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CIR569 Annual Flowers for Florida 1 R. J. Black and B. Tjia2 1. This document is Circular 569, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Reviewed: March 2000. Please visit the EDIS Web site at http://edis.ifas.ufl.edu. 2. R. J. Black, Associate Professor, Urban Horticulture Specialist, and B. Tjia, Associate Professor, Extension Floriculture Specialist, Department of Environmental Horticulture. Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, 32611. The Institute of Food and Agricultural Sciences is an equal opportunity/affirmative action employer authorized to provide research, educational information and other services only to individuals and institutions that function without regard to race, color, sex, age, handicap, or national origin. For information on obtaining other extension publications, contact your county Cooperative Extension Service office. Florida Cooperative Extension Service/Institute of Food and Agricultural Sciences/University of Florida/Christine Taylor Waddill, Dean. Annual flowering plants with their seemingly infinite variety of flower color and plant form fit into almost any landscape situation. They provide that necessary touch of color to an often drab landscape. Annuals planted in containers can add a splash of color to a porch, deck, or patio area. They are also enjoyed as fresh and dry cut flowers and can be a very rewarding hobby. Annuals are plants which are grown from seed, produce flowers and seed, and die in one growing season. Biennials complete their life span within 2 years and perennials last for 3 years or longer. However, certain plants can be annuals, biennials, or perennials depending on the locality or purpose for which they are grown. As used here, the term "annual" will refer to any plant that is grown for one season. Annuals are especially valuable in Florida. Many of them bloom during winter months, contributing splendidly toward a colorful landscape and producing blooms for home decorations. Other annual species grow and flower during the trying months of June, July. August, and September, persistently blooming through the heat and heavy summer rains. Culture of annuals in Florida is different from that in most states because Florida has three climatic regimes. During winter, nights are cool with an occasional freeze in central and south Florida and frequent freezes in north Florida. In early spring and late fall, nights are cool, whereas high night temperatures, heavy rains. and high relative humidity are typical during summer and early fall. Careful attention must be given to these climatic regimes if annuals are to be grown successfully in Florida. Petunias, pansies. and snapdragons that grow well and flower under cool night temperatures [45-65F (6-18C)] should be planted in the fall, winter, and early spring. Annuals such as marigold, gazania, amaranthus, celosia, crossandra, and coleus that can tolerate high temperature and humidity should be planted in late spring or early summer. Some annuals such as wax begonias and salvias grow relatively well during both hot and cool seasons and can be planted year round in central and south Florida. Florida's winter temperatures in the central and southern portions of the state are often not low enough to kill flowering plants such as geraniums and begonias. Although these plants are perennials and will grow outdoors for several years in mild climates, they should be treated as annuals and replaced with new, vigorous, diseaseand insect-free plants each season. This will eliminate tall, unsightly plants and prevent the buildup of pathogens and insects.
Annual Flowers for Florida 2 While Florida gardeners are fortunate to have abundant sunshine and mild winters, they must contend with infertile sandy soils, insects, and heavy rains which necessitate repeated applications of fungicides for disease control. The addition of annual flower beds in the landscape will increase maintenance tenfold compared to turf. The homegardener should he aware of this and allocate more time for maintenance once the decision is made to grow annuals. Selecting Annuals It is difficult for the average home gardener to germinate seed and grow seedlings; therefore most purchase large seedlings or young plants. Before purchasing annuals, the home gardener should decide how the plants will be used in the landscape. Annuals should serve as an accent to the landscape, not a dominant feature in the setting. Those used in front of the home should harmonize with the setting, and colors should blend with each other and with the home. Large elaborate annual displays are usually too distracting for this area and are best used in the backyard. When selecting annuals for beds or borders, it is best to limit the choice to as few kinds as possible. Combinations of many flower colors and plant forms can distract from the overall appearance of the display. Attractive flower beds can be created by using one plant species. Flower beds should be prepared before plants are purchased. Allowing plants to remain in their original containers for prolonged periods after purchase can have a negative effect on their performance after planting. Purchase plants when you're ready and plant them as soon as possible, preferably within twenty-four hours. After beds are prepared and the kinds and quantity of annuals to be planted are determined, purchase good quality plants. Look for young, healthy, diseaseand insect-free plants with dark green foliage. It is not necessary that plants are in bloom when purchased. If plants reduced in price for sale have been subjected to water stress, are tall and spindly, or have nutrient deficiency symptoms, they are certainly not a bargain and should not be purchased. Plants that have been improperly maintained or held too long seldom recover, and if they do, they will never reach their full potential. This is true especially with snapdragons, pansies, celosias, and zinnias. Seasonal adaptation should be considered when purchasing annuals. Cool-season annuals such as snapdragons and pansies that do well during winter are poor selections when purchased in March or April. To help select the correct annual for a particular season, consult Table 1. Selection of annuals should be greatly influenced by the available light in an area. Some annuals, such as marigold and ageratum, perform best in full sun. Others, such as impatiens and dahlia, grow best in areas receiving several hours of morning or afternoon sun. There are no flowering annuals that will perform well under heavy shade. However, annuals such as crossandra and tuberous begonia grow best in areas receiving no direct sunlight. Optimum and acceptable light levels for many annuals are presented in Table 1. Site Preparation Annual planting sites should be spaded or tilled at least six inches deep several weeks before planting. Florida's sandy soils have very low nutrient and water holding capacities. Incorporation of 2 to 3 inches of organic matter into planting beds will increase nutrient and water holding capacities of these soils. Organic materials such as leaf mold or peat should be thoroughly mixed into the soil. Garden soils, especially in recently developed areas, are frequently infertile Flower beds should be fertilized prior to planting or at planting time and repeated on a monthly basis. Apply 6-6-6 or a similar complete fertilizer at the rate of 2 pounds (908 g) per 100 square feet (9.3 m2 ) of bed area. Application rates for higher analysis fertilizers are presented in Table 2. Controlled release fertilizers are ideal for Florida's sandy soils. Plants usually grow much better with a continuous nutrient supply and labor is reduced since controlled release fertilizer application frequency is less than for rapid release fertilizers. Controlled release fertilizers can be incorporated uniformly throughout the soil before planting and applied on the soil surface of established plantings (Table 3).
Annual Flowers for Florida 3 Annuals can be damaged by nematodes. These micropscopic worms are present in most soils in Florida and are likely to reach damaging levels where susceptible annuals are grown repeatedly. Treating annual beds with a soil fumigant is highly desirable prior to planting, especially if high levels of nematodes are known to be present in the soil. Fumigation will also help to control weeds and soilborne fungi. For information on selection and use of soil fumigants, contact your local County Extension Office. Planting and Care Annuals purchased in compartmentalized plastic flats usually have pot-bound root systems. If planted intact, the root svstem will be slow to establish in the surrounding soil and plants will suffer moisture stress. A preferred method is to lossen and untangle the root system without breaking the soil ball. Plants will usually recover rapidly and become established quickly. Tall and spindly plants should be pruned to half their original size to produce more attractive plants with more flowers. Spacing of plants in a bed should be based on the mature size of a particular plant become established. Weeds should be controlled either by hand weeding or mulching. Black plastic mulches should never be used except when a layer of organic mulch such as woodchips or pine bark is added on top of the black plastic. Temperatures of 117-119F (47-48C) have been recorded 1 to 3 inches above uncovered black plastic mulches. The addition of organic matter over the plastic reduces heat absorption and masks the artificial appearance of black plastic. Mulching materials should not come in contact with plant stems. The high moisture environment created by mulch increases the.chances of stem rot which can result in plant death (Figure 1). Some annuals such as petunias develop yellow leaves (chlomsis) when mulched with cypress or pine bark. This condition is not due to a nitrogen deficiency and cannot be corrected by the addition of fertilizer. Figure 1 Another approach to the culture of annuals in Florida is to grow them in pots. In areas where the soil is very poor or where tree roots limit growth, it is easier to plant small plants into inexpensive plastic pots filled with good soil and place the pots into flower beds. Sink pots into the soil until the top surface of the pots is at soil level. In addition to growing annuals where normally they won't grow, growing annuals in pots eliminates nematode problems, reduces water and fertilizer usage, and allows for easy replacement of plants in the flower bed. Pests and Diseases Annuals have insect and disease problems, and to maintain healthy and attractive plants these problems must be recognized and control measures initiated. The best method of reducing insect and/or disease problems is to keep the plants growing vigorously and free from stress. Cultural practices that should help to reduce insect and disease problems are as follow: (1) select a planting site which provides desirable growing conditions for a particular annual; (2) avoid planting in corners where light intensity and air circulation are minimal; (3) keep plants growing vigorously by following a regular fertilization and irrigation schedule; (4) avoid frequent wilting since water-stressed plants are more susceptible to infestation by thrips and red spider mites; (5) remove spent flowers from plants such as marigold, salvia, snapdragon, and geranium, which do not naturally fall from the plant; (6) prevent pathogenic fungal spores from germinating by keeping water off plants as much as possible and providing good air circulation around plants by allowing ample space between plants at planting; and (7) remove weeds from flower beds since they are frequently host to insects and/or disease organisms. Annuals should be monitored frequently for insects and diseases. Infestations detected in the early stages can be controlled before the entire flower bed is
Annual Flowers for Florida 4 infested. An insect infestation on a few plants can be controlled by picking insects off by hand or in the case of disease, by removing infected leaves. For severe infestations, chemical control will be needed. Contact your local County Extension Office for recommendations on selection and application of pesticides.
Table 1. Annual Flowers for Florida 5 Table 1. Annual flower planting guide. Exposure North Florida* Central Florida South Florida Name Full Sun SunA.M. or P.M. No Direct Sun Cold Tolerance Planting Date Removal Date Planting Date Removal Date Planting Date Removal Date Spacing (Inches) Ageratum XX Tender Mar. 1-15 Aug. Feb.15-Mar. 15 July Feb. 1Mar. 1 June 10-12 Alyssum XX Tender Mar. 1-15 July Feb. 15Mar. 15 July Oct. 1-15 Feb. 1Mar. 1 Mar. June 6 Amaranthus XX Tender Mar. 15-30 Sept. Mar. 15-30 July July-Aug. Mar. 1-15 First Frost July 14-18 Asters XX Tender Mar. 1-15 July Feb. 15-28 June Oct.-Feb. June 12 Baby's Breath XX X Hardy Feb.15-Mar. 15 June Feb.-Mar. June Aug.-Dec. Mar-Apr. 12 Balsam XX X Tender Mar. 15-30 Aug. Mar. 1-30 July Mar. 1-30 June-July 8-12 Begonia(Nonstop) XX X Tender Mar. 1-15 June Feb. 15-28 May Nov-Mar. May 12-14
Annual Flowers for Florida 6 Table 1. Begonia(Thberous) X XX Tender Mar. 1-15 June Feb. 15-28 May Oct.-Jan. Apr. 12-14 Begonia (Wax) XX X Tender Mar. 15-30 Sept.-Oct. Feb.15-28 Sept. Sept.-Nov. Aug. 12-14 Browallia XX X Hardy Mar. 1-15 Aug. Feb. 15-28 Aug. Oct.-Feb. Aug. 12 Calendula XX Hardy Feb.-Mar. June Nov-Feb. June Jan.-Mar. May 8-10 Carnation (China Doll) XX Hardy Nov.Feb.28 June Nov.Feb.28 May Oct. -Jan. 15 Apr. 8-10 Celosia XX Tender Mar.15July Seed Set Mar-July Seed Set Feb.Sept. Seed Set 14 Coleus X XX Tender Apr.-Aug. Oct. Apr.-Aug. Oct.-Nov. MarSep1. First Frost 18-24 Calliopsis XX X Hardy Mar.-May First Frost Mar.-May First Frost Feb.-June First Frost 12 Cosmos XX Tender Mar. 15 Aug. Feb. July Nov-Feb. June 12-14 Crossandra XX XX Tender May-July Oct. Apr.-July Oct. Mar-Aug. Nov. 8-12
Annual Flowers for Florida 7 Table 1. Dahlia X XX Tender Mar. 1530 Aug. Mar. 1-15 Aug. Sept.Dec. July 18-20 Dianthus XX Hardy Feb. July-Aug. Feb. July Oct.Feb. June 10-12 Digitalis (Foxglove) XX X Hardy Sept.Dec. July Sept.Dec. July not recommended 12 Dusty Miller XX X Tender Feb.-Apr. Sept. Feb.-Apr. Aug. Oct.-Mar. Aug. 12 Exacum XX XX Tender Mar.-July When overgrown Mar-July When overgrown Feb.-Oct. When overgrown 12 Gaillardia XX X semiHardy Mar.-May Aug. Mar-May Aug. Feb.-May Aug. 12-18 Gazania XX Tender Mar.-May Nov. Feb.15May Nov. Nov.-May Nov. 8 Geranium XX X Tender Mar.-Apr. July Feb.-Mar. July Oct.-Mar. June 16-30 Hollyhock (Althaea rosea) XX X Hardy Mar. 15June First Frost Feb.15July First Frost Aug.Sept. First Frost 12 Impatiens XX X Tender Mar.15July First Frost Mar. 1July First Frost Sept.June First Frost 8-12 Kalanchoe XX X Tender May-July First Frost MaySept. First Frost Sept.Dec. First Frost 12
Annual Flowers for Florida 8 Table 1. Lobelia XX X Tender Mar. 15Apr. Aug. Feb.15Apr. Aug. Sept.Feb. July 6-8 Marguerite Daisy XX Tender Feb. 15Apr. June-July Feb.-Apr. June-July Oct.-Feb. June 12-14 Marigold XX Tender Mar.15May 3-4 months after planting Mar.Aug. 3-4 months after planting Feb-Dec 3-4 months after planting 8 24 Nicotiana XX X Tender Mar.15July Aug.Sept. Mar. 1-July Aug.Sept. Feb.-May Aug.-Sept. July-Aug. Apr.-May 16-24 Ornamental Pepper XX Tender Mar.-July Oct. Mar.-July Oct. Mar.Aug. Nov. 8-10 Pansy XX Hardy Oct.-Feb. June Oct.-Feb. May Oct.-Jan. Apr. 10-14 Pentas XX X Tender Mar.-May Leaf disease Mar.-May Leaf disease All year Leaf disease 12-14 Petunia XX X Hardy Oct.-Feb. May-June Oct.-Feb. June Sept.Feb. May 12-18 Phlox XX Hardy Mar.-Apr. Aug. Mar.-Apr. Aug. Feb.-Mar. July 8-14 Portulaca (Rose moss) XX Tender Apr.-July First Frost Apr.-July First Frost Mar.Aug. First Frost 10-12
Annual Flowers for Florida 9 Table 1. Rudbeckia XX Hardy Mar.-Apr. Aug. Mar.-Apr. Aug. Feb.-Mar. July 15-18 Salvia XX X Tender Mar.15Aug. When deteriorated Mar. 1-Aug. When deteriorated Feb.15Dec When deteriorated 8-12 Shasta Daisy XX X Hardy Oct.-Dec. July Oct.-Dec. July not recommended 12 Snapdragon XX X Hardy Oct.-Feb. June Oct.-Feb. May Nov-Feb. Apr.-May 10-15 Statice XX Hardy Feb. 15 June Dec.-Jan. June Sept.-Jan. May 8-10 Strawflower XX Tender Mar. 15 Aug. Feb. July Nov.-Feb. June 12-14 Streptocarpus XX X Tender Mar.-Apr. June Mar.-Apr. June Feb.-Mar. May 10 Sweet Williams XX X Hardy Mar-Apr. Aug. Mar-Apr. Aug. Feb.Mar. May 10-12 Thunbergia (alata) XX X Tender Mar.-May First Frost Mar.-May First Frost Feb.-Apr. First Frost 8-10 Torenia XX X Tender Mar.15June Leaf yellowing Mar.1June Leaf yellowing Feb.-Oct. Leaf yellowing 12-18
Annual Flowers for Florida 10 Table 1. Verbena XX Hardy Mar.1May When undesired Feb.15May When undesired Feb.-Apr. Sept.-Nov. When undesired 12 Vinca (Catharanthus) (periwinkle) XX X Tender Mar.-July When undesired Feb.15July When undesired All year When undesired 12 Zinnia XX Tender Mar.-June Leaf disease Mar.-June Leaf disease Feb.-Mar. Aug.Sept. Leaf disease 12-15 Several plants in this table are perennials but may be grown as annuals. Exposure: X = acceptable performance; XX = optimum performance. *North Florida Pensacola to Jacksonville and south to Ocala. Central Florida Leesburg south to Punta Gorda and Fort Pierce. South Florida Stuart to Fort Myers and south to Homestead.
Table 2. Annual Flowers for Florida 11 Table 2. Suggested fertilizer application rates for annuals Fertilizer Analysis lbs/l00 sq. ft. 6-6-6 2.0 8-8-8 1.5 10-10-10 1.2 12-4-12 1.0 12-12-12 1.0 15-30-15 0.8 16-4-8 0.8 16-8-24 0.8 20-20-20 0.6 25-5-20 0.5
Table 3. Annual Flowers for Florida 12 Table 3. Suggested controlled release fertilizer application rates for annuals. Osmocote 14-14-14 Last 2-3 mo. Sierrablen Nursery Mix + Iron 19-6-10 Last 4-5 mo. Osmocote 18&12 Last 4-5 mo. New Plantings 100 ft2 of bed incorporated 4" deep 4 to 5 lbs. 6 to 7 lbs. 7 to 8 lbs. Established Plantings 100 ft2 of bed surface applied 5 to 7 lbs. 6 to 7 lbs. 7 to 8 lbs. 6" standard or azalea pot 1 teaspoon (level) 1 teaspoon (level) 1 teaspoon (level) 1 gallon can 1 teaspoon (heaping) 1 teaspoon (heaping) 1 teaspoon (heaping) 2 gallon can 2 tablespoons (level) 1 tablespoon (heaping) 1 tablespoon (heaping) 3 gallon can 2 tablespoons (heaping) 2 tablespoons (level) 2 tablespoons (level) NOTES: The above rates are maximums. Do not exceed these recommendations. The above rates should be reduced when a build-up of salinity occurs as a result of infrequent or light irrigation, poor drainage, or high salinity levels in irrigation water. To simplify information in this publication, trade names of products were used. No endorsement of these specific products is intended nor is criticism implied of similar products which were not mentioned.