Roses (Rosa spp.) must be pruned regularly to be at their best. Some only need a light pruning, but others need to be cut back significantly once a year along with occasional tidying up throughout the year. The best time to cut them back in Texas and how hard they need to be cut back depends, to a certain extent, on the rose -- but the greater determining factor is where the roses are in Texas.
Roses for Texas
Roses are generally hardy in U.S. Department of Agriculture plant hardiness zones 2 to 11, depending on the species and cultivar.
'Fragrant Cloud' (Rosa 'Tanellis' or Rosa 'Fragrant Cloud') is a hybrid tea rose that has good resistance to rust and powdery mildew. It blooms repeatedly in spring and summer, producing 5-inch diameter orange-red flowers. 'Queen Elizabeth' (Rosa 'Queen Elizabeth') is a grandiflora rose that blooms from spring to first frost, producing pink, 2- to 4-inch wide flowers. Both of these roses do well in Texas and are hardy in USDA zones 5 to 9.
'Flower Carpet® Scarlet' (Rosa 'Flower Carpet® Scarlet,' USDA zones 4 to 11) is a groundcover-type rose that blooms in red from spring through fall. This rose is tolerant of high humidity and heat and has good disease resistance.
When to Prune
The best time to prune most roses is one month before the last expected hard frost in the spring. In Amarillo the last hard frost is usually around April 18. In Dallas it commonly occurs around March 3. Houston's last frost is usually February 8, while San Antonio gets the last frost around February 28. When roses are pruned earlier, they grow new stems and leaves at their bases and a cold snap is likely to cause serious damage or even kill the bush.
Climbers are the only roses that should be pruned right after they finish blooming.
Tidy up all types of roses at any time throughout the year by removing spent blossoms and dead and diseased stems as soon as they are noticed.
Pruning in Hot Climates
Roses should be cut back more drastically in USDA zones 8 to 10 in central and south Texas because the growing season is much longer there.
Large roses like hybrid teas, floribundas and grandifloras can be cut down to a height of 1 to 2 feet. This drastic pruning will result in larger flowers. If height is not a problem and such drastic pruning is not desired, they should be cut back by one-third their height.
Smaller roses like shrub roses, which includes 'Knock Out®' roses (Rosa 'Knock Out®,' USDA zones 5b to 9), should be cut back to 2 feet shorter than their desired height, but not by more than half their height.
Groundcover roses like 'Flower Carpet® Scarlet' can be cut back by about one-third their height.
If the roses did not shed their leaves in the winter, strip them all off. This makes way for new, fresh foliage for the coming year.
Pruning in Cooler Climates
Roses in the colder USDA zones 6 and 7 of north Texas will not need to have as much stem removed.
Larger roses can be cut down to a height of 1 to 2 feet, or one-third their height, whichever is preferred. They usually produce larger flowers when they are cut back to 1 to 2 feet tall.
Shrub roses and groundcover roses are cut back in cooler zones just like they are in the warmer climates of central and south Texas.
The leaves usually do not need to be removed in these colder areas. They are generally long gone by pruning time.
Always use sharp bypass pruners and make pruning cuts about ¼ inch above a growth bud. Disinfect the pruners with household disinfectant, rinse them and dry them off before using them. Also, when pruning diseased branches, the pruners should be disinfected between cuts to prevent the spread of disease. Wear heavy gardening gloves with reinforced palms and long sleeves for protection against thorns. Seal stems larger than a pencil with white household glue. Clean up all of the leaves, pieces of stem and other debris and put them in the trash. When left around the base of the roses, they will provide a growing environment for bacterial and fungal diseases.