Lantanas produce clusters of brightly colored flowers on stalks that emerge above the bright green foliage. Lantanas grow as a perennial in areas that experience mild frost or as an annual in colder regions. Deadheading and trimming back the plants throughout the growing season encourages the plants to produce more blossoms by preventing seed formation. Seed set takes energy and nutrients away from the plant so it doesn't set new buds; removing the old flowers encourages the plant to form more buds in an effort to produce viable seed.
Inspect the lantana plant as the flowers begin wilting. Varieties that develop a swollen seedpod at the base of the declining flower require deadheading. Those with no swollen seedpod are self-cleaning and deadheading is not necessary to prolong flower bloom.
Snip the old flower cluster off the plant after most of the petals have withered. Cut the flower stem within a quarter-inch of the topmost set of leaves.
Prune the entire plant if most of the flower clusters have faded and further blooms or buds aren't forming. Trim back the plant by up to one-fourth its height to encourage a fresh flush of buds and flowers.
Cut back the old dead stems in spring before new growth begins. Trim back the old stems to within 4 inches of the ground to encourage lush new growth and flower bud formation.