Saturday, January 24, 2003

Submitted by Calvin Finch, Ph.D., Manager, Conservation Division, Water Resources & Conservation Department, SAWS, and Horticulturist

            We finally had a hard freeze in January. It means that we will probably not be harvesting any more tomatoes or roses this winter. I will miss the roses, but I am tired of the tomatoes. Most of my friends will also be glad that the tomato plants are dead. They were all polite about accepting the excess fruit, but the enthusiasm ended about Christmas time.

            Along with tomatoes and peppers, impatiens, begonias, firespike, and firebush finally froze back.

Pansies, cyclamen, snapdragons, broccoli, onions, sweet peas, carrots, stocks, spinach, and rutabagas all made it through as we would expect. Beets and lettuce also survived. Do not forget to fertilize actively growing cool weather plants every month.

On most sites the root hardy woody ornamentals (esperanza, poinciana) lost their leaves, but the stems are not frozen. We may get more cold weather that will kill them to the ground but, for now, the stems are alive and you can expect them to resprout in March or April. Even the stems of bougainvillea, oriental hibiscus, mandevillea, and plumeria are probably still alive. There is still time to get them inside shelter. If we get another freeze, one cold enough to kill the stems, you can expect to lose a good portion of the plants.

            Most salvias, lantana, plumbago, and rock rose were not killed to the ground. They, like the esperanza and poinciana, will sprout from the stems, but it is not as desirable. All of them have a tendency to get woody and untidy if they do not resprout from the roots. Leave them in place for a while longer to provide cover and feeding area for songbirds. In mid February, they can be cut back to the ground.

Most St. Augustine, Bermuda, zoysia, and buffalo grass lawns had already gone dormant, but there were a few lawns still green and growing. All of them now will be brown until mid April. Keep the winter weeds under control by mowing every two or three weeks. Do not waste water or fertilizer now. The only plants that would benefit are the winter weeds. Fertilize on or about May 1.

            Other pruning jobs in the landscape can be completed now. Open up the middle of fruit trees to encourage air movement and light penetration.  To reduce height use thinning cuts as opposed to a hedging cut. Hedging cuts cut a branch in half and leave a stub. Thinning cuts occur at the branch’s origin from another branch. Thinning cuts are better for the tree.

            The only pruning that requires pruning paint is on oak trees. Paint the wound as quickly as possible after the cut is made to help prevent oak wilt.

            Pruning on trees and shrubs should be done sparingly. Remove branches that are endangering your roof or encroaching on your sidewalks and doors.

            To get a large shrub back under control and to encourage foliage at the base, remove the oldest branches at ground level and then use thinning cuts to reduce the height of the five to eight remaining stems.

            Modern hybrid tea roses are pruned a lot like fruit tees: open the middles, remove broken or diseased branches, and reduce the height. Wait until after Valentines Day to complete rose pruning. You can remove canes from climbing roses that block pathways at any time they become a nuisance, but the main pruning should be done after the spring bloom period. That rule also applies to other spring blooming plants like Texas mountain laurel.

            Old-fashioned roses do not need pruning every year. Conifers are pruned later in the spring. Upright species can be sheared or hedged to shape them. It works best to cut a portion of the new growth in shaping. Again, use thinning cuts for size control.

            For more information on pruning, including diagrams, visit the website plantanswers.com.