With fall just around the corner, September is a great time to prepare your garden for cooler weather using these monthly tasks:
Lawn
- Do not apply any more nitrogen fertilizer to warm-season lawns as they naturally slow down growth before winter.
- If your soil test report showed low potassium levels, apply a high-potassium fertilizer such as 0-0-50 at 2 lbs. per 1,000 sq. ft. by mid-September.
- Treat lawns that suffered from large patch disease in the spring with a fungicide this fall.
- Reduce your irrigation frequency this month as days become shorter and cooler.
- Apply a pre-emergent herbicide in September to prevent winter weeds from taking over your lawns.
Trees, Shrubs, and Flowers
- September is an ideal time to divide and transplant spring-blooming perennials.
- Plant pansies and other winter annuals from mid-September through mid-October to help them establish before the first frost.
- Avoid major pruning in the fall, as it depletes energy reserves needed for spring growth, and only remove dead, dying, or diseased branches.
- Skip heavy fertilizer applications on trees and shrubs because tender new growth can be easily damaged when colder weather arrives.
- Trigger reblooming on last year’s poinsettia by placing it in total, uninterrupted darkness for 15 hours a day starting the last week of September, making sure it receives bright sunlight during the day.
- Inspect houseplants for insects and repot any root-bound plants before bringing them back inside for the winter.
- Save seeds from self-pollinating annuals like marigolds and zinnias by letting flower heads mature, drying them on newspaper, and storing them in paper envelopes or glass jars in a cool, dark place.
- If dry autumn weather sets in around October, water young or recently planted trees and shrubs.
- Remember that fungal leaf spots are common on trees and shrubs in fall and rarely require chemical treatment.
Fruit, Vegetables, and Herbs
- Set out transplants for broccoli, cabbage, collards, kale, spinach, and Swiss chard in early September.
