Planting Nursery Plants -- Continue to plant warm-season annual flowers and vegetables (tomatoes, peppers, marigolds, petunias, and the like) as long as you have enough time for them to beat the summer heat. (However, in hot desert areas, for example, that means no later than late February.) If in doubt, give a quick call to the garden center nearest you.
Deadheading 101 -- Deadhead fading flower blossoms. You'll keep your garden neater and flowering better longer.
Mulch Matters -- If you haven't already, apply a layer of mulch on flower beds and around trees and shrubs 2-3 inches around the base of plants. It reduces weeds, conserves moisture, and prevents disease. Great stuff!