What Zone Are You In? -- In all but the coldest regions (Zones 5 and colder), early fall is an excellent time to plant perennials, container trees and shrubs, and roses. This month, however, it can still be hot. Do the planting on a cool, overcast, or rainy day to prevent heat stress.
Watering -- September can be the driest month of the year. Remember the basics: Water in the early morning. Water the soil, not the leaves. Water deeply and occasionally rather than shallow and often.
Drought Survival for Your Lawn -- Check out our lawn drought-survival tips.
Repair the Lawn -- In cooler regions, September is also an excellent month to reseed and repair lawns. You'll need to water as often as daily until the seed has sprouted and established.
Whack Your Weeds -- Although this time of year it's tempting to forget about weeding, keep up with it. There's an old saying about weeds that one year's seeding means seven years' weeding.
Deadheading 101 -- Even now, keep deadheading! You'll have more flowers longer, not to mention a nicer-looking garden.
First Frost -- In Zones 3 and colder and at high elevations, your first frost is likely to come this month. Stay tuned to the television and newspaper forecasts to find out exactly when. Prolong the growing season by throwing a sheet or other non-plastic material over your annuals and vegetables. In fact, for vegetables, you can cover them indefinitely with any very light landscape fabric and anchor the corners with bricks or stones. It lets in sun and rain, but prevents light frosts from doing any damage.
Bird Feeding -- Fall is the time overwintering birds establish their food sources. If you haven't already, put out your bird feeding equipment.