Once plants have flowered and produced seed the plants puts all of its energy into maturing the seed and does not bloom again.
Blooms may last longer in cooler climates but cooler climates do not have the potential for two spectacular bloom periods each year as South Texas does. Most of us expect our flowering perennials to bloom well in the spring but overlook the best possible season for bloom – – fall. Plants are not flowering to make us happy; they are flowering to produce seed and complete the reproductive stage of their life cycle. If the old flower stalks are cut off and not allowed to mature seeds, the plant will attempt to make more seed. Then we get to enjoy another bloom cycle. Flower petals burn in the summer sun. August is the time to act. Remember, shrubs that bloom after June usually do so from buds that are formed on shoots that grow the same year. These shrubs should be pruned in late winter to promote vigorous shoot-growth in spring.
Hot weather greatly shortens the life and beauty of blooms. During the spring bloom season, Texas weather is making the transition from winter to summer. Unfortunately the transition period may only be for several days, i.e., Texas temperatures rapidly change from frosty to scorchy. The fall weather conditions, in comparison, are ideal for blooms. Usually extremely hot weather ends in September and the cooler temperatures, especially at night, signal that the South Central Texas second “spring” has begun. These cooler temperatures stimulate plant growth and intensify the color and duration of the blooms. Many people do not prepare their plants for this second spring so they miss really the most spectacular bloom period.