September is a game changer in Texas. It may not look or feel like fall when the month begins, but gardeners know better. The days are getting shorter, the nights are gradually getting longer, and sooner or later the first cool front will come rolling through. After months of heat, drought, watering, sweating, and wondering why we ever chose gardening as a hobby, September gives us hope again. More importantly, September marks the beginning of one of our most important planting season. It truly is a second spring in Texas.
Gardeners who moved here from colder parts of the country often think of spring as the only planting season. In Texas, fall is often even better. Our winters are generally mild, our soils stay warm long after the air cools, and many plants can spend fall, winter, and early spring developing roots before having to face another blistering Texas summer. September is when we start making that transition.
One of the first places to get busy is the vegetable garden. The fall vegetable garden is often easier and more productive than the spring garden. Instead of watching temperatures get hotter every week, we watch them get cooler. Many of our favorite vegetables are cool-season crops that tolerate frosts and actually produce better quality during cool conditions.
September is time to start planting seeds of beets, carrots, cilantro, collards, lettuce, mustard, radishes, spinach, Swiss chard, turnips, and other leafy greens as temperature and rainfall allow. Some seeds germinate poorly in hot soil, so timing and moisture are important. Keep newly seeded beds consistently moist until the seedlings are established. A light layer of mulch between rows can help conserve moisture, but don’t bury tiny emerging seedlings.
It is also time to set out transplants of broccoli, cabbage, cauliflower, collards, kale, and other cole crops. Transplants are generally best for these because they give you a head start and help you beat the calendar. Unlike spring gardening, where summer heat eventually shuts things down, fall gardening is a race against decreasing temperatures and shorter days. Make sure and saturate them with a water-soluble fertilizer when you plant them.
Fall lettuce
September is also an important month for planting spring-blooming perennials. This sounds backward to gardeners accustomed to buying plants while they are blooming, but planting before bloom time is almost always better. A perennial planted during fall has months to develop roots before it is expected to flower. This is especially useful with spring-blooming perennials. Columbines, coneflowers, coreopsis, phlox, penstemons, and many other hardy perennials benefit from fall establishment. Some may not look like much during winter, but underground they are getting ready. When spring arrives, established plants can devote their energy to growth and flowering instead of trying to grow roots, leaves, and flowers all at once.
Texas Gold columbines
September also begins one of my favorite gardening activities, sowing wildflowers and reseeding annuals. If you want spring wildflowers, you generally don’t plant them in spring. You plant them in fall. Think about how nature does it. Spring wildflowers bloom, produce seed, and scatter that seed onto the ground. The seed waits through summer and then responds to cooler temperatures and fall and winter moisture. Many species germinate during fall, spend winter as small rosettes, and then take off when spring arrives.
Bluebonnets are the classic Texas example, but they are certainly not alone. Indian paintbrush, Drummond phlox, coreopsis, larkspur, poppies, and many of our beloved spring wildflowers and reseeding annuals follow some version of this schedule. September and October are the months to get many of these seeds on the ground.
One of the biggest mistakes people make with wildflowers is scattering seed into thick turf or on top of mulch and expecting a meadow to appear. Seeds need contact with the soil. Existing vegetation must be reduced, leaves and heavy mulch removed, and the seed pressed or lightly raked into the soil. Most wildflower seed should not be buried deeply. Nature doesn’t own a rototiller.
Spring wildflowers and reseeding annuals
And then there are the permanent members of the landscape. As temperatures begin to moderate, we enter the best season for planting trees, shrubs, and hardy woody vines. There is an old horticultural saying that fall is for planting, and in Texas it is particularly good advice.
A tree planted in spring may have only a few weeks before it encounters its first spell of brutal summer weather. A tree planted in fall can have months to establish roots before facing that same challenge. Even though the top of a deciduous plant may go dormant, roots can continue developing whenever soil temperatures are favorable. The same principle applies to shrubs and vines. Azaleas, camellias, hollies, hydrangeas, roses, viburnums, native shrubs, and many other woody ornamentals benefit from fall planting. Hardy vines such as American wisteria, Carolina jessamine, coral honeysuckle, and crossvine can also get established during the cooler months and be ready to grow vigorously the following spring.
For shade trees, there is no need to improve the planting hole with a bunch of amendments. Dig a wide hole no deeper than the root ball, plant at the proper depth, and backfill with the native soil. The top of the root ball should be level with or slightly above the surrounding grade, never buried beneath it. Mulch over the root zone while keeping mulch away from the trunk or stems. And don’t forget to water. All plants of any kind should be watered well after planting. Newly planted trees, shrubs, vines, perennials, and vegetables all have limited root systems and can dry out quickly. September can still be brutally hot and dry in Texas. The advantage of fall planting comes after establishment, not instead of establishment.
Planting a tree
September is really two seasons rolled into one. Summer is still hanging on, but fall is knocking at the door. Our warm-season plants are still blooming and producing, hummingbirds and butterflies are passing through, and the landscape may still look thoroughly summery. Meanwhile, gardeners are sowing seeds and planting plants for vegetables in fall and winter, flowers next spring, and trees that may shade somebody decades from now. That’s what makes September such an exciting month in a Texas garden. We aren’t just tending what we have. We are planting what comes next. Times are changing so take advantage of it.
