We left January with a 78-degree high one day and welcomed February with a 17-degree low the next. These dramatic swings in temperature are often painful for Austinites, for whom prolonged bitter cold is an anomaly. And it can wreak havoc on our gardens. Our plants don’t know if they are supposed to be dead, dormant or budding out.
As gardeners, we certainly want to take advantage of those sporadic and delightfully warm days to get caught up with our landscaping chores. But it’s still just a bit early.
There are still a few more weeks left with a danger of frost. According to the USDA Hardiness Zone map for the Austin area, our average last frost comes between March 1 and March 31. It’s typically the middle of March. (As we all know, using the term “typical” can get you into some gardening trouble here with our yo-yo like weather patterns.)
Try to be patient. (I know it’s hard when the sun is shining and everything is dead, brown and ugly.) Waiting to prune until after the last freeze prevents stimulation of new, tender growth that can be damaged by frost and can stress the plant by bringing it in and out of dormancy.
Getting started – pruners, loppers and shears
Good tools can make a big difference – for you and for your plants. A clean cut is much better for plants than ragged or torn edges. Sharp, high-quality tools like Felco or Fiskars brands make cutting easier for the gardener, too. Use hand pruners for smaller plants and some woody perennials up to 1 inch in diameter. For larger woody perennials and shrub limbs, longer-handled loppers help provide more leverage when cutting. Shears work best for shaping smaller shrub branches or grasses.
First, assess the damage on your dormant perennials — plants like Lantana, Esperanza, or Salvia. If you scrape the stem of most of these perennials you will be able to tell whether it is alive and dormant, or whether it has succumbed to winter. Look for signs of green close to the base of the plant. Normal pruning of most of our perennials will suffice if the plant is just dormant. These woody perennials are typically very hardy. While it might take them a little longer to bud out after a cold winter like this, most do, unless they were newly-planted before winter or are particularly small and not well established. Make clean sharp cuts leaving about 6” of stem above ground. New growth from these plants will come from the base, so cutting them low will not affect their development.
Many aloes and agaves were severely damaged by our hard freezes this winter. Freeze-damaged succulents usually turn a lighter color, almost white, soon after the freeze. Later, the damaged part of the plant will wilt, and then turn black with rot. In some succulents, the affected parts eventually fall off.
If the center bud remains green and firm, the plant will likely to grow and recover, in spite of dead leaves. However, dead and damaged parts will never recover, and you can remove them. You should also look for new growth underneath the dead leaves and down in the base of the plant. These pups can often survive under the cover of the dead leaves.
If the center of the tree is fine, it will probably survive. Cut off dead or highly damaged leaves. Palms grow primarily in the warm spring and through the summer, and may look much better by the end of the summer.
Cycads – Sago Palms
Sago palms are popular in Austin, and many gardeners have them in their landscapes. Not actually palms at all, Sagos are cycads and they are normally hardy to 26 degrees. However, prolonged hard freezes cause damaged leaves to turn yellow or brown. These should be pruned to encourage new growth. You can remove all the leaves – they will grow back. If the trunk and leaf crown are still firm, the plant will likely recover. Don’t worry if it looks like a bad haircut for a while – all the leaves will eventually regrow from the trunk.
Some people start pruning Crape Myrtles earlier, but just like other plants, they are still susceptible to late season frosts and should not be pruned until after that danger has passed. In spite of industry-wide efforts to educate homeowners and maintenance crews about the dangers of “Crape murder,” you can still spot Crape Myrtles all over town that have been topped off — cutting back all the major limbs severely and straight across. It’s almost as though they’ve been put in a guillotine — and about as attractive.
It’s an odd practice, considering that no other trees like live oaks, elms, yaupon hollies or mountain laurels, are treated that way when they are pruned.
Crape Myrtles should never be topped. Removing the terminal growing section of a tree ruins the natural shape and appearance, stunts its growth and weakens it. It can also reduce the number of blooms that the tree produces in the summer. When pruned back too far, new branches may not be able to support the weight of summer’s blooms, particularly when wet. Crape Myrtles should be pruned for shape and style, removing any twigs or branches smaller than the diameter of a pencil. To prune larger branches, trace down from the seedpod to where the stem meets a branch, and cut approximately 6 inches above that intersection. This ensures that the new branch will be strong enough to support future growth below your cut.
Once you’ve finished pruning and everything starts to bud out, don’t be tempted to fertilize newly pruned plants. They need to use all of their energy to begin new growth. Fertilizing now will over-stress them. Wait until later in the spring — at least a month — when they are established again.