SPECIAL TOPICS: BULBS

BULB MANAGEMENT

Bulbous plants are susceptible to damage by many diseases and pests. The most difficult diseases to control are insect-transmitted viruses. The only treatment for virus is to destroy infected plants and to control insect vectors. Major damage is caused by:

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 Poor drainage, soil borne bacteria and fungi. Spraying with a bactericide or fungicide may be helpful if the damage is not too severe.
• Chlorosis or yellowing of bulb foliage caused by lack of nitrogen, iron, zinc, magnesium or manganese. Publications on adjusting soil pH and correcting nutritional disorders can be obtained from your local county extension office.
• Insects directly damage bulb plants and allow disease organisms into plant tissue.
• Aphids spread virus diseases. Complete control is essential for bulbous plants such as tulip, calla lily, dahlia, gladiolus, hyacinth and iris, which are adversely affected by virus diseases.
• Thrips feed by rasping soft plant tissue and sucking plant fluids causing brown spots on petals and preventing buds from opening.
• Spider mites cause injury similar to that of sucking insects as they feed on the leaves of bulbous plants during warm, dry periods. Bulb mites are particularly damaging to bulbs of amaryllis, gladiolus, hyacinth, lilies, daffodil and tulip.
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Mealybugs are insects covered with a white, waxy material. Some control can be obtained by frequent syringing with a hose.
• Many bulbous plants are damaged by microscopic, transparent, wormlike animals called nematodes. Nematodes feed on the roots and may cause disintegration of the basal plate of some bulbs when present in sufficient numbers.

When pest infestations are severe or where large numbers of plants are involved, chemical control may be needed. For recommendations on selection and application of insecticides, contact the agricultural extension agent in your county.

Animals such as moles, pocket gophers, rabbits and squirrels can damage bulbs and bulb-like structures. Trapping is probably the most effective control for these pests. Repellents may keep rabbits away when used as directed.

The informality of most south Florida gardens means that bulbs are normally used in small groups among shrubs or herbaceous ground covers rather than in beds by themselves. This makes it difficult to treat the soil against nematodes and means that the most popular and successful bulbs are those that thrive under the same cultural treatment as the rest of the plants in the bed.

Most of the bulbs familiar to northern gardeners are not satisfactory in south Florida. Even when bulbs are brought in from cool regions and given the necessary cold treatment to induce blooming, the flowers will be very short-lived and often smaller and less brightly colored than usual.

 
For more information and charts go to: http://edis.ifas.ufl.edu/MG029
Bulbs for Florida. R. J. Black, N. C. Bussey and D. Burch.Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Publication date: June 1990. Revised: March 1994, October 2003.

 

BULBS FOR FLORIDA

Florida gardeners can choose from a wide variety of bulbous plants that will thrive and produce beautiful flowers year after year with proper care. Florida's climate is favorable for growing many tropical and subtropical bulbous plants. The number of bulbous plants is so great that the choice is not always simple. Unfortunately, many of the common bulbs of northern states such as tulips, hyacinths, and some irises and lilies do not grow well in Florida. Recovering bulbs for planting the following year is not recommended because the bulbs rarely flower again.

In general, most bulbs thrive in a sunny location. However, some, such as caladiums, do best in partial shade. Heavy shade should be avoided because it will cause thin, spindly growth and poor foliage color and flowering. Bed preparation is important for a successful bulb crop. A well-drained soil is the first thing to be considered. Weeds can be controlled by spreading a 2” layer of mulch over the bed at planting time.

General care includes fertilization once or twice during the growing season with a special bulb fertilizer. Bulbs such as tulips and hyacinths that are usually discarded after flowering need not be fertilized since they have enough stored food to last through the blooming period.

It is important that plantings do not suffer for lack of water during times of growth and flowering. Digging and replanting usually encourages more uniform flowering and larger flowers. To reduce the chance of insect and disease damage, a combination of fungicide and insecticide dust may be applied.

True bulbs (amaryllis, hyacinth, narcissus) develop miniature bulbs, known as bulblets, which, when grown to full size, are known as offsets. Offsets can be separated from the mother bulb and replanted into beds. Some bulbs such as amaryllis, blood lily, hurricane lily and spider lily can be cut into several vertical sections and each section planted upright in a mixture of equal volumes of sand and peat. Corms, such as gladiolus and watsonia, produce new corms on top of the old corms. These can be separated from the mother corms and stored along with the new corms over winter for planting in the spring. New corms usually produce flowers the first season, but cormels require 2 or 3 years of growth to reach flowering size.

Tubers (caladium, gloriosa), tuberous roots (dahlia, ranunculus) and rhizomes (canna, day lily) are propagated by cutting them into sections, each containing at least one bud. Special care should be taken when dividing dahlia tuberous roots to ensure that each tuberous root has a piece of crown bearing a healthy bud. Tuberous roots that are broken off without a bud are worthless.

 
For more information and charts go to: http://edis.ifas.ufl.edu/MG029
Bulbs for Florida. R. J. Black, N. C. Bussey and D. Burch.Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Publication date: June 1990. Revised: March 1994, October 2003.