If it’s controlled, Mexican petunia is delightful
Q: What is this plant with the purple flowers? It has invaded my flower bed. More importantly, how can I get rid of it? It’s spreading like crazy.
A: It’s Mexican petunia, Ruellia brittoniana. You’re right on its invasive nature. However, kept in bounds by use of concrete boundaries, etc., it’s a handsome perennial. It’s just too bad when it invades.
You’ll need to remove it physically (shovel, unfortunately), then install a root barrier around either the bed where you don’t want it or the bed where it’s currently growing. If you don’t have any of it growing in your yard, it may be coming from seed from a garden nearby, in which case you’ll have to eliminate it as the seedlings sprout.
Q: I bought some Daisy May daisies last spring and they did wonderfully. By the end of the summer some of the leaves were starting to turn brown. What should I do?
A: Most Shasta daisies have a few issues after continuous weeks in the Texas heat. Your plants look relatively fine, and if you were happy with their performance last spring, I’d just keep them tidy this fall and prepare for an even better show come spring since they’ll be so much better established. Trim out the browning stems and foliage as they appear.
Q: I am wondering why I had no flowers on my okra this summer. After an onion crop in early spring, I used soil from my composter, cotton bur compost and manure. I fertilized it twice and watered every couple of days.
A: I’m wondering if the plants might have been starved by all that organic matter. If you have too much fresh organic matter, nitrogen can be tied up and unavailable for use by the plants. That doesn’t mean you want to apply excessive amounts of nitrogen. You can use the amount of new growth on the stems as your indicator.
I’m also assuming the plants were in full sun. That would be a requirement.
Q: I bought some St. Augustine sod for shady areas in the hopes I could stop erosion. What isn’t already dead is sending up vertical shoots. It is producing no runners along the ground. I see no visible insects or diseases, and the lawn is irrigated. Where have I messed up?
A: Remember that to grow successfully, St. Augustine requires at least five or six hours of direct sunlight daily. It sounds to me like your sod didn’t get anywhere near that amount. That’s exactly the behavior St. Augustine will show when it’s in too much shade.
I’ve seen it happen with sod in my own lawn. It’s probably time to shift over to a shade-tolerant ground cover.
Q: I have two 5-year-old Savannah hollies planted on the west side of our house. They receive shade part of the day but a lot of afternoon sun. They haven’t grown much at all, and now their trunks have started splitting. Why might that be happening?
A: Savannah hollies are more particular about soils and exposure than some other holly varieties. For example, they are absolutely not suited to alkaline soils, so they are limited to just the eastern quarter of Texas.
For some reason, nurseries carry them in areas where they’re not suited, and it takes five or 10 years for them to start showing signs of failing. Trunk damage due to bark splitting is one symptom, but iron deficiency and lethargic growth are more common.
Oakland hollies are also fairly upright, and they are far more adaptable. I believe they would be better solutions in the long run. Water them by hand, however, for their first couple of years to get them established.
Q: I was surprised to see borers attacking my Acoma crape myrtles. What type of borer is this? Is it something you’ve seen?
A: It is not. I suspect it’s just some type of insect that got behind the exfoliating bark on the crape myrtle’s trunk and made its way around. I work with crape myrtles several days a week and am quite familiar with their problems. This is not a common one.