September Planting Guide Start leafy crops early in the month to give them time to mature before hard frosts arrive. Use row covers to protect tender seedlings if temperatures drop suddenly. Divide and transplant perennials now so roots establish before winter. Space cool-season vegetables closely to shade soil and suppress weeds naturally. Mulch around new succulents to prevent sudden cold damage and retain warmth. Water consistently but reduce frequency as growth slows in cooler weather. Choose annuals labeled frost-tolerant to extend color late into the season.