September Gardening Guide
- Hannah O'Connor
- 2 hours ago
- 5 min read
September in Central Texas marks the shift from the intense summer heat to the start of the fall gardening season. With cooler nights and shorter days ahead, it’s the perfect time to reset your garden, refresh your soil, and prepare for new plantings. From vegetables to lawns, flowers to trees, September tasks lay the foundation for success in the months to come. By tackling a few key chores now, you’ll enjoy a healthier and more productive garden this fall and beyond.
Watering
As September progresses, it’s important to rethink your watering routine. Plants don’t need as much water as they did in the heat of summer, so reducing irrigation not only conserves resources but also keeps lawns and beds healthier. Overwatering this time of year can encourage fungal issues like Brown Patch in turf, while underwatering can stress new transplants.
Adjust schedules: Shorter days and cooler nights mean less evaporation. Begin dialing back your irrigation timer to match the season.
Deep and infrequent: Focus on thoroughly soaking the soil, but do so less often. This practice encourages deep roots, making plants more resilient as conditions shift.
Vegetable beds: For seedlings and young transplants, keep soil evenly moist but not soggy. A quick check with your finger a couple of inches down is the best way to gauge whether it’s time to water again.
This balance between reducing excess moisture and keeping new plantings supported will help your garden thrive into fall.
Fertilize
Fertilizing in September is all about setting your plants up for strong root development and steady growth through fall. Unlike spring, when the focus is often on pushing out lush foliage and blooms, autumn is the season to build a solid foundation underground.
Vegetables: Cool-season crops like broccoli, spinach, and kale benefit from regular feeding. Apply a balanced, water-soluble fertilizer such as fish emulsion every two weeks to give them the nutrients they need for steady growth.
Lawns: This is one of the most important times to fertilize your lawn. Use an organic fall blend designed to strengthen roots and improve soil health. Products like MicroLife 6-2-4 paired with Humates Plus build beneficial microbes in the soil while supporting turfgrass as it prepares for dormancy.
Garden Beds: Before planting fall flowers or vegetables, top-dress beds with compost or aged manure. Improving the entire bed—rather than just the planting hole—encourages roots to spread evenly and makes plants more resilient over time.
By fertilizing wisely this month, you’ll give your garden the strength it needs to flourish through cooler weather and into the next growing season.
Planting
September is one of the most exciting planting months in Central Texas. As the summer heat starts to fade, the soil is still warm enough to encourage fast root growth, making it the perfect time to establish cool-season vegetables, flowers, and even new trees and shrubs.
Vegetables: Direct sow beets, carrots, radishes, turnips, spinach, and collards. These cool-weather crops thrive when started from seed right now. For a quicker harvest, you can also set out transplants of broccoli, cauliflower, and cabbage.
Wildflowers: Early fall is the prime time to scatter seeds for Texas wildflowers like bluebonnets and Indian blanket. Planting now ensures they germinate in the fall, grow strong roots through winter, and burst into bloom next spring.
Trees & Shrubs: Take advantage of the mild weather by planting new trees, shrubs, and perennials. Roots establish more effectively in cooler temperatures, giving plants a head start before next summer’s heat.
By choosing the right plants and getting them in the ground this month, you’re setting up your garden for both immediate beauty and long-term success.
Lawns
September is a turning point for Central Texas lawns. Grass growth begins to slow, but the roots are still active, making this the best time to focus on strengthening turf for winter. Paying attention now will help your lawn stay green longer, resist disease, and come back stronger in spring.
Fertilize wisely: Apply a fall fertilizer to encourage root growth rather than lush top growth. Organic blends, such as MicroLife 6-2-4 paired with Humates Plus, build healthy soil while preparing turf for dormancy.
Disease prevention: Cooler nights and high humidity can trigger fungal problems like Brown Patch and Take-All Root Rot. Reduce watering frequency, avoid evening irrigation, and keep lawns well-aerated to prevent these diseases from taking hold.
Weed control: Tackle weeds before they spread. Hand-pull or mow young weeds, and consider applying a pre-emergent herbicide in mid-September to block winter annual weeds from germinating.
Leaf management: As trees begin to shed, mulch fallen leaves back into the turf with your mower. This returns nutrients to the soil and reduces the need for added fertilizer later.
With these steps, your lawn will transition smoothly into the cooler months and return healthier when spring arrives.
Pests & Diseases to Watch
Early fall often brings a new wave of garden challenges. As summer's heat stress fades, cooler nights and increased moisture can create ideal conditions for pests and fungal problems. Staying vigilant in September helps you catch issues early before they spread.
Caterpillars: Armyworms, cutworms, and other leaf-chewing caterpillars tend to surge this month. Check vegetables and ornamentals for chewed foliage and frass (droppings). Handpick smaller infestations or treat with Bacillus thuringiensis (Bt) for a safe, targeted solution.
Ornamental diseases: Roses and other landscape plants may show signs of fungal leaf spot or mildew. Promptly remove infected leaves and debris to slow the spread of disease.
Lawn diseases: Brown Patch and Take-All Root Rot are common in St. Augustine and Zoysia this time of year. Watch for yellowing patches or turf that pulls up easily. Avoid overwatering, improve soil drainage, and top-dress with compost or peat moss to help suppress fungal activity.
A little prevention goes a long way. By keeping an eye out for these seasonal pests and diseases, you can protect your fall plantings and maintain a healthier garden overall.
Maintenance
September is also the month to refresh and reset your garden spaces. Summer’s heat and storms may have left things looking tired, but a little cleanup now will make room for fall color and healthier growth.
Mulch and compost: Add a fresh layer of mulch around perennials, shrubs, and trees to conserve soil moisture and regulate temperature. Turning compost piles during mild weather also helps speed decomposition.
Seasonal cleanup: Cut back worn-out summer annuals to clear space for fall flowers like pansies, dianthus, and snapdragons. Remove any dead or damaged growth from shrubs and perennials to reduce stress on plants.
Garden prep: Prepare vegetable beds by loosening the soil, mixing in compost, and planning your next succession of plantings. For ornamental beds, this is a good time to restock with perennials or divide clumping plants that have outgrown their space.
Tools and gear: Take advantage of cooler mornings to tidy the shed, sharpen pruners, and oil any rusty tools. Having everything in good shape makes the busy fall planting season easier to manage.
With a bit of maintenance now, your garden will be refreshed, organized, and ready to shine in the months ahead.
Conclusion
September is a month of opportunity for Central Texas gardeners. Cooler nights and shorter days create the perfect conditions to plant cool-season vegetables, establish wildflowers, and give your lawn and landscape a boost before winter. By fertilizing wisely, adjusting watering routines, and staying alert to pests and diseases, you can set your garden up for success well into the fall and beyond. A little effort now pays off in healthier plants, vibrant landscapes, and a more enjoyable season outdoors.
Sources
Texas A&M AgriLife Extension. Monthly Gardening Checklist for Austin and Central Texas
Texas A&M AgriLife Extension. Vegetable Planting Guide for Williamson County
City of Austin & Texas AgriLife Extension. Grow Green Native and Adapted Plant Guide
City of Austin & Texas AgriLife Extension. Grow Green Guides – Weeds and Lawn Care
MicroLife Fertilizer. Guide to Fall Plant Success
Texas A&M AgriLife Extension. Turfgrass Diseases: Brown Patch and Take-All Root Rot
Howard, Doreen G. “Know Your Dirt: Soil Types and Garden Success.” Farmer’s Almanac