September Stepping Stones

September Stepping Stones to Success in the Garden

Although it’s often hot for the first week or two in September, the growing season has shortened considerably. Both the garden and gardener feel relief from the heat and sun. The next six weeks are the most enjoyable in the garden. If July and August have been cruelly hot, the shorter day length and cooler evening temperatures will stir plants for another round of blooming. Many times Panhandle gardeners feel they’ve been given the worst of weather conditions, but when it comes to fall, our weather is unsurpassed. Back in England, cold, cloudy and damp days are the norm while we bask in warm, sunny, low-wind days. English Isle gardeners would give their golden trowel award for our moderate autumn weather; a second gardening season much preferred to the hectic days of spring.

The garden in September takes on the first looks of the fall garden. The glorious mid-summer floral display is extended by cooling temperatures and in good years, September rains. Goldenrods are joined by asters and chrysanthemums. Dahlias and cannas continue to bloom and lantana plants become exuberant. The taller growing sedums flowers begin to open. Late season salvias come into full glory, joined by plumes from warm season grasses and crepe myrtles flowers. Annual and perennial vines such as hyacinth vine, black-eyed susan (Thunbergia alata), sweet potato and spanish flag vines (Ipomoeas) and sweet autum clematis reach their mature heights and flower, putting on interesting or colorful seed pods. Summer annuals, sub tropicals and tropicals continue to grow unless an early freeze occurs -- something increasingly rare. By mid-September, pumpkins and gourds are ready for the harvest and can be used as seasonal landscape decoration.

September can be quite a busy month what with fall planting, harvesting, seed collecting,  and reseeding chores throughout the landscape. But at least it's cooler, and alot less windy. Fall is an ideal time to plant. There is plenty of time for even warm season plants to become established enough before winter. Take out the notes made during the summer on editing bed compositions. Make these adjustments. The home improvement centers (not the nurseries) start to fill with plants again, and many times their plant selection improves in the fall. With one exception. Be careful of the plant’s cold hardiness and tight, root bound plants. This is also the time for growers and nurseries to dump their stock before winter. Beware of Spanish lavenders, some grasses and non cold-hardy perennials. Yes, Amarillo is in Texas, but we’re still not Houston’s Zone 8 or 9. I wish the New York corporate suits knew that. Plant buyer beware!

This is also an ideal time to plant seeds of cool season vegetables and transplant seedlings for the fall. Lettuces can be started (if not started already) as soon as the two inch soil temperatures cools -- usually right after Labor Day, even in a hot year. The first cut harvest of lettuce is only thirty days away. Plant in two week intervals. If we have an unusually warm September and October, greens can easily bolt before November. Planting in succession insures a crop throughout the winter.

Stepping Stones is arranged in most cases on a week to week basis within the months with gardening tasks described by order of the Seven Principles of Gardening, as needed, namely:
1. Plan and Design
2. Analyze and Improve the Soil
3. Create Practical Turf Areas
4, Choose Appropriate Plants
5. Efficient Use of Water
6. Use Organic or Inorganic Mulch
7. Practice Appropriate Maintenance

Following the weeks' tasks, I've included suggestions under the headings "Keep it Up",  "Extras", "Be a Plant Explorer" and "Oops! and/or Don't" -- extra tips I practice and have found to be important or interesting. If you've been gardening for several years, there will be fewer tasks each week for each principle. Included in the sidebar at the right are QuickSteps -- a summary or outline of tasks to do each month. Feel free to copy and print out to refer to during the month.

Don't worry if you can't get to the task in the first week suggested. These times are when I've noticed the earliest most likely success achievable. Naturally, each and every year will be different. Some years will be warmer, some cooler. Adjust and stay tuned to the weather.

Weeks One and Two

Plan and Design

When starting a new bed in a Bermudagrass or very weedy areas, now is the time to apply the second spraying of Roundup, or other glyphosate in hopes of killing Bermudagrass. The Bermudagrass and weeds need to be actively growing for the best kill. If it’s been dry, consider watering the area several days before spraying. However, this process is best started in August or even July. Normally I'm against the use of herbicides, however, the discriminate and limited use of them may be one's only option when ridding the area of such a pervasive plant.


The first half of September is a good time to re-seed, or seed, cool season fescue turf, or cool season turf blends.

It’ll be OK anytime in September and October to aerate and top dress the lawn with compost (insure the compost is free of persistent synthetic chemicals, see Maintenance, Composting, Killer Compost). I personally like to wait until the second half of September or October to top dress. Many people are attracted to the idea of a weed and feed product for their turf. A safe weed and feed to use is corn gluten meal. This will prevent the winter weeds from progressing immediately following germination. You may want to apply again after 3 weeks to prevent another crop of weed seeds from germinating. Corn gluten meal will not kill weeds that have already germinated and grown, nor will it kill plants that spread by rhizomes or stolons. It does not kill bindweed. Corn gluten meal is a good organic soil amendment. And again, if seeding or re-seeding a lawn, do not use corn gluten meal as an amendment until the grass seed is up and growing well.

Appropriate Plants

September is a good time to seed perennials and annual wildflowers for next year's blooms. Follow depth instructions for planting. Mark the seeded locations in some manner to avoid inadvertently disturbing them later. A rule of thumb I advise is to plant wildflower seeds at the time their seeds fall in nature.

Dig up and divide lilies or buy more at the annual daylily sale in September at Amarillo Botanical Gardens.

Fall Vegetables

Begin fall vegetable planting by seed or plant in earnest after the heat of summer breaks, normally around Labor Day.  Average date of the first frost is around October 20th.

  • At one to eight weeks before the average date of the first frost (ADFF), you can plant radishes.
  • 6 weeks before ADFF, plant garlic.
  • Lettuces, mache, spinach, kale, bok choy, broccoli raab, turnips, beets, onion sets can be planted now.

Consider succession planting lettuce to be harvested throughout winter.  Choose a winter growing variety from a seed catalog. I find it helpful to cover the lettuce bowl (bed) with a light row cover or frost blanket to shelter the seedlings from sun, wind and birds.  In warm falls, cool season greens can bolt before Thanksgiving. Succession planting will insure a late fall and winter harvest, right through the coldest months when using the poly tunnel system. Instructions for constructing the two cover tunnel system is at the end of February's Stepping Stones.


There is always a little tidying up of the garden to do, some deadheading, even some dividing and moving of spring blooming perennials. The fall bloomers should be blooming, so wait until they’ve finish for that.

Continue to harvest vegetables. Cut leaves of herbs for drying.

Collect seeds for next year's use, for trading and sharing with fellow gardeners.

Weeks Three and Four

Plan and Design

This late in the season, if a new bed area has Bermuda grass, you may want to rethink the timing and wait until next year to kill the Bermudagrass when it’s actively growing. Otherwise, working the soil in most other areas can be started from now until February.

Harvest or buy pumpkins, squash and gourds for display in the garden. Arrange little fall vignettes among asters, chrysanthemums, sedums and salvias.

Amend the Soil

For non-Bermuda grass areas, if using the smothering technique, or lasagna method of preparing a bed, do so now. Place a layer of 4-6 newspapers overlapping over the new bed area. Shovel coarse sand 1 – 3 inches deep, or other inorganic amendment (follow amendment instructions) on top for clay soil. Follow this with 3 inches of compost. Let this set until next year. Then work the soil with a garden fork, mixing in the material. Add another 3 inches or so of compost, depending on the type of plants chosen. Mix in again.

When I prepare a new bed using the lasagna method, I start in the fall, and work the soil and adding amendments after the top growth is killed a minimum of two times before planting, three is preferred. Preparing the ground properly is a very important factor in gardening success and quick establishment of plants. The chart on the  link recommends amounts of various amendments, per square feet.

Appropriate Plants

Begin to plant any new beds now. There is a short list of plants to avoid planting in the fall. High Country Gardens website has the list. These are mainly fall blooming perennials that need hotter days to establish. However, I called and talked with Santa Fe Greenhouse about this last year (2004). They said their caution on planting these heat-favoring plants was aimed mainly at Midwest and Northern gardeners where winter comes early, is wet, and stays long. HCG noted that, for our climate, as long as we provide proper drainage, they should winter over. If in doubt, however, plant in mid September for better success. I've planted many warm season plants in the fall, even in November that have overwintered some pretty cold winters. Proper soil drainage is the key.

When should one plant pansies, violas, kale, dianthus, snapdragons, ornamental cabbages, mums and asters, the traditional fall plants? After the summer heat has broken. Sometimes we don’t know when that is until the end of September, looking back. Mums asters, snapdragons and dianthus should be planted before pansies and violas, as pansies, violas, kale and cabbage prefer sunny, but cooler conditions. Care for them as needed until establishment. Winter annuals can also be planted in the large insulated foam containers that look like stoneware. The insulation allows them to winter over, most winters. They are high maintenance and need to be watered regularly and fed with “Pansy Food” for continued blooms throughout the winter months. If you seeded out ornamental kale and cabbage plants, they should be of a good size to plant outside.

A perennial ornamental herb that provides terrific foliage into the winter is Rumex sanguineus, red sorrel or red veined dock. Red sorrel can be cut back in September (and/or spring) to rejuvenate its appearance. Other ornamental vegetables to consider are ‘Bright Lights’, ‘Ruby Red’, and ‘Pink Passion’ Swiss chard, and ‘Red Giant’ mustard. Cut back bronze fennel to show new fall growth.

Monitor nighttime low temperatures. Protect tropicals from lows below 55º, and sub tropicals for temperatures below 40º.


Maintain the fall vegetable garden with timely irrigation and mulching. Benefits of a fall vegetable garden are fewer insect pests, fewer weeds and gradually cooler temperatures and less frequent watering. The fall vegetable harvest should be underway.


Along with the return of a new school year, formal gardening classes, workshops and seminars begin. Enroll in one. Southwestern states may offer xeriscape or water conservation conferences you may find useful and enlightening.

Organise a seed exchange to be held near the end of October.

Be a Plant Explorer

Grasses play a dominant roll in the flora of the Great Plains. Grasses native to the short grass prairie region predominate the Texas Panhandle region, with tiny pockets if mid and tall grasses scattered about in micro-niches. Tallgrasses in the Panhandle typically reach a height of 4 – 5 feet, their mature height depending on rainfall. This is small by Great Plains standards.

Less than 1% of tall grass prairie stands today. Several preserves within a day’s drive are the Konza Prairie and the Tallgrass Prairie National Preserve (photo at right taken in July) with the Flint Hills Preserves to the southeast of them. For those seeking the Lewis and Clark experience of breaking upon the ocean of grasses, these are good locations to embark on your journey. Together they comprise hundreds of acres of head high stands of big bluestem, Indian grass, switch grass, prairie cord grass, sunflowers and other forbs. View and study the prairie ecology of grasses, forbs, insects, mammals, birds, and butterflies. By October, green is replaced by golds and russets, and the biting insects are usually gone, as well. In 2004, Peterson Field Guide series released their newest guide: The North American Prairie, covering 18 states and provinces, including Texas. The prairie guide profiles 48 major prairie preserves and 120 smaller ones, including the best time to visit.

A different trip of the month is to the north or northeast for the fall foliage tour. It’s probably spectacular again this year. A shorter trip to the west will take you into the Rockies for viewing mountainsides of golden aspen color.

Keep it up

  • Mulch mow
  • Irrigate if necessary
  • Replenish mulch
  • Weed
  • Turn the compost pile and moisten if necessary
  • Update the gardening diary or journal
  • Keep visiting your gardening angel project.
  • Harvest vegetables, herbs and seeds.

Don’t or Oops!

  • Do wait until next May to seed or re-seed warm season turf grasses. September is too late.
  • Spring blooming bulbs have probably arrived in the mail by now. I wait until November to plant them, usually around Thanksgiving when I’m dying to do something outside.
  • Don’t perform fall clean up chores just yet, plants are still actively growing. But you can always tidy up the garden and deadhead to avoid flowers going to seed. Or leave the seeds of natives for birds to eat throughout the winter.
  • If your roses are the type that put on rose hips, don’t deadhead after the fall blooming. I’m not a rose specialist, but I’ve found it helpful to prune back the roses no later than the fifteenth of September if they are without buds.

Angie Hanna

Revised, February, 2018