Late Winter Best Time To Trim Texas Mountain Laurel
Neil Sperry
DEAR NEIL: Can I trim a Texas mountain laurel that grew lanky due to excessive shading? I have pruned the trees that were casting the shade.
Yes, you can reshape the plant as needed, although the best time to do major pruning would be in very late winter, before the new spring growth. Do whatever trimming you feel you can do now. Watch the trees, too. They will probably grow right back where they were before.
DEAR NEIL: How can I get rid of monkeygrass that is taking over its bed around my shrubs?
You could probably kill it with a weedkiller, but then you’d have to look at the stubble for years. You’d be far better off to give it to someone who needs a great shade-tolerant groundcover. If there is any way for you to install 4-inch edging to its full depth, it will prevent the spread of the monkeygrass where you don’t want it.
DEAR NEIL: What causes the brown discoloration around the edges of rose petals? When the buds finally open, the inner petals are fine.
That’s thrips. Peel one of those buds open, and you’ll see nearly microscopic insects scurrying around near the bases of the petals. They have piercing-sucking mouthparts, and they attack many of our flowering plants. You’ll also see them in almost every magnolia and gardenia bloom.
Use a labeled systemic insecticide every 10 to 15 days to stop them.
DEAR NEIL: I cannot grow petunias, in spite of all the care I give them. I buy healthy plants, but then they wither and die. The stem tissues seem to have been eaten by some pest. All that is left is a hollow stem. I see a thin, white worm sometimes hanging from the holes in the stems. I have used sevin and other insecticides, to no avail. What can I do?
Petunias are bothered by several maladies. You have some type of larval insect (there are 4 or 5 types that will show up on petunias and their relatives). In the chance that they’re loopers of some sort, try Bacillus thuringiensis biological worm spray or dust. Sevin will not work on that category of larvae. Pillbugs will chew away external stem tissues much like miniature beavers. If you’re seeing that, dusting the plants and the soil with sevin would help. And, the other common petunia problem is the same soil-borne water mold fungus that attacks pansies, snapdragons and other plants. It will leave the stems looking pinched and dried. That does not sound like what you have, but, if it ever does show up, your best remedy is to bypass those several susceptible species for several years.
DEAR NEIL: How do you get purple sages to grow thicker and not be see-through thin? If pruning is involved, how much and when?
Begin by assessing the sunlight. Purple sage requires full sunlight. If it gets more than a very few hours of shade, the plants will grow tall and lanky, and all the pruning you might do won’t make up for it. On the other hand, if the plant is planted in full sun, and if it’s still thin, you can certainly trim it to encourage fuller growth. Late winter is the best time if you need to remove more than 10 or 15 percent of the top growth.
DEAR NEIL: Attached is a photo of a cart full of briar tubers. If I cut them off at the ground, they still come back. Is there an easier way?
You are the first person ever to refer to these plants’ fleshy roots properly, that is, as tubers. Good work. The plant’s common name is smilax. Many of us who have them have discovered that cutting the plants off at the ground will eliminate a certain percentage of the population (usually most of them). Those plants that do resprout can be removed physically by digging the tubers. It takes a minute or two per plant, but it’s permanent. Because of the plants’ sparse and extremely glossy foliage, herbicide sprays are of little value.
DEAR NEIL: What will encourage crape myrtles and geraniums to bloom?
Both plants produce their buds on new growth. Both would do best if given a high-nitrogen fertilizer several times during the spring and into early summer. Geraniums do play out once it gets hot.
DEAR NEIL: What is the best screen for a small back yard? I would prefer something that flowers, but I don’t have a lot of room. I do not want it to be poisonous, as I have pets and children.
My choices, given those limitations would probably be from standard glossy abelias, standard heavenly bamboo nandinas or elaeagnus. I also have pets and grandkids, and I have used willowleaf hollies for this same function.
It would be my own first choice, but its berries, like all hollies, are mildly irritating or toxic. But, then again, so are many of our other popular plants: azaleas, Carolina jessamine, oaks, tulips and daffodils and others. It’s more important that we teach our kids not to graze in the garden than it is that we avoid plants that might be somewhat toxic. Pets will take care of themselves.
DEAR NEIL: How much should I prune my hydrangeas after they finish blooming? I do not want to hurt next year’s flowers.
It’s not required that you prune them at all. About all your really need to do is to reshape the plants as needed.
DEAR NEIL: I have a 9-year-old eastern redbud tree that is starting to lose entire lower branches. The leaves are yellowed with dark green veins. I do not see cankers, but I’m concerned about verticillium wilt or some other disease. More, I am concerned with my oak and mountain laurel that are 20 and 30 feet away. What advice do you have?
I would start by taking a handful of really clear photographs of the entire tree, along with samples of the leaf discoloration to a Texas Master Certified Nursery Professional in your neighborhood. That will be a highly skilled, veteran nurseryman who will able to tell you if it’s a simple issue with something such as weedkiller injury or a gas leak. Iron deficiency certainly causes the leaf discoloration you described, but it doesn’t begin at the bottom of a plant, but, instead, at the top. And, you will almost never see redbuds with iron deficiency. Look, also, for signs of redheaded wood borer invasion. The adults look like two-thirds-sized yellow jackets with burgundy red heads. The exit holes they leave in the trunks of redbuds and silver maples, among other trees, are pencil-lead-sized. As for other, much more exotic disease issues, you would want to send samples to the Plant Disease Diagnostic Laboratory at Texas A&M. Contact your local office of the Texas AgriLife Extension. It may comfort you to know that redbuds’ average life expectancy is probably 25 to 35 years. While that’s a lot older than your tree, it does suggest that things do happen to them. Finally, what impacts redbuds will usually not bother other, unrelated plants. The exception, of course, would be if there is a weedkiller or gas issue in the area.
DEAR NEIL: I have a 5-year-old buckeye that I grew from a seedling. It is now approximately 6 feet tall. It has bloomed the past several years, and it has produced several small buckeyes, but they have just shriveled up and fallen off. What is wrong?
It’s probably not mature enough. That’s not a very old tree, so the odds are that it can’t sustain fruit just yet. Give it another year or two and it probably will be able to produce mature buckeyes.
DEAR NEIL: I have two weeping willows, one hybrid poplar and a river birch tree, and they’re all fairly close to one another. The willows and poplar are two years old, and I’ve had the birch for one year. Now, all of their leaves are turning brown. The problem started very quickly. Could it be too much water? Not enough?
Those are all very problematic trees. Any time you choose for fast growth, you’re inviting serious troubles. Willows are our shortest-lived trees (probably tied with purple-leafed plums). They’re highly susceptible to cottonwood borers. Poplars are cottonwood sisters, so they’re obviously susceptible, too. These are large insects that are almost impossible to prevent or control. River birch, where they’re adapted in deep East Texas, are satisfactory trees, but they, too, bring a lot of insect problems. The fact that four young trees developed problems at an early age and simultaneously, however, also suggests the possibility of a weedkiller or weed-and-feed fertilizer doing damage to them. Unfortunately, browned leaves aren’t much of a clue to get to the next level of answer. Take a closer look, then take samples to a nurseryman. It’s certainly not going to be due to too much water with that group of trees, and it probably isn’t too little water this early in the warm season.
DEAR NEIL: I live near a lake, and we always have fish parts. I’d like to know the best way to turn these into fertilizer, but I’m concerned about composting them due to rodents. Is it possible?
Probably so, although it’s a science of its own. Native Americans taught early settlers to bury the fish parts. It would seem that, if you could grind them as fine as possible, that the rodent issue wouldn’t be a major problem. Or, perhaps you could design some type of heavy wire covering to go over the compost bin until they had decayed sufficiently. Layer them in with several inches of loose organic matter such as dried tree leaves to confine the odors. In all honesty, while this is a great question, it’s certainly not my area of expertise.
DEAR NEIL: Most of my plums have worm holes. What can I do to stop them?
You need to follow the Texas A&M Homeowner Fruit and Nut Spray Schedule.
It’s normally found online at the TAMU Horticulture website, but it is undergoing revisions of product recommendations. However, there is nothing you can do at this point. These are plum curculios, and the sprays to prevent them begin while the plants are just starting to bud out. Follow the TAMU spray recommendations carefully. If you don’t, the larvae are almost inevitable.
Have a question you’d like Neil to consider? Mail it to him in care of this newspaper or e-mail him at mailbag@sperrygardens.com. Neil regrets that he cannot reply to questions individually.
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