planting bulbs with perennials or summer annuals for camouflage. Daylilies and moderate-sized ornamental grasses are particularly good for hiding aging bulb foliage. Be careful not to dig so deeply as to damage the bulbs.

daffodils
Remove old daffodil flowers once they wilt, but do not remove leaves until they are fully brown.
Karen Russ, ©2009 HGIC, Clemson Extension

Remove flowers of tulips and daffodils after they fade to prevent seed formation. This allows more carbohydrates to be stored in the bulbs. However, with a few exceptions, tulips rarely rebloom the following year in South Carolina, particularly in areas below the Upstate.

While most tulips will not return each year in South Carolina, Lady Tulips (T. clusiana), a small species tulip, will become perennial in the southeast. Pictured is the cultivar 'Cynthia.'
Karen Russ, ©2009 HGIC, Clemson Extension

Many bulbs eventually become overcrowded and must be divided and replanted for best effect. Wait to dig bulbs until after the foliage has turned yellow and withered. Divided bulbs can be replanted immediately or stored in a cool, dry area for replanting in the fall. Discard any bulbs that appear soft or diseased.

Now is a great time to review your spring bulb plantings and plan what you want to add this coming fall. Spring-flowering bulb catalogs for fall 2010 are already beginning to appear.

Just as spring-flowering bulbs start to disappear, the time to plant new summer-and fall-flowering and foliage bulbs begins. They should be planted in the spring after the danger of frost is past. The soil temperature should be at least 55 °F as bulbs planted in cooler soils may rot before they can sprout.

Canna blooms
Cannas are polular and reliable summer-flowering bulbs that offer both foliage and flower color. Above is the cultivar 'Tropical White.'
Karen Russ, ©2007 HGIC, Clemson Extension

Many summer-flowering bulbs that must be stored through the winter in northern states will be cold-hardy and can be planted permanently in South Carolina. These include dahlias, lilies, cannas, gladiolus and many others. Gladiolus and dahlias may not be fully hardy in the mountains. Elephant ears vary by variety and species in cold hardiness, although many will over-winter well even in the upstate if adequately mulched.

Many elephant ears, including Colocasia esculenta var. antiquorum 'Illustris' are hardy even in the Upstate.
Karen Russ, ©2005 HGIC, Clemson Extension

Caladiums and tuberous begonias are not hardy and will need to be replanted each year, although they can be dug in the fall and stored for the next season. Caladiums also need warmer planting temperatures. The soil temperature at planting should ideally be 70 °F. A good rule of thumb in determining when to set out caladiums is to plant them when you plant okra seed in the vegetable garden.

For more information on caring for and selecting spring-flowering bulbs, see HGIC 1155, Spring-Flowering Bulbs. For more information on summer bulbs, see HGIC 1156, Summer- & Fall-Flowering Bulbs. For information on growing tuberous begonias and caladiums, see HGIC 1159, Begonia and HGIC 1160, Caladium.

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This information is supplied with the understanding that no discrimination is intended and no endorsement by the Clemson University Cooperative Extension Service is implied. All recommendations are for South Carolina conditions and may not apply to other areas. Use pesticides only according to the directions on the label. All recommendations for pesticide use are for South Carolina only and were legal at the time of publication, but the status of registration and use patterns are subject to change by action of state and federal regulatory agencies. Follow all directions, precautions and restrictions that are listed.