Enviroscaping to Conserve Energy: Ground Covers for South Florida

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Enviroscaping to Conserve Energy: Ground Covers for South Florida
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Meerow, A.W.
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"Publication date: July 1993. Revised: September 2003."
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"EES-39"

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EES39 Enviroscaping to Conserve Energy: Ground Covers for South Florida1 A.W. Meerow and R.J. Black2 1. This document is Circular EES-39, formerly "Landscaping to Conserve Energy: Ground Covers for South Florida," Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Publication date: July 1993. Revised: September 2003. Please visit the EDIS website at http://edis.ifas.ufl.edu. 2. Alan W. Meerow, former associate professor, REC-Ft. Lauderdale, Institute of Food and Agricultural Sciences; Robert J. Black, professor emeritus, Consumer Horticultural Specialist, Environmental Horticulture Department, University of Florida, Gainesville FL 32611. The Florida Energy Extension Service receives funding from the Florida Energy Office, Department of Community Affairs and is operated by the University of Florida's Institute of Food and Agricultural Sciences through the Cooperative Extension Service. The information contained herein is the product of the Florida Energy Extension Service and does not necessarily reflect the views of the Florida Energy Office. 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. Introduction A ground cover is any low-growing plant that can be used to cover an area in the landscape. Many woody and herbaceous plants fulfill this role. And as part of passive, energy-saving landscaping (enviroscaping), ground covers can provide a surprising amount of residential energy savings during Florida's 5 to 7 months of high temperatures. Plants release water through pores in their leaves by transpiration. As warm air passes over leaf surfaces, heat is absorbed by the water, which then evaporates and lowers the temperature of the air. Called evaporative cooling, this interaction lowers air temperature immediately surrounding vegetation by as much as 9F (5C). The greater the leaf-surface area in the landscape, the greater the cooling effects. Paved surfaces around the home contribute substantially to summer heat loads. These surfaces absorb the sun's heat or reflect it back into the immediate environment, increasing the amount of discomfort experienced by people during the day. Paved areas also store heat during the day, keeping temperatures high around the home even after sunset. Temperatures over ground covers can be 15 to 25F (8.3 to 14C) lower than over asphalt or concrete. Turfgrass Turfgrass qualifies as a ground cover. Many people find great aesthetic appeal in sweeping, well-manicured green lawn. On the practical side, no other plant can withstand as much foot traffic as turf. Maintaining a lawn in prime condition, however, requires energy-intensive mowing, regular fertilization, irrigation, and, at times, expensive pest and disease control. A quarter-acre lawn requires four times the total energy costs of a landscape of the same size that has a one-sixteenth-acre lawn with the remaining area planted in low-maintenance vegetation (Parker, 1982). As fossil-fuel prices rise, so do the costs of fertilizing, watering and mowing a lawn. Some

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Enviroscaping to Conserve Energy: Ground Covers for South Florida 2 turfgrasses, like bermudagrass, do best with 218 pounds of nitrogen per acre per year, a 7.2 million Btu investment. A medium fertilization level of 174 pounds of nitrogen per acre per year (5.8 million Btu) is recommended for St. Augustine lawns. At the lowest fertilizer level, centipede lawns need 87 pounds of nitrogen per acre per year (2.9 million Btu). Choosing centipede instead of St. Augustine can save 29 million Btu of energy (equal to the energy in 232 gallons of gasoline) per acre over 10 years (Whiffen, 1993). On average it takes a quarter of a gallon of gasoline (31,250 Btu) [combustion engine] or 1.4 kwh (15,000 Btu) [electric motor] to mow a quarter-acre lawn. Depending on location and fertilizer frequency, the lawn probably gets mowed 10 to 20 times a year. To minimize energy and time inputs, only cut one-third of the grass blade at a time and don't over fertilize (Whiffen, 1993). Water quality and availability have become important issues in Florida. Depending on location, Florida lawns need 20 to 35 inches of water from irrigation per year. Over 8 million Btu of energy are required to supply water to a one-half-acre lawn in Orlando. If a one-half-acre yard is landscaped so one-fourth is lawn and the rest is planted with ground covers, shrubs and trees in mulched areas, over 4 million Btu of energy can be saved annually along with 224,000 gallons of water (Whiffen, 1993). Alternatives to Turfgrass There are ground covers besides turf that require a fraction of the upkeep and are frequently more adaptable to a wider range of environmental conditions. For instance, turf does not grow well in dense shade and is difficult to establish in extremely wet or dry areas. There are several other ground covers adaptable to such problem situations. Lily turf (Liriope muscari, L. spicata) and mondo grass (Ophiopogon japonicus) are excellent, low-maintenance performers in dense shade. Lippia (Lippia nodiflora) has an outstanding tolerance of wet soils. Golden creeper (Ernodea littoralis), a native seacoast species, is highly tolerant of both salt and drought. Proper selection can minimize irrigation, fertilization and mowing after ground covers are established. Herbaceous and woody ground covers offer a variety of colors and textures in contrast to the uniformity of turf grass. They can unify the home landscape and complement trees and shrubs. Establishment of Ground Covers Generally, ground covers are established in two years, although some species require slightly more or less time. During this period, a regular program of irrigation, fertilization and weed control ensures strong, rapid growth. Mulch aids water retention in new plantings and helps the spread of ground covers that root along their stems. Once established, many ground covers need only an occasional trimming to keep them tidy and within their designated area. Selecting a Ground Cover The accompanying table will help home gardeners and landscape professionals select ground covers appropriate for south Florida site conditions. Each species has the expected height of the mature plant, along with the color of both leaves and flowers. The drought-tolerance ratings refer to Florida conditions only and should be interpreted as follows High: survives without supplemental irrigation after establishment; Moderate: requires supplemental irrigation during very dry periods to maintain satisfactory appearance and health; and Low: little or no drought tolerance. Drought tolerance also varies with soil and other environmental conditions. 'X' indicates whether a particular ground cover can be used in each of five landscape situations. Finally, the "Comments" section has special notes about each species. Turf grass is still the best ground-cover choice for outdoor areas that have heavy recreational use. For situations where turf serves no practical purpose, alternative ground covers perform equally well or better at a fraction of the energy input required by a lawn. References Parker, J.H. 1982. An energy and ecological analysis of alternate residential landscapes. J. Environ. Syst. 11: 271-288.

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Enviroscaping to Conserve Energy: Ground Covers for South Florida 3 Whiffen, H.J.H. 1993. E2& E energy efficiency & environmental news. UF/IFAS Energy Extension Service, Feb., Gainesville, FL.

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Enviroscaping to Conserve Energy: Ground Covers for South Florida 4 Table 1. Groundcover selection for south Florida. Scientific Name Common Name = Native Height Light1 Drought Tolerance Salt Tolerance Under trees Banks & slopes Edging Seaside Open areas Aloe spp. Aloe 12 inches S, PS High High X X X Description: Succulent. Often has bi-colored leaves. Red, orange or yellow flowers in summer. Comments: A number of low-growing species are available. Aspidistra elatior Cast iron plant 20-30 inches Sh Low Moderate X Description: Green foliage (variegated form is available). Comments: Slow growing. Begonia spp. Begonia 6-18 inches PS, Sh Low None X X Description: Wide range of foliage color. Flowers are usually red, white, or pink. Comments: Hundreds of species and hybrids are available, many suitable for ground cover use (the rhizomatous type is best for this purpose). Prefers fertile, moist but well-drained soils. Billbergia spp. Bromeliad 12-18 inches PS, Sh Moderate Low X Description: Leaves are various shades of green, often striped white or silver. There are many variegated forms and hybrids. Flowers are pink and blue. Comments: Vigorous. Some plants form large clumps. B. nutans and B. pyramidalis are common; B. 'Fantasia' is a variegated hybrid. Carpobrotus edulis Hottentot fig, iceplant 6 inches S High High X X Description: Grayish-green leaves. Yellow to rose-purple flowers in summer. Comments: Excellent seaside ground cover and sand binder. Carissa macrocarpa Dwarf carissa 12-15 inches S, PS High High X X X X Description: Dark green leaves. White flowers Comments: Select dwarf cultivars only. Catharanthus roseus Madagascar periwinkle 10-18 inches S High High X X X X Description: Pink or white flowers. Comments: Plants persist for 2 to 3 years, but naturalize readily from seed. Avoid planting in wet areas. *Licania michauxii Gopher apple 3-12 inches S High High X X

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Enviroscaping to Conserve Energy: Ground Covers for South Florida 5 Table 1. Groundcover selection for south Florida. Scientific Name Common Name = Native Height Light1 Drought Tolerance Salt Tolerance Under trees Banks & slopes Edging Seaside Open areas Description: Leaves are dark green above and downy white below. Red fruit in summer Comments: Tolerates poor soils. Chlorophytum comosum Spider plant 12 inches S, PS, Sh Moderate Low X X X Description: Green, or green and white variegated leaves. Comments: Solid green form more vigorous; spreads by runners. Cuphea hyssopifolia Cuphea, false heather 12-15 inches S, PS None None X X Description: Purple to white flowers most of the year Comments: Low, shrubby heather-like habit. Requires moist soil. Cryptanthus spp. Cryptanthus Earth star 2-10 inches Sh Moderate Low X X Description: Leaves are different shades of green to red, often striped. Comments: Prefers shady, moist locations. Cyrtomium falcatum Holly fern 24 inches Sh Low Moderate X X X Description: Glossy, green foliage. Comments: Shade tolerant. *Dichondra carolinensis Dichondra 1-2 inches S, Sh Moderate Low X X X Description: Bright green foliage. Comments: Prefers moist soil. Withstands some foot traffic. Susceptible to Alternaria fungus. Dyckia brevifolia Miniature agave 6 inches S, PS High Moderate X X X Description: Glossy green leaves with white midrib on underside. Comments: Well-drained soil is essential. Dissotis rotundifolia Spanish shawl 6 inches PS, Sh Low Low X Description: Pink flowers. Comments: Demands moist conditions. Evolvulus spp. Blue daze 12 inches S Moderate High X X X

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Enviroscaping to Conserve Energy: Ground Covers for South Florida 6 Table 1. Groundcover selection for south Florida. Scientific Name Common Name = Native Height Light1 Drought Tolerance Salt Tolerance Under trees Banks & slopes Edging Seaside Open areas Description: Silvery leaves and blue flowers. Comments: Fails in wet soils. Episcia spp. Flame violet 6 inches PS, Sh Low None X Description: Leaves can be variously green, bronze or coppery, and are sometimes variegated. Flowers are red, orange or yellow throughout warm months. Comments: Many cultivars, mostly of E. cupreata are available. Demands moist, fertile soil. Temperatures below 40F will damage plant. *Ernodea littoralis Golden creeper 12-36 inches S High High X X X Description: Yellowish-green foliage. Comments: Tolerates poor conditions and neglect. Var. angusta is a pineland form with very narrow leaves. Euphorbia millii Dwarf crown of thorns 9 inches S High High X X X X Description: Red bracts surround flowers most of the year. Comments: Cultivar 'Fireball' is best. Ficus montana Oakleaf fig 6-9 inches PS, Sh High Low X Description: Bright green leaves. Comments: Interesting oak-like leaves. Coarse texture. Ficus pumila Creeping fig 12 inches S, PS High Moderate X X Description: Fine-textured green leaves. Comments: Occasional shearing is required. Plant will climb up walls and trees. Stems grow thick and woody with age. Ficus sagittata (F. radicans) Trailing fig 12 inches S, PS High Moderate X X Description: Gray-green foliage. Comments: Prefers moist, heavy soils. Better ground cover than F. pumila. Fittonia verschaffeltii Nerve plant 6 inches PS, Sh Low None X Description: Dark green leaves with red or white veins. Comments: White-veined form tends to be easier to grow. Plants are damaged below 45F. Requires moist, fertile soil.

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Enviroscaping to Conserve Energy: Ground Covers for South Florida 7 Table 1. Groundcover selection for south Florida. Scientific Name Common Name = Native Height Light1 Drought Tolerance Salt Tolerance Under trees Banks & slopes Edging Seaside Open areas Gardenia jasminoides ''Prostrate' (G. radicans) Dwarf gardenia 6 inches S, PS Moderate None X Description: Small, glossy, green leaves. White flowers in spring and summer. Comments: Prefers moist, acid soils. Glottiphyllum depressum Fig marigold 6 inches S High High X X X X Description: Yellow flowers in spring and early summer. Comments: Excellent for dry, sandy slopes. Gynura aurantiaca 'Purple Passion' Velvet plant 9 inches PS Low None X Description: Deep green leaves are purple below, covered with purple hairs, and have purple veins. Comments: Requires moist, fertile soil. Can be sheared if it becomes rangy. Hedera canariensis Algerian ivy 6 inches Sh Moderate High X X X Description: Dark green foliage. Comments: Prefers moist, shady sites. H. canariensis has larger leaves but is less aggressive than H. helix. Variegated form is available. Highly salt tolerant. Hedera helix English ivy 6 inches Sh Moderate High X X X Description: Dark green foliage. Comments: Prefers moist, shady sites. Many cultivars with varying leaf shape are available. H. helix is coarse-textured with smaller leaves than H. canariensis. Will climb up trees and walls. *Helianthus debilis Beach sunflower 12-24 inches S High High X X Description: Glossy, green leaves. Yellow flowers all year. Comments: Good sand binder for dry, coastal areas. Hemerocallis spp. Daylily 6-12 inches, 12-36 inches when in flower S, PS High High X X X Description: Light green leaves. Summer flowers in yellow, pink, and orange. Comments: Relatively pest free.

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Enviroscaping to Conserve Energy: Ground Covers for South Florida 8 Table 1. Groundcover selection for south Florida. Scientific Name Common Name = Native Height Light1 Drought Tolerance Salt Tolerance Under trees Banks & slopes Edging Seaside Open areas *Ilex vomitoria 'Schillings Dwarf' Dwarf yaupon holly 1-3 feet S High High X X X Description: Small, glossy, green leaves. Comments: Extremely compact form of this native species. Fast growing. *Ipomoea pescaprae Beach morning glory, railroad vine 4-6 inches S High High X X X Description: Light green foliage. Pink-lavender flowers in summer. Comments: Prefers sandy soils. Grows best along the seashore. *Iva imbricata Beach elder 1-3 feet S High High X Description: Small, glossy, green leaves. Comments: Excellent dune stabilizer. Spreads horizontally, rooting along stems. Juniperus chinensis Chinese juniper 1-3 feet S High Moderate X X X Description: Foliage ranges from blue-gray to green. Comments: Cultivars 'Parsonii,' 'Parsonii Varietgata,' var. procumbens 'Nana,' and var. procumbens 'Aureovariegata' are best suited as ground covers. Juniperus conferta Shore juniper 1-2 feet S, PS High High X X X X Description: Green to blue-green foliage. Comments: Fast grower. Drought and salt tolerant. Cultivars 'Compacta' and 'Blue Pacific' are particularly dwarfed. *Lantana depressa Dwarf lantana 8 inches S High Moderate X X Description: Light green leaves. Yellow flowers all year. Comments: Endemic to southern Florida pine rocklands. Lantana montevidensis Trailing lantana 18-24 inches S Low Moderate X X X X Description: Green leaves. Lavender flowers all year. Comments: Fruit is poisonous. *Lippia (Phyla) nodiflora Lippia, match weed 3 inches S, Sh High High X X X Description: Leaves are greenish to purplish. Red, purple and white flowers most of the year. Comments: Drought, wetness, and salt tolerant. Takes some foot traffic. Easily established.

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Enviroscaping to Conserve Energy: Ground Covers for South Florida 9 Table 1. Groundcover selection for south Florida. Scientific Name Common Name = Native Height Light1 Drought Tolerance Salt Tolerance Under trees Banks & slopes Edging Seaside Open areas Liriope muscari Lily turf, liriope, big blue lily turf 12 inches Sh High Moderate X X X Description: Dark green leaves. Purple flowers in spring are followed by black fruit. Comments: Resembles turf grass. Forms a dense mat and is excellent for edging. Does not tolerate heavy foot traffic. Variegated forms tolerate full sun. Liriope spicata Creeping lily turf, creeping liriope 6-18 inches Sh High Moderate X X X Description: Dark green foliage. Purple to white flowers in summer. Comments: Faster growing than L. muscari. Malpighia coccigera Miniature holly 1-3 feet PS Moderate Low X X Description: Small, holly-like, dark green leaves. Pink flowers and red fruits. Comments: Susceptable to nematodes. Use dwarf cultivars for ground cover. Plants are slow growing. Maranta leuconeura Prayer plant 6-18 inches PS, Sh Low None X Description: Light green to dark green leaves, with dark green or brown marks. Veins are gray or red in some varieties. Lower leaf surface is purple in var. erythroneura. Comments: Best in fertile, organic, moist soils. Susceptible to nematodes. Foliage will bleach in high light. Neoregelia carolinae 'Tricolor' Neoregelia 12 inches PS, Sh Moderate Moderate X Description: Leaves are green variegated with yellow. Inner half of leaves turn bright red when plant flowers. Comments: Requires well-drained soil. Keep leaf vase filled with water. After flowering, the mother plant slowly dies, but offsets grow from leaf axils. Neoregelia spectabilis Painted fingernail 12 inches S, PS, Sh Moderate Moderate X Description: Olive green leaves are gray-banded below, with tips that are spotted with maroon. Leaves turn bronze in full sun. Blue flowers. Comments: Requires well-drained soil. Keep leaf vase filled with water. After flowering, the mother plant slowly dies, but offsets grow from leaf axils. Nephrolepsis exaltata Boston fern 12-36 inches Sh Low Low X X Description: Bright green fronds. Comments: Prefers moist shade.

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Enviroscaping to Conserve Energy: Ground Covers for South Florida 10 Table 1. Groundcover selection for south Florida. Scientific Name Common Name = Native Height Light1 Drought Tolerance Salt Tolerance Under trees Banks & slopes Edging Seaside Open areas Ophiopogon japonicus Dwarf lily turf, mondo grass 6-12 inches Sh High Moderate X X X X Description: Dark, glossy, green leaves. Comments: Tolerates poor soils. Good for edging. Does not tolerate heavy foot traffic. Flowers are usually hidden by leaves. *Peperomia obtusifolia Peperomia, dwarf rubber tree 18-20 inches PS, Sh High Low X X Description: Dark green leaves. Comments: Moist, well-drained soils are best. Philodendron scandens (P. oxycardium, P. cordatum) Heart leaf philodendron 6 inches PS, Sh Moderate Low X Description: Glossy, green leaves. Comments: Fast growing. Will climb unless controlled. Prefers moist, fertile soils. Pilea microphylla Artillery plant 12 inches S, PS Moderate Low X X X Description: Light green, succulent leaves. Comments: Does not tolerate foot traffic. Grows best in moist areas, but tolerates poor conditions. Cultivar 'Stoplight' is more colorful than the typical form. Plectranthus australis Swedish ivy 12 inches PS, Sh Moderate None X Description: Bright green, waxy leaves. Purplish veins in strong light. Flowers are pale purple or white. Comments: Will burn in full sun. Fast growing. Will root along stem in moist soil. Ruellia makoyana Velvet plant 12 inches S, PS Low Low X X X Description: Dark green leaves are silver striped above and purple below. Comments: Moist, well-drained soil is best. Rumohra adiantiformis Leatherleaf fern 12-36 inches Sh Low Low X X Description: Deep green, leathery leaves. Comments: Best in moist, shady locations. Sansevieria trifasciata 'Hahnii' Snake plant 8 inches PS, Sh High Moderate X X

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Enviroscaping to Conserve Energy: Ground Covers for South Florida 11 Table 1. Groundcover selection for south Florida. Scientific Name Common Name = Native Height Light1 Drought Tolerance Salt Tolerance Under trees Banks & slopes Edging Seaside Open areas Description: Variegated dark and light green leaves. Comments: Very drought and shade tolerant. Scindapsus pictus 'Argyraeus' Silver pothos 6 inches Sh Moderate Low X Description: Dark green leaves variegated silver. Comments: Will climb unless controlled. Requires well-drained soil. Selaginella involvens Erect selaginella 12 inches Sh Low Low X X X Description: Light green, fernlike foliage. Comments: Requires moist soil. Selaginella uncinata Blue selaginella 8 inches PS, Sh Low None X Description: Pale blue-green, fernlike foliage. Comments: Vigorous in moist sites. Setcreasea pallida 'Purple Heart' Purple heart 14 inches S, PS High Moderate X X X Description: Purple foliage. Pink flowers in the summer. Comments: Performs well under trees. Prune for more compact growth. Spathiphyllum 'Clevelandii' Peace lily 3 feet Sh Low None X Description: Glossy, dark green leaves. White flowers. Comments: Requires moist, organic soil. Other dwarf cultivars are available. Stapelia nobilis Carrion flower 8 inches PS High Moderate X Description: Green stems that turn bronze in full sun. Flowers are a lurid purple, barred with brown. Comments: Drought-tolerant succulent. Odor of flowers may be objectionable. Requires well-drained soils. A number of other species have a similar growth habit. Syngonium podophyllum Nephthytis 12 inches Sh Moderate None X Description: Green leaves are often variegated. Comments: Rapid growing. Will climb unless controlled. Trachelospermum asiaticum Small leaf confederate jasmine 8-12 inches S, Sh Moderate Moderate X X X

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Enviroscaping to Conserve Energy: Ground Covers for South Florida 12 Table 1. Groundcover selection for south Florida. Scientific Name Common Name = Native Height Light1 Drought Tolerance Salt Tolerance Under trees Banks & slopes Edging Seaside Open areas Description: Glossy, dark green foliage. Comments: Forms thick mat that suppresses weeds. Trachelospermum jasminoides Confederate jasmine, star jasmine 8-12 inches S, Sh Moderate Moderate X X Description: Dark green foliage with new growth contrasting light green. Highly fragrant white flowers in midto late spring. Comments: Performs best as a vine due to long, twining stems. Resists trampling. Tulbaghia violacea Society garlic 30 inches S Moderate Moderate X X Description: Lilac-colored flowers in the spring. Comments: Does not flower well in shade. Alternating periods of wet and dry weather induce frequent flowering. *Uniola paniculata Sea oats 3-6 feet S High High X Description: Pale green foliage with attractive seed heads. Comments: Excellent sand-dune stabilizer. *Zamia pumia (Z. floridana) Coontie, Florida arrowroot 12-36 inches S, Sh High High X X X X Description: Glossy, dark green, fernlike foliage. Comments: Will not tolerate shearing or mowing. Zebrina pendula Wandering Jew 4-10 inches Sh Moderate Low X Description: Leaves are striped purple, silver and green. Comments: Prefers well-drained, moist soil. Excellent under trees. Does not tolerate foot traffic. 1Light: S = full sun, PS = partial shade, Sh = shade