September Garden Guide - A Maintenance Checklist for South Louisiana

September in Baton Rouge is a true transition month. Nights start to cool a bit, but daytime heat and warm soil are still the reality. This is a great window to squeeze in a fall tomato crop (heat-set varieties) while beginning the shift toward cool-season vegetables. Many cool crops can go in now, but starting seeds for transplanting in October (or waiting until mid-to-late September for some transplants) often works better in our still-hot soils.

Flower Beds & Landscape

Keep summer color going while preparing for the change.

• Continue with heat-tolerant annuals such as portulaca, angelonia, coleus, and marigolds
• Deadhead and tidy up leggy plants
• Refresh mulch to keep roots cooler and retain moisture
• Pull summer weeds before they drop seed
• Begin watching for cool-season annuals (pansies, violas) that will become more available later in the month or in October

Vegetables – What to Plant in September (Baton Rouge)

(Use the full Louisiana Vegetable Planting Guide on the LSU AgCenter website for spacing, depth, and variety recommendations.)

• Fall tomatoes: Yes, you can still plant heat-set varieties (Florida 91, Phoenix, Solar Fire, Heatwave, etc.) early in the month for an October–November harvest. Get them in as soon as possible.
• Continue or plant peppers, eggplant, bush snap beans (early September), and other warm-season crops that still have time.
• Cool-season crops: Start seeds now of broccoli, cabbage, cauliflower, Brussels sprouts, kale, collards, lettuce, and Swiss chard for transplanting in October when soil temperatures moderate.
  Direct-seed more heat-tolerant options now or mid-month: collards, mustard, turnip greens, beets, carrots, radishes, and English/snow peas.
• Shallot sets and Irish potato pieces (small whole potatoes) can go in.
• Garlic can be planted mid-to-late September.

It’s a tad early for some head brassicas to go straight into warm soil, so seeding for later transplanting is often the smarter move in Baton Rouge.

Trees, Shrubs & Vines

• Prune everblooming roses (hybrid teas, shrub roses, etc.) by about one-third in early September to set them up for a strong fall bloom
• Lightly shape non-flowering hedges if needed
• Plant container-grown trees and shrubs while the soil is warm
• Water new plantings consistently

Bulbs & Perennials

• Deadhead summer perennials and tropicals
• Continue enjoying cannas, elephant ears, and gingers
• Hold off on most spring-flowering bulbs until October–November

Lawn Care

• Stop or greatly reduce high-nitrogen fertilizer after early September
• Keep mowing at the proper height with sharp blades
• Apply a pre-emergent herbicide in late September to prevent winter weeds (henbit, chickweed, annual bluegrass)
• Watch for late-season armyworms or sod webworms
• Water deeply when needed between rains

Watering & Irrigation

• New vegetable plantings and tomato transplants need consistent moisture — September heat can still dry soil quickly
• Water early in the morning
• Mulch helps a lot with both new and established plants

Pests & Diseases

• Stay on top of residual summer pests (stink bugs, whiteflies, caterpillars)
• Monitor tomatoes and peppers closely
• Watch for fungal issues in humid stretches
• Remove spent or heavily diseased summer crops to reduce pressure on new plantings

General Garden Tasks

• Clear out finished summer vegetables to make room
• Add compost to beds before new plantings
• Start seeds of cool-season crops in trays or pots for October transplanting
• Keep tools clean and beds mulched

Final Thoughts

In Baton Rouge, September lets you play both sides of the season. Get those fall tomatoes in early while the weather still supports them, start cool-season seeds for next month’s transplants, and begin direct-seeding the tougher greens and root crops. Nights are easing, but the soil is still warm, work with that rather than fighting it.

Stay consistent with watering and pest checks, and you’ll set yourself up for a strong fall harvest that can stretch well into the cooler months. Get outside and enjoy the shift.