A few years ago I planted a royal poinciana tree in the front lawn. While the tree is beautiful and large now, the grass does not grow anymore under it. Is there a grass that will grow in the South Florida heat in such a highly shaded area?
St. Augustinegrass is the most shade tolerant of the warm season grass species and the dwarf varieties of St. Augustinegrass varieties tolerate shade best. Cultivars (cultivated varieties) that have good shade tolerance include Bitterblue, Seville, Jade and Palmetto. Check with local sod growers to see what is available in South Florida.
Shade tolerant does not mean shade proof, it means the species will grow better in shade but still needs sunlight. The amount of sunlight required to grow a decent turf is going to be between 4 and 6 hours of sunlight per day. Therefore, it is very important to prune your tree to allow light to filter down to the grass.
Another option to consider is planting a shade-loving ground cover under your tree. Asiatic jasmine, also called “Dwarf Confederate jasmine” or “small leaf Confederate jasmine” is a common South Florida ground cover. Another good ground cover for shady spots is Bugleweed (Ajuga reptans). Visit a local garden center to see what else is available.