A few questions to keep in mind as you work to improve the look in your garden

Some questions defy answers. “How large is the universe?” “Why was it so hard for me to find a date?”

And there are some in horticulture that are just as hard for inquiring minds to process. Those are going to be the focus of our words here today as I do my fly-by attempt at giving them answers.

What is the best fast-growing shade tree?

“Fast growth” and “quality shade trees” are mutually exclusive terms. All of the fast-growing trees have at least one fatal flaw. They all have weak wood, and that makes them susceptible to a wide variety of insect and disease problems. All have short life expectancies. However, to give you an answer, if I had to choose one fast-growing shade tree for my own landscape, I guess it would be a fruitless mulberry. For those of you who are now groaning, that just proves my case.

How often should I be watering my plants?

I have an answer for you, but I’m going to save it for just a moment. Several facts will determine your own exact answer. They include the types of plants, their rates of growth, the types of soil, sun exposure, wind speed and temperature, among others. But the real answer to the question is the frequency will vary greatly. You are going to have to learn how to determine when it’s time to water. Learn to recognize symptoms of drought. Let your plants tell you when they are needing water. Some will wilt. Others will change colors. Others may not have any visible signs at all. You’ll have to learn to feel the soil.

Why did my plant die when neighbors on both sides of me have the same kinds of plants and theirs are doing just fine?

This one is just too open-ended. You need to teach yourself not to look at the neighbors’ plants! Their soil may be different. The exposure to sunlight and reflected heat may not be the same as yours. They may have watered slightly differently or fertilized their plants slightly better. All you can do is to give your plants the best possible care and hope that they will perform well for you.

What perennial can I plant for color for years? I’m tired of having to replant annuals every year.

To answer this one, I have to adjust people’s way of looking at perennials. All perennials have one peak season of bloom. For almost all of them, it will come over a two- or three-week period. Outside of that time they will not be especially attractive. It’s imperative for the perennial gardener to have 15 or 20 types of plants for a succession of blooms. The truth is, perennial gardens are actually as much or more work than gardens of annual flowers.

What’s wrong with my St. Augustine? It looks terrible. I think it’s dying.

This is a tough one. At this time of year, in the heat of the summer, St. Augustine is most commonly troubled with chinch bugs and gray leaf spot. Chinch bugs will cause the grass to appear dry in hot, sunny areas. Irrigation will not help, however. Close inspection will reveal the BB-sized black insects. They can be controlled with several readily available insecticides.

Gray leaf spot causes the grass to develop an overall yellowish cast. Close inspection of the blades will show small, diamond-shaped lesions. This fungus is exacerbated by applications of nitrogen in the summer. Control it with Daconil or Azoxystrobin fungicides and do not apply fertilizer between mid-June and early September.

How long until I can plant new rose bushes where rose rosette virus killed the old ones?

The virus does not persist in the soil. In theory you could replant almost immediately. However, there is great likelihood that other rose plants in your neighborhood are also infected. If so, the microscopic mites that brought the disease to your plants initially could bring it right back to your new plants. As long as you replant with the knowledge that your new plants may not last indefinitely, and if you’re careful to select plants that are not infected at the time that you buy them, you could give it a try. However, many of us are limiting the number of roses that we plant until some of the mysteries get sorted out.

Why do people persist in topping their crape myrtles? Haven’t they heard that it ruins the plants’ natural shape and does nothing to help them bloom better?

I have to admit that I’ve added this question in for my own pleasure. Like a pastor who tries to teach us the ways to be better humans, I’ve spent a career trying to teach the ways not to prune crape myrtles. “Topping” is at the top of that list! I feel like progress has been made, but it appears that I need about five more careers to finish the task. Indeed, that is a truthful statement. Topping ruins crape myrtles.

You can hear Neil Sperry on KLIF 570AM on Saturday afternoons 1-3 pm and on WBAP 820AM Sunday mornings 8-10 am. Join him at www.neilsperry.com and follow him on Facebook.