If your neighbor's garden burgeons while yours languishes, it might be the kind of plants you're trying to grow. Plants that thrive in Louisiana landscapes need to be able to take the heat and humidity common to the state, which ranges from U.S. Department of Agriculture plant hardiness zones 8a to 10a. Facing temperatures between a low of 10 degrees Fahrenheit to an average high of 93 F and high humidity, Louisiana plants need to be tough customers.
Annuals That Laugh at Heat and Humidity
Louisiana State University lists about two dozen warm-season annuals that do well during Louisiana summers. They include marigolds (Tagetes spp.), coleus (Solenostemon scutellarioides) and zinnias (Zinnia spp.). For spring and fall planting, several plants that are annuals in most parts of the country survive winters in Louisiana. Pansies (Viola x wittrockiana), hardy in USDA zones 6 through 10, rule, but other favorites include sweet William (Dianthus spp.), USDA zones 3 through 9, and snapdragons (Antirrhinum spp.), USDA zones 7 through 10. A university program called Louisiana Super Plants, started in 2010, tests and recommends specific cultivars in all plant categories that perform well in Louisiana landscapes.
Perennials With Persistence
Hardy salvias (Salvia spp.), USDA zones 4 through 10; black-eyed Susans (Rudbeckia spp.), USDA zones 3 through 9; and daylilies (Hemerocallis spp.), USDA zones 3 through 9, are three perennials commonly seen in Louisiana gardens. Several plants grown elsewhere in the country as perennials, however, are treated as cool-season (October through February) annuals in Louisiana. They include delphiniums (Delphinium spp.), USDA zones 3 through 7, and foxgloves (Digitalis spp.), USDA zones 4 through 8.
Some Shrubs That Like It Hot
Azaleas (Rhododendron spp.), USDA zones 5 through 8, are among the most common Louisiana landscape plants, along with camellias. Louisiana gardeners plant both the spring-blooming Camellia japonica and the fall-blooming Camellia sasanqua, both hardy in USDA zones 7 through 9. Delightfully fragrant gardenias (Gardenia jasminoides), USDA zones 8 through 11, are ubiquitous in Louisiana, providing pure white blooms, shiny, evergreen foliage and heady scent.
Try These Reliable Trees
Trees can be tricky in climates where night temperatures often don't cool below 75 degrees, because many woody plants need a cool-weather dormancy period. Trees common to Louisiana landscapes include dogwoods (Cornus spp.), USDA zones 5 through 9; crape myrtles (Lagerstromia spp.), USDA 6 through 9, a Southern-state staple much envied by those in colder climates; and Southern magnolias (Magnolia grandiflora), USDA zones 7 through 9, with huge blooms and leathery, evergreen leaves.
- Louisiana State University Agricultural and Extension Center: A Guide to Louisiana-Friendly Landscaping
- United States Department of Agriculture: Plant Hardiness Zone Map
- Netstate: Louisiana Almanac
- Louisiana State University Agricultural and Extension Center: About Louisiana Super Plants
- Louisiana State University Agricultural and Extension Center: “Diamonds Blue” Delphinium -- Cool-Season Bedding Plant
- Louisiana State University Agricultural and Extension Center: Camelot Series Foxglove -- Louisiana Super Plant Fall 2010
- U.S. National Arboretum: Camellias: Expanding Their Territory
- The Times-Picayune: Choose Landscape Plants That Are Comfortable in the Heat