Common questions about North Texas landscapes as fall begins and temperatures drop

Over the years I’ve learned a lot just by listening to the questions gardeners ask. I know that we just turned the page toward autumn a week ago, but as a gardener thinks things over, the perspectives change as temperatures drop. Here are several of the things I get asked at this time each fall.

“Will my Gold Star Esperanza and Mexican bird of paradise survive the winter planted in the ground in North Central Texas?”

Probably not. Both plants are winter-hardy through South Central Texas (San Antonio toward Austin), but as you come north on I-35 their chances fade. Add to that the fact that we’ve had some really cold spells in the past several winters. If you have them planted in protected corners of your landscape, or if you’re within the urban heat pockets of a major city in Fort Worth/Dallas, you might get lucky, but otherwise it’s best to consider them as tropical annuals that will need to be replanted each spring. You could also grow them in large pots and overwinter them in a greenhouse.

“Can I do anything now to get rid of grassburs next year?”

Not much. Keep mowing them to remove the burs. They are the seeds for next year’s crop. If you want to put the clippings in the compost, and if you’re willing to turn it often and leave it to decay for a couple of years, that might work. Your main course of action, however, will be to apply pre-emergent granules to your lawn at the proper time late next winter and again 90 days later in late spring. The timing should be one to two weeks before the average date of the last killing freeze for your area. For the Metroplex that date is around March 15-20, so the first application should be made between March 5 and 15. The second application would between June 5 and 15. You can apply Halts, Dimension, or Balan. Buy enough the first time that you’ll have your supply for the second treatment. Stores tend to sell down after the first round of applications. These are safe for use on any type of turfgrass, also around trees and shrubs. But timing is critical. Once the grassburs have germinated you’ll have no further options for control.

“I have several shrubs that need to be moved as I redo parts of my landscape. What is the best time to do so?”

Mid-winter, after the first hard freeze has put them into complete dormancy. That normally happens by mid-November. Keep a ball of soil intact around their roots and prune their tops proportionate to the quantity of roots lost in the digging.

“When should I dig and divide my spring-blooming perennials like iris, daylilies, Shasta daisies, purple coneflowers, and hardy hibiscus?”

The general rule of thumb for perennials is that those that bloom in the spring should be dug and transplanted in the fall (now). Those that bloom in the fall are best being transplanted in very early spring (before they start growing — February through early March).

“Can I plant new grass now?”

You take a real chance in doing so this late. Bermudagrass sod will take root and establish, but St. Augustine needs warmer conditions than we will have. Zoysias grow slowly, so I’d also wait until spring to plant them, just as you’ll do with St. Augustine. If you opt to wait until spring, you can certainly sow ryegrass now to keep from having bare soil all winter. Plant the seed soon and it will be well established before cold weather stops its development. When the weather turns hot in May the ryegrass will die and fade out. At that point you’ll be able to rototill lightly and plant your permanent warm-season grass.

“Can I mulch my tree leaves into my lawn?”

You should not. It would be too much organic matter for the soil to accept in such a short period of time. Bag the clippings and either put them into a well-functioning compost pile or use them as mulch beneath shrubs. There is a two- or three-week period beneath most tree species when maximum leaf drop will occur. For most types that will happen toward the end of October, but some types are responding to recent dry weather by shedding their leaves early. When you have a solid layer of fallen leaves on the ground, that’s the time to bag them rather than mulching them.

“Will I be able to keep my tropical hibiscus and bougainvillea in the garage over the winter?”

Most people who try that do so only one time. They find that their plants drop most of their leaves and are lethargic when spring arrives. Garages are usually too dark and frequently too cold. The plants would be much better off if they could be brought into a sunroom or put into a greenhouse. Some people even wheel them in and out of the garage when it’s going to be cold. That way they can get sunlight on the many warm winter days.

“Can I save my caladium bulbs over the winter? Would they be better off if I left them in the ground?”

The ground will freeze. They wouldn’t survive that. However, digging them and storing them indoors isn’t much better. As their leaves fall to the ground you need to dig the tubers and lay them out on newspapers to dry for a few days. Dust them with sulfur or a general-purpose fungicide, then store them in boxes one layer deep in dry sawdust. Keep them at 60 degrees and in a relatively dry environment. Don’t plant them back outside until Mother’s Day or later — they require very warm soil. As I mentioned in another answer, most people who try this once don’t try it again.