Neil Sperry

These are the most pressing questions of early fall gardening

Carlton daffodils are a sign of spring's arrival this week in the Sperry home gardens.
Carlton daffodils are a sign of spring's arrival this week in the Sperry home gardens. Special to the Star-Telegram

Gardeners are a curious sort. They have about as many questions as youngsters, but the adults’ are more difficult. I’ve put together a list of the ones that keep coming up as summer transitions into the fall.

Is it too late to treat for chinch bugs?

Yes. They are hot-weather insects and their damage for this year has already been done. They show up between mid-June and the end of August.

What’s the best “winterizer” fertilizer?

Actually, you want to use the same fertilizer you should use the rest of the growing season. That would be an all-nitrogen food that has a significant percentage of that nitrogen in slow-release form. If you’re in an area with sandy soil, tests may suggest that you use a high-nitrogen food. Again, look for one with a high percentage of slow-release N.

Is it too late to plant new grass?

No, but don’t delay. It actually might be a bit risky to plant St. Augustine now, depending on how early the first freeze hits. We’ve had years where it happened as early as late October. Bermuda and zoysia sod should still be fine, but don’t delay.

Why are my pecans falling early?

Pecan scab. They’re probably also turning black on the outside and watery on the inside. It’s a fungal disease that must be controlled with fungicidal sprays beginning in late spring and continuing through the summer.

Can I remove exposed tree roots now?

Yes, but only in moderation. You may want to have a certified arborist do this for you to be sure you don’t take off more roots in any one year than the tree can tolerate. Consider planting a groundcover to conceal them instead. Some trees such as live oaks naturally produce large surface roots.

Why are so many of my trees dropping their leaves already?

It could be caused by several things. Likely it’s the result of the hot, dry summer weather. It could be caused by honeydew residue from aphids or other insects, or the trees may have some type of disease that’s impacting them.

What can I do to get rid of the ugly webs in my trees?

Use a long-handled pole pruner to clip them out before they become unsightly. They won’t do serious long-term damage to the trees, but they are certainly unattractive. Sprays are tedious to apply and very inefficient.

Can I prune my trees now?

Yes. Prune to remove dead or damaged branches. Prune, too, to remove hazardous or unwanted branches that may be blocking views. This is even the proper time to prune oaks, since oak wilt is less likely to be spread at this time. Seal all oak cuts with pruning paint, but do not apply pruning sealant to other species.

Is this a good time to plant new shrubs?

Nurserymen (and I) will tell you that fall is the very best time to plant new shrubs and trees. This gives them the longest possible time (6 or 7 months) to establish new roots before next summer’s heat rolls in. Add to that nursery plants are large and full right now, and many nurseries are also beginning their fall sales.

How far back can I trim shrubs that have grown too tall, and when should I do it?

That depends on the species and the plants’ inherent vigor. Generally however, you don’t want to remove more than 25 to 30 percent of the top growth at any one time. Prune them branch-by-branch so you can maintain a natural growth form. Mid- to late winter would be the best time, since they’ll regrow and fill in very quickly thereafter.

When do I dig and divide my perennials?

Spring-flowering perennials are dug and divided in fall (late September through October). Fall-blooming types are dug and replanted in very late winter, before the spring growth begins.

How do I care for my new mums that I’m planting?

They will be in bloom for several weeks. As the flowers change to tan you can trim them off. Actually, you can cut the flowering stems back to about 2 inches. You’ll probably notice new shoots emerging near the soil line. Those will be next year’s stems. Just leave them in place and mulch around them for the winter. Keep them moist and they’ll be fine. You may even see a few weeks of blooms next spring.

What are the most dependable types of daffodils and tulips?

Choose small- and early-flowering daffodils and narcissus. Carlton and Ice Follies are two of the all-time favorites to establish and rebloom year after year. As for tulips, almost all are hybrids that have been bred for colder climates. They do not come back to rebloom in successive years. In Texas the best types for establishing and reblooming are species types. Their flowers are smaller, but their garden display is outstanding. You may find them in nurseries, but more often than not you’ll end up having to order them online.