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EES38 Enviroscaping to Conserve Energy: Ground Covers for Central Florida1 A.W. Meerow and R.J. Black2 1. This document is Circular EES-38, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Publication date: July 1993. Reviewed and 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, 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 (IFAS) is an Equal Employment Opportunity Affirmative Action Employer authorized to provide research, educational information and other services only to individuals and institutions that function without regard to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. 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 / Larry R. Arrington, Interim 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 air temperature. Called evaporative cooling, this interaction can lower air temperatures 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 lawns. 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 same sized landscape 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
Enviroscaping to Conserve Energy: Ground Covers for Central 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. Augustinegrass lawns. At the lowest fertilizer level, centipedegrass lawns need 87 pounds of nitrogen per acre per year (2.9 million Btu). Choosing centipedegrass instead of St. Augustinegrass 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 that 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 other 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 salt and drought tolerant. 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 turfgrass. 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 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 Central Florida encompasses an area of great climatic diversity. Killing frosts regularly occur in the northern portion of central Florida, but are rare in the southern part. Consequently, some of the ground covers in Table 1 will not survive winter temperatures in the north central Florida. Frost sensitivity is indicated in the Comments section of the table where appropriate; frost-sensitive species are best suited to the southern portion of central Florida. Additional selections for south central Florida are in the companion publication EES-39, "Enviroscaping to Conserve Energy: Ground Covers for South Florida." The table also will help home gardeners and landscape professionals select ground covers appropriate for central Florida site conditions. For each species, the table lists the expected height of the mature plant, along with the color of both leaves and flowers. Relative salt and drought tolerance is indicated as well. 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.
Enviroscaping to Conserve Energy: Ground Covers for Central Florida 3 Turfgrass 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 inputs required by a lawn. References Parker, J.H. 1982. An Energy and Ecological Analysis of Alternate Residential Landscapes. J. Environ. Syst. 11: 271-288. Whiffen, H.J.H. 1993. E2 & E Energy Efficiency & Environmental news. UF/IFAS Energy Extension Service, Feb., Gainesville, FL.
Enviroscaping to Conserve Energy: Ground Covers for Central Florida 4 Table 1. Selection of groundcovers for central Florida. Scientific Name Common Name = Native Height Light1 Drought Tol.2 Salt Tol.2 Under trees Banks & slopes Edging Seaside Open areas Ajuga reptans Bugle weed, carpet bugle 2 inches; 12 inches in flower S,PS L L X X X Description: Dark green foliage, purple flowers in early summer. Comments: Nematode sensitivity; bronze-leaved form 'Rubra' commonly grown in Florida. Aloe spp. Aloe 12 inches S,PS H H X X X Description: Succulent, often bi-colored leaves; red, orange or yellow flowers in summer. Comments: A number of low-growing species available; drought tolerant. Aspidistra elatior Cast iron plant 20 30 inches Sh L M X Description: Green foliage; variegated form available. Comments: Slow growing. Carpobrotus edulis Hottentot fig, iceplant 6 inches S H H X X Description: Grayish-green leaves, yellow to rose-purple flowers in summer. Comments: Excellent seaside ground cover and sand binder. *Licania michauxii Gopher apple 3 12 inches S H H X X Description: Leaves dark green above, downy white below; red fruit in summer. Comments: Tolerates drought and poor soils. Cuphea hyssopifolia Cuphea, false heather 12 15 inches S,PS L N 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 M L X X Description: Leaves are different shades of green to red, often striped. Comments: Prefers shady, moist locations; sensitive to frost. Cyrtomium falcatum Holly fern 24 inches Sh L M X X X Description: Glossy, green foliage. Comments: Shade-tolerant.
Enviroscaping to Conserve Energy: Ground Covers for Central Florida 5 Table 1. Selection of groundcovers for central Florida. Scientific Name Common Name = Native Height Light1 Drought Tol.2 Salt Tol.2 Under trees Banks & slopes Edging Seaside Open areas *Dichondra carolinensis Dichondra 1 2 inches S,Sh L L 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 H M X X X Description: Glossy, green leaves with white midrib on underside. Comments: Well-drained soil is essential. *Ernodea littoralis Golden creeper 12 36 inches S H H X X X Description: Yellowish-green foliage. Comments: Extremely drought-tolerant; tolerates poor conditions and neglect. Var. angusta is a pineland form with very narrow leaves. Ficus pumila Creeping fig 12 inches S,PS H M-H X X Description: Fine-textured green leaves Comments: Occasional shearing required; will climb up walls and trees; stems grow thick and woody with age. Ficus sagittata (F. radicans) Trailing fig 12 inches S,PS M M-H X X Description: Gray-green foliage. Comments: Prefers moist, heavy soils; better ground cover than F. pumila. Gardenia jasminoides 'Prostrata' (G. radicans) Dwarf gardenia 6 inches S,PS M N X Description: Small, glossy, green leaves; white flowers spring and summer. Comments: Moist, acid soils. *Gelsemium sempervirens Carolina jessamine, Carolina yellow jasmine 6 inches S,PS H L X X X Description: Yellow flowers in early spring. Comments: All parts poisonous; slow-growing; prefers moist soil. Glottiphyllum depressum Fig marigold 6 inches S H H X X X X Description: Yellow flowers in spring and early summer. Comments: Excellent for dry, sandy slopes.
Enviroscaping to Conserve Energy: Ground Covers for Central Florida 6 Table 1. Selection of groundcovers for central Florida. Scientific Name Common Name = Native Height Light1 Drought Tol.2 Salt Tol.2 Under trees Banks & slopes Edging Seaside Open areas Hedera canariensis Algerian ivy 6 inches Sh M H X X X Description: Dark green foliage. Comments: Prefers moist shade; larger leaves but less aggressive than H. helix; variegated form available. Hedera helix English ivy 6 inches Sh M H X X X Description: Dark green foliage. Comments: Prefers moist shade; many cultivars with varying leaf shape; coarse-textured (finer than H. canariensis); will climb up trees and walls. *Helianthus debilis Beach sunflower 12 24 inches S H H X X Description: Glossy, green leaves, yellow flowers all year. Comments: Good sand binder in dry, coastal areas. Hemerocallis spp. Daylily 6 12 inches; 12 36 inches in flower S,PS H H X X X Description: Light green leaves; summer flowers in yellow, pink, orange. Comments: Relatively pest free; drought tolerant. *Ilex vomitoria 'Schellings Dwarf' Dwarf yaupon holly 12 36 inches S H H X X X Description: Small, glossy green leaves. Comments: Extremely compact form of native species; fast growing. *Ipomoea pescaprae Beach morning glory, railroad vine 4 6 inches S H H X X X Description: Light green foliage; pink-lavender flowers in summer. Comments: Sandy soils; best along seashore. *Iva imbricata Beach elder 12 36 inches S H H X Description: Small, glossy green leaves. Comments: Excellent dune stabilizer; spreads horizontally, rooting along stems. Juniperus chinensis Chinese juniper 12 36 inches S H L-M X X X Description: Foliage blue-gray to green. Comments: Cultivars 'Parsonii,' 'Parsonii Variegata,' var. procumbens 'Nana,' and var. procumbens 'Aureovariegata' best suited as ground covers.
Enviroscaping to Conserve Energy: Ground Covers for Central Florida 7 Table 1. Selection of groundcovers for central Florida. Scientific Name Common Name = Native Height Light1 Drought Tol.2 Salt Tol.2 Under trees Banks & slopes Edging Seaside Open areas Juniperus conferta Shore juniper 12 24 inches S,PS H H X X X X Description: Green to blue-green foliage. Comments: Fast grower; drought tolerant; most salt-tolerant juniper; cultivars 'Compacta' and 'Blue Pacific' are particularly dwarfed. *Lantana depressa Dwarf lantana 8 inches S H M X X Description: Light green leaves, yellow flowers all year. Comments: Drought tolerant. Lantana montevidensis Trailing lantana 18 24 inches S L M-H 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 H H X X X Description: Leaves greenish to purplish; red, purple and white flowers most of the year. Comments: Drought and wet tolerant; takes some foot traffic; easily established. Liriope muscari Lily turf, liriope, big blue lily turf 12 inches Sh H M X X X Description: Dark green leaves; purple flowers in spring followed by black fruit. Comments: Resembles turfgrass; forms dense mat; excellent edging; drought tolerant; no heavy foot traffic. Variegated forms tolerate full sun. Liriope spicata Creeping lily turf, creeping liriope 6 18 inches Sh H M-H X X X Description: Dark green foliage; purple to white flowers in summer. Comments: Drought tolerant; faster growing than L. muscari. *Mitchella repens Partridge berry, twin berry 1 2 inches Sh L L X X X Description: Dark, glossy green foliage; red fruits. Comments: Best in shade with moist, acid soils; takes some foot traffic. Nephrolepsis exaltata Boston fern 12 36 inches Sh L L X X Description: Bright green fronds. Comments: Prefers moist shade.
Enviroscaping to Conserve Energy: Ground Covers for Central Florida 8 Table 1. Selection of groundcovers for central Florida. Scientific Name Common Name = Native Height Light1 Drought Tol.2 Salt Tol.2 Under trees Banks & slopes Edging Seaside Open areas Ophiopogon japonicus Dwarf lily turf, mondo grass 6 12 inches Sh H M-H X X X X Description: Dark, glossy, green leaves. Comments: Drought resistant; tolerates poor soils; good edging; no heavy foot traffic; flowers usually hidden by leaves. Rumonra adiantiformis Leatherleaf fern 12 36 inches Sh L L X X Description: Deep green, leathery leaves. Comments: Frost-sensitive; best in moist, shady locations. Selaginella involvens Erect selaginella 12 inches Sh L L X X X Description: Light green, ferny foliage. Comments: Moist soils. Selaginella uncinata Blue selaginella 8 inches PS, Sh L N X Description: Pale blue-green, fernlike foliage. Comments: Vigorous in moist sites. Setcreasea pallida 'Purple Heart' Purple heart 14 inches S,PS H H X X X Description: Purple foliage, pink flowers in summer. Comments: Hardy to 25F; performs well under trees; prune for more compact growth. Trachelospermum asiaticum Small-leaf Confederate jasmine 8 12 inches S,Sh M M X X X Description: Dark, glossy, green foliage. Comments: Forms thick mat that suppresses weeds. Trachelospermum jasminoides Confederate jasmine, star jasmine 8 12 inches S,Sh M M X X Description: Dark green foliage, new growth contrasting light green; highly fragrant white flowers in mid to late spring. Comments: Performs best as a vine due to long, twining stems; resists trampling. Tulbaghia violacea Society garlic 30 inches S M M X X Description: Lilac-colored flowers in spring. Comments: Does not flower well in shade; wet-dry periods induce frequent flowering.
Enviroscaping to Conserve Energy: Ground Covers for Central Florida 9 Table 1. Selection of groundcovers for central Florida. Scientific Name Common Name = Native Height Light1 Drought Tol.2 Salt Tol.2 Under trees Banks & slopes Edging Seaside Open areas *Uniola paniculata Sea oats 36 72 inches S H H X Description: Pale green foliage, attractive seed heads. Comments: Excellent sand-dune stabilizer. *Zamia pumila (Z. floridana) Coontie, Florida arrowroot 12 36 inches S,Sh H H X X X X Description: Glossy, dark green, fernlike foliage. Comments: Drought resistant; no shearing or mowing. Zebrina pendula Wandering Jew 4 10 inches Sh L L X Description: Leaves striped purple, silver and green. Comments: Prefers well-drained, moist soil; excellent under trees; no traffic. 1Light requirements: S = full sun, Sh = shade, PS = partial shade 2Drought and salt tolerance: L = low, M = moderate, H = high