For gardeners in Wimbledon Estates, September is less about putting the garden to bed and more about getting it ready for another growing season.

Houston-area summers can leave lawns tired, flower beds stressed and gardeners themselves ready for cooler weather. But as September begins, Harris County Master Gardeners say the changing season brings a surprisingly long list of opportunities — from planting vegetables and wildflowers to dividing perennials, caring for roses and getting landscapes ready for fall.

One piece of advice applies across much of the yard: before automatically reaching for the hose, check the soil.

Master Gardener Karen Shook recommends remembering the simple question of whether the soil is “too wet, too dry or just right,” then watering accordingly. When water is needed, a thorough, deep watering generally does more good than frequent shallow watering.

That can be especially important during September in the Houston area, where summer-like temperatures can linger even as gardeners begin preparing for fall.

September Opens a New Gardening Season in Harris County

The guidance comes from the Harris County Master Gardeners, volunteers trained through the Texas A&M AgriLife Extension Service to help residents make gardening decisions using research-based horticultural information.

The local organization does much more than publish seasonal gardening advice. Harris County Master Gardeners answer questions from the public, maintain testing and demonstration gardens, provide educational programs and workshops, support youth gardening programs and hold plant sales that help fund horticultural education.

They are part of the statewide Texas Master Gardener program, in which trained volunteers work through local AgriLife Extension offices to share horticultural knowledge within their communities.

Texas A&M AgriLife Extension itself has served Texans for more than a century, providing science-based education involving agriculture, natural resources, horticulture, health and other areas through a statewide network of educators, volunteers and county offices. Harris County is among the counties with its own Extension office and locally focused programs.

For homeowners in Wimbledon Estates, having advice tailored to Harris County can make a real difference. What works in another part of the country may not work the same way here, where gardeners deal with long stretches of heat, mild winters and local soil conditions.

What Flowers and Perennials Can Be Planted in September?

Gardeners ready for some fall color can begin with chrysanthemums. Newly planted mums can be fertilized every two to three weeks until flower buds appear, then weekly until those buds begin showing color.

September is also a suitable time for planting perennials, ornamental grasses, groundcovers and vines. Preparing the soil before planting gives those additions a stronger start.

Established landscape plants can receive fertilizer during September as well, after which fertilizing can generally pause until February.

Some spring-flowering perennials can also be divided now, including daylilies, calla lilies and irises. Gardeners looking to divide Shasta daisies, gaillardia or cannas should give the weather a little more time to cool.

For annual color, seeds for cool-season favorites such as snapdragons, stock, calendula and alyssum can be started now. Seedlings are generally ready for transplanting in about six to eight weeks, with hardening off beginning once the plants develop two sets of leaves.

Pansies can also be planted for color that can carry through the cooler months and into spring.

Do Tulips and Hyacinths Need Refrigeration in Houston?

Yes — and September is the time to remember them.

Tulip and hyacinth bulbs should be placed in refrigeration by late September so they receive the chilling period they need before being planted in December.

That extra step is important in the Houston region because winters do not reliably provide the prolonged cold temperatures these bulbs would naturally experience farther north.

September Rose Care: One More Pruning Window

Gardeners who did not prune repeat-blooming roses in late August still have an opportunity in early September.

Harris County Master Gardener guidance recommends reducing the plants by about one-third, or to the desired height, with cuts made just above a bud.

Dead wood, diseased canes and small twiggy growth should also be removed.

After pruning, roses should be fertilized and watered, while gardeners who follow a regular fungicide program should continue that schedule.

Once-blooming rose varieties are an exception and should not be treated the same way.

Harris County Soil Can Be a Challenge for Azaleas and Camellias

September is also a useful time to pay attention to something residents cannot see simply by looking at their flower beds: soil pH.

Many landscape plants prefer slightly acidic conditions, while soils in Harris County tend to lean alkaline. Gardeners growing acid-loving plants such as azaleas and camellias may need to amend the soil appropriately.

Rather than guessing, testing the soil can help homeowners make more informed decisions about whether changes are actually needed.

Shrub beds intended for October planting can also be prepared during September.

Gardeners who have favorite plants they would hate to lose during a severe winter can take semi-hardwood cuttings in early to mid-fall. Those cuttings can be propagated as backups — or shared with neighbors and friends.

Red-tip photinias that are sheared early in September may also respond with colorful new growth once cooler weather arrives.

September Is Bluebonnet Planting Time

Anyone hoping for bluebonnets next spring should be thinking about them well before spring arrives.

Early fall is an appropriate time to sow bluebonnet and Indian paintbrush seeds.

Scarified bluebonnet seed — seed that has had its tough outer coating treated or scratched to encourage water penetration — tends to germinate faster. After broadcasting seed, gardeners can gently rake it into the soil.

It is one of those gardening chores whose reward comes months later, when a small patch of Texas color begins appearing in the landscape.

What Should Homeowners Do for Their Lawn in September?

Bare or dead spots in the lawn can still be repaired with sod or plugs. Loosening the soil before installing them can help roots establish.

September is also traditionally the time for applying a winterizing lawn fertilizer, although that application can extend into the first week of October.

As with other fertilizers, homeowners should follow label directions and avoid the temptation to assume that more product will produce a better lawn.

Fall Vegetable Gardening May Be September's Best Opportunity

For gardeners who think vegetable season ends with summer tomatoes, Harris County Master Gardener Jo Ann Stevenson makes a compelling case for giving fall gardening a chance.

She prefers fall gardening for several practical reasons.

For one, it is simply more comfortable to work outside once temperatures drop below the worst of the summer heat. Cooler weather also benefits vegetables such as lettuce, which is less likely to bolt — sending up a flower stalk and bringing leafy production toward an end.

Some familiar warm-season garden problems begin easing as well. Squash bugs, tomato hornworms, spider mites and other summer pests tend to become less troublesome as temperatures fall, while lower humidity can help reduce some plant diseases.

Then there is flavor.

A light frost can actually improve some greens and root vegetables. Cabbage, Stevenson notes, can develop better flavor after experiencing a “frost kiss.”

What Vegetables Can Be Planted in Harris County This Fall?

Once temperatures begin moderating, September opens the door to many cool-season vegetables.

Gardeners can consider varieties of lettuce and other greens along with green beans, peas, radishes, carrots, beets, turnips and cauliflower.

And cauliflower can be considerably more interesting than the familiar white heads at the grocery store. Varieties can include green Romanesco types, orange cauliflower such as Cheddar and purple selections such as Purple Moon.

Timing still matters.

Gardeners should check the number of days to maturity printed on seed packets and avoid planting so late that an early freeze could arrive before crops are ready for harvest. The Harris County Vegetable Planting Guide can provide more specific planting windows for local conditions.

September can also be a good time to plant strawberries when plants are available, with soil fertilized before planting.

Herbs Can Carry the Garden Into the Holidays

A fall herb garden can also become surprisingly useful once holiday cooking begins.

Parsley, sage, rosemary and thyme generally perform well during the fall and can find their way into turkey, dressing, gravies and other seasonal dishes.

Basil, oregano and chives may continue growing until the first frost, while cilantro prefers the cooler weather that arrives later in the year.

Gardeners with more herbs than they can immediately use can chop them and mix them into butter, then freeze the herb butter for later use.

Nasturtiums are another cool-weather option. They grow well as temperatures ease, their flowers and leaves are edible, and the plants can attract aphids while helping repel some other pests.

Fall is also garlic-planting season. Bulbs planted during fall can produce fresh garlic the following spring.

For residents who have never tried growing vegetables during the cooler months, fall may be one of Harris County's most forgiving seasons to experiment.

September Is Also a Good Time to Look Up

Garden preparation should not stop at ground level.

September falls within the historically active portion of Atlantic hurricane season, making it a sensible time for homeowners to inspect trees for dead, broken or damaged branches that could fall during strong winds.

Light pruning of selected lower or interior branches may also help more sunlight reach lawns and landscape plants below.

Major tree work, particularly involving large limbs or trees near homes and utility lines, is better left to qualified professionals.

A Practical September Checklist for Wimbledon Estates Gardeners

The biggest takeaway from the Harris County Master Gardeners' September calendar is that residents do not have to tackle everything at once.

A weekend might mean repairing a bare patch of lawn and checking trees. Another could be spent starting snapdragon seeds, sowing bluebonnets or preparing a vegetable bed. By late September, homeowners may be refrigerating tulip bulbs while watching newly planted fall vegetables begin to emerge.

Fall gardening in Harris County is not simply cleanup after summer. In many ways, it is a second chance at the growing season — one with cooler mornings, different crops and a fresh set of possibilities.

Stevenson's advice to fall gardeners is appropriately simple: “Have fun with your fall garden, try new varieties, play with your food, and keep learning, y’all.”

For local homeowners, that may be the best September gardening rule of all.

Residents looking for research-based answers to specific lawn, tree, vegetable or landscape questions can also turn to the Harris County Master Gardeners' Ask a Master Gardener program, which connects the public with trained volunteers providing university-supported horticultural information.

Stay tuned to My Neighborhood News for more seasonal gardening guidance, community resources and local updates that matter close to home.

By Tiffany Krenek, My Neighborhood News 

Tiffany Krenek has been on the My Neighborhood News team since August 2021. She is passionate about curating and sharing content that enriches the lives of our readers in a personal, meaningful way. A loving mother and wife, Tiffany and her family live in the West Houston/Cypress region.