Depending on what hardiness zone you live in, your garden is either starting to wind down for the year, or you're trying to pawn off that bumper crop of tomatoes or squash. One thing we all have in common is that in the coming weeks we'll need to take care of some basic garden maintenance so that our containers and beds will be ready to start anew come next spring.
1 Harvest what's left! For herbs, you can dry or freeze them, depending on variety. Berries? Turn them into preserves or freeze them whole to use later in pies or smoothies. Tomatoes? If they're green, you can pickle or can then. If they're ripe, make a big pot of sauce and can for later. Zucchini? Freeze them to make into zucchini bread in the dead of winter. I can smell it now!
2 Clean up! Empty pots, dump the soil in beds or put into your compost...the soil won't keep enough nutrients if stored for months. Stop fertilizing perennials (unless you live in a temperate zone), bring your garden ornaments and decor in for winter storage. Clean your garden tools before you put them away so they won't rust in storage.
3 Store it all away! Wash all your pots and allow them to sun dry before putting them away. It might sound weird, but it will kill any disease or viruses that could harm your future seedlings and plants, as well as help give any terracotta a longer life. To save space, you can store them nested.
Further reading: Home Made Simple - End-of-Summer Gardening Tasks