September is the best time to tend to lawns. Aerate, compost, feed and over-seed existing lawns and seed new ones. If you only fertilize once/year, now is the ideal time.
Divide and transplant spring-blooming perennials.
Start cleaning up for fall by removing weeds and dead annuals.
Plant trees and shrubs now into the fall. Be sure to check the root balls and remove and/or straighten circling roots.
Take note of the plants in your garden. Do you wish you had more early fall interest?
Some favorite reliable perennials that put on a show in September include Anemone, Aster, Actea, Ceratostigma, Phlox, & Sedum.
Many ornamental grasses have showy seed-heads and colorful foliage starting now.
Franklinia and Heptacodium are wonderful September-blooming trees, and tough Clematis paniculata covers its support with fragrant white blossoms.
In the Edible Garden:
Share, preserve and enjoy the abundant harvest.
Freeze tomatoes whole in air-tight containers if you don't have the time to cook them down first.
Pickles are a fun, fast and easy way to preserve cucumbers, and can be canned or frozen for a mid-winter reminder of summer. Use the freshest, best quality produce for preserving.
Harvest apples as they ripen. Different varieties mature at different times. You can tell when apples are ready to pick if they show good color and separate easily from the tree. Promptly use any that are bruised or damaged.
Remove dropped fruits to reduce future insect and disease problems.
Sow spinach for a fall crop before the middle of the month.
By the end of the month, winter squash will be ready for harvesting. Leaving a portion of the stem attached will prevent rot of stored squash.
Sort out the best large, firm, and blemish-free garlic bulbs for re-planting in October. The rest can be stored in a cool, dry location and enjoyed through the winter.