Southwest Florida climates include USDA hardiness zones 9 and 10, presenting gardeners with opportunities ranging from magnolias and Spanish moss to tropical palm trees and bromeliads. Challenges abound, from the salt water and storms of the Gulf of Mexico to heavy humidity, heavy winds and serious statewide concerns about water conservation. Near-tropical conditions further encourage rapid growth of invasives, and potentials for water pollution constitute substantial threats to fragile ecosystems.
Geography and Climate
Southwest Florida occupies a peninsula between the Gulf of Mexico and the Atlantic Ocean. In places, the distance between the two bodies of water is under 200 miles. Much land is very close to sea level; salt and sand content are high even in arable land. Plant-finding indices list heat-, salt- and drought-tolerance among plant qualities for both native and other plants. Plant information sites reflect strong cooperation among state and federal agencies and nonprofit organizations concerned with the environment.
The Right Plant in the Right Place
Plants that do well in southwest Florida can tolerate semi-tropical humidity but do not need heavy watering. Plants like annual flowers or small perennials that do not tolerate sandy or salty soil may do best in pots with regular potting soil. This allows you to plant a wider variety of flowers than in the ground and allows you to make the most of limited fresh water. The University of Florida Extension further suggests planting annuals for fall and winter bloom, taking advantage of cooler night temperatures and more naturally available water from storms.
Special Plants for Special Places
Southwest Florida residents are encouraged to use the principles of xeriscaping wherever possible. Scotch pines, varieties of juniper and brooms vary the textures and shapes of native grasses. Poinciana, American hornbeam and Chinese fringe tree all function well in southwest Florida--along with several varieties of palms. Several varieties of viburnum and native azalea flourish in zones 9 and 10, as do several members of the jasmine family. Lantana and geranium, regarded as annuals in the north, become perennials. Lantana grows with such enthusiasm that it has gone from being a decorative annual to an invasive nuisance in some areas.
The EPA, the State of Florida Dept. of Environmental Protection, neighboring states and Florida water management agencies work to mitigate damage to Florida wetlands. Flora and fauna lists, plus publications to guide groups through wetland conservation and restoration can be found at the Florida Dept. of Environmental Protection website. Guidance is provided for plantings to support freshwater, saltwater and estuarial wetlands.
Given the delicate balance Floridians must maintain with their fragile and unique ecosystems, invasive plants are of major concern. Semi-tropical conditions and infrequent frost foster rapid growth (an Australian pine can grow 5 to 10 feet per year and the suffocating mats created by Japanese climbing fern can blanket a tree with 4-foot-thick layers of vines). Poisonous plants (Brazilian pepper behaves like poison ivy, and tallow-tree sap is poisonous to animals and humans) threaten settled and wild areas. Tampa Bay invasives include a list of 20 plants so aggressive that kudzu does not even make the list, and the list notes that cogon grass is one of the world's 10 worst weeds. The Bureau of Invasive Weed Management provides a long list of assisting agencies and very clear directions for homeowners to remove invasives while doing as little damage to the environment as possible. Whether improving, protecting or planting a new area, Florida state and county agencies offer plenty of cautions, but also a wealth of support to gardeners.