My days are filled with questions that go like this: “Neil, what’s the best time to …?” and “Is this a good time for ...?” I’m glad to hear it because only half of our success as North Texas gardeners depends on doing the right things, and the other half comes from doing them at the right times.
And because there are so many September garden chores that will have a great impact on how our gardens will look next year, I’ve assembled a list of answers to timing questions most pertinent to fall gardening — and to what you should be doing in your yard this month.
Planting wildflower seeds
If you’re in the market for wildflowers, early September is the time to sow bluebonnets and other spring types. They germinate with fall’s rains, grow and establish over the winter, then bloom as spring unfolds. Too many people think of sowing wildflowers in February or even March, just as they begin to show flower buds.
Plant bluebonnets into lightly tilled soil that is free from competing grasses (and most especially, not into turfgrass). In nature you’ll usually find them growing in rather forsaken soils, so be extremely stingy with the fertilizer. Simply provide adequate moisture to help them grow. Use acid-scarified bluebonnet seeds for the best results.
Growers like Wildseed Farms in Fredericksburg will be your best sources. The acid treatment breaks through bluebonnets’ hard seed coats so that moisture can get into the seeds. Scarification improves germination greatly.
Digging and dividing spring-flowering bulbs
If you have spring bulbs like jonquils, narcissus, species tulips and grape hyacinths, chances are they’ve become overcrowded by now. Dig and divide them in early September, before they start establishing new roots for their next spring bloom. For spring-blooming perennials like iris, daylilies, Shasta daisies, coneflowers and violets, dividing bulbs is best done in late September and into early October. If you end up with extra plants, give them to friends or put them in the compost. Don’t overcrowd your re-plantings.
To encourage wisterias to bloom more prolifically, use a sharpshooter spade to cut a “trench” (more like a vertical slice) around the trunk, 15 to 18 inches out. By severing the surface roots 8 or 10 inches deep, you may shock the plant into setting more flower buds.
If your goal is to prepare a tree or shrub for transplanting this winter — the only good season to dig and relocate woody plants — you should use the same technique as with the wisteria, only stay a little farther out from the trunk if it’s a large plant that you intend to move. By root-pruning it now, you give it months to establish new roots within the eventual soil ball and improve your odds of a successful move.
When the goal is to stop the spread of roots toward your house’s foundation, driveway or patio, cut a trench 4 inches wide and 24 inches deep. Install a root barrier — vinyl pond liner works nicely — to contain the new root growth. Late September is your timeline, since temperatures are dropping then and the plant’s need for large amounts of water is declining.
Pruning overgrown shrubs or unsightly perennials
This is more of a plant-by-plant situation, but you can always tidy things up wherever it’s needed. If you have shrubs that have really bizarre branches, trim them off now. If you have perennials with spent flower stalks or dead shoots, you can prune them off now.
By comparison, if you need to remove 60 or 80 percent of the height and width of a planting of shrubs, that really needs to wait until late January or early February — just before the burst of new growth for the spring. That kind of heavy pruning will stimulate new growth, and you don’t want that to occur going into the winter. Nor do you want to look at the bare branches and stubble from now until spring.
Planting new lawns
This question comes up every week, but I never get tired of repeating my answer. In September, planting new turf should be a priority for all North Texas gardeners. Bermuda seed should be planted immediately. St. Augustine sod should be laid no later than mid-September. Bermuda and zoysia are slightly more cold hardy, so their sod can be planted anytime before the end of the month.
The problem is that it’s going to start getting cooler, and grass roots won’t develop rapidly. Our first freeze could be as early as seven or eight weeks from now.
Applying fall pre-emergent granules
I discussed this in a past article, but it also bears repeating. The deadline for treating turf with pre-emergents has arrived. Apply Team, Dimension or Halts to prevent weeds like annual bluegrass, rescuegrass and ryegrass. Apply Gallery to stop germination of henbit, clover, chickweed and dandelions. And do it as soon as possible. You have no more time to wait.
Note: Some of these products may not be available in national chain stores, so shop at local nurseries and hardware stores instead. They will be able to help you. Mow. Apply one type and then the second type. Water moderately. They are safe on any type of lawn as long as it has been through at least one winter.
Neil Sperry publishes Gardens magazine and hosts “Texas Gardening” from 8 to 10 a.m. Sundays on WBAP/820 AM. Reach him during those hours at 800-288-9227. Online: http://neilsperry.com.