Answers to common questions from North Texas gardeners as we head into winter
It’s a curious collection of questions that come to the surface late in the gardening season. These are some of the most common ones that I’m asked as late fall heads into the winter.
“What trees are the best sources of fall color here in North Texas?”
I always begin my answer to that question with a tip: Fall color is a fleeting thing. It only lasts for five to seven days. Don’t invest in a poor type of tree (Bradford pear) just because it’s beautiful for a few days one time per year. I want a tree that gets an “A” grade every week of the year. At the top of that list, I’d put Shumard red oak (colorful many years in the fall) and Chinese pistachios (colorful almost every year). Sweet gums are good annually in acidic soils (primarily East Texas). And one of my personal favorites in our own landscape is ginkgo. It turns buttery yellow each fall, plus I love its unusual leaves and winter branch pattern. However, it is slow to gain height. Be sure you have a male (fruitless), grafted variety. You don’t want the putrid-smelling fruit.
“What are the yellow circles that are showing up in my St. Augustine these past couple of weeks?”
That’s almost assuredly brown patch, now being called “large patch” by university turf and pathology experts. The yellow patches are 18 to 30 inches in diameter, and infected leaf blades pull loose easily from the runners. You’ll be able to see the active decay at the bases of their blades to confirm its presence. Apply a labeled turf fungicide such as Azoxystrobin at first signs of an outbreak. It typically shows up with the first cool, wet weather of fall. Affected grass will be weakened but not killed, so don’t panic.
“Are there any kinds of tree leaves I should not put into my compost pile? I’ve heard that oak and pecan leaves have an oil that hurts other plants.”
I can answer from personal experience. We live in a pecan and oak forest with perhaps 250 trees around us. I gather all the leaves from two acres’ worth of those trees, and I compost them for a couple of years before I work them into my beds. By then they’re fully broken down into soft humus. I have never had any damage to any of my plants, even including more “delicate” types. Those tannic oils and acids will have leached away long before you’ll use the organic matter. Compost away!
“I’ve had cold damage done to my landscape the past two winters. What can I do to protect my new plants this winter?”
Keep them properly hydrated through the winter. That’s especially important as cold spells approach – water deeply. Do not prune plants that are likely to be hurt too early in the dormant season. Pruning stimulates new growth, and you don’t want it to come out too soon. Perhaps most important, where you can, cover vulnerable plants with frost cloth. Even though it’s lightweight, it carries a big punch against freeze damage. Pull it taut over the tops of the shrubs and down to the ground. Weight it firmly in place with bricks or large stones and leave it in place until temperatures climb above freezing. In fact, since it allows both light and air to penetrate, frost cloth can remain on top of the plants for weeks if necessary.
“I have overgrown shrubs that cover the bottoms of my windows. When can I prune them, and by how much?”
As mentioned earlier, save this pruning for the latter part of the winter. For most types of shrubs that would mean early February. If you use lopping shears so that you’re tailoring the shrubs back branch by branch you can reduce most types by 30% or 40% in height and width, some even more. The main warning would come with conifers such as junipers and arborvitae (not used much in recent years). Those types don’t have the ability to send out new growth from their old stems. If you remove all of the green growth on big parts of those plants, you’re likely to lose them.
“I’m planning on keeping my tropical hibiscus and bougainvillea plants in the garage over the winter. Is there anything special I need to know?”
I’d be tempted to warn you not to do this. I’ve never seen a garage that was warm enough or that had enough light to maintain these plants in any manner of vigor over an entire winter. They both go downhill if they don’t have full sunlight and if temperatures drop below 50F. If you have a way to use a plant dolly to shuttle them in and out on the good days, you’ll have a much better chance of pulling them through. Otherwise, it may be less frustrating just to buy new plants come spring.
“I have a very nice volunteer red oak tree that came up in our backyard. I have a spot where I really could use it. When and how can I move it? It’s about seven feet tall.”
Transplant it while it is completely dormant — after the first hard freeze and by mid-February. Given that height, I’ll assume that its trunk is a little less than 1 inch in diameter. If so, a soil ball 12 to 14 inches in diameter and 10 or 12 inches deep would be ideal. Use a sharpshooter spade to cut the roots and form the ball of soil but do so gently and patiently. Nurserymen would wrap the ball in burlap, but if it holds together well you wouldn’t have to do that. Lift the tree carefully by the soil ball and transport it to its new planting site. Have the hole ready for it, dug so that it can be set in at the same depth at which it was growing before. Set it in place carefully and sift loose soil around to hold it perfectly upright. Water it slowly and thoroughly, then add more soil to eliminate all pockets of air. It’s probably not tall enough to need staking. However, to be on the safe side, I would still apply paper tree wrap to its trunk for the first year to protect against sun scald since it will be so exposed.