Disconnect and Store Hoses
Even if you have frost-free outdoor spigots, it's important to disconnect hoses from them in freezing weather to avoid damage. It's a good idea to shut off water to all outdoor spigots before cold weather sets in. Drain and store hoses out of the weather.
Cut Back Some, Not All Perennials
While you can wait until spring to cut back the tops of perennial flowers, it's nice to get some of this chore out of the way in fall after a hard frost. The foliage of plants like daylilies is usually pretty scruffy looking by late fall, so I cut these back now. Also I've found that the leaves of Siberian irises are much easier to cut back in fall when they are still fairly crisp. Cutting them off when they are a soggy mass in spring is much more of a chore. Some perennials like Shasta daisies, Jacob's ladder, salvias, and Oriental poppies put out a new clump of leaves at their base when they finish blooming. Leave this basal foliage clump untouched for the winter. Other perennials that shouldn't be cut back in fall include heucheras, sea thrift (Armeria), hellebore, pinks (Dianthus), and rock cress (Arabis). And some perennials like purple coneflower and rudbeckia and ornamental grasses can be left standing for winter interest and to feed the birds.
Mulch Root Crops to Extend Your Harvest
Throw about a foot of hay over your unharvested root crops before the ground freezes. This will insulate the soil and you'll be able to go out in late fall and early winter, pull back the hay, and continue your harvest of carrots, beets, and parsnips. Extend the mulch out about a foot and a half on each side of the planting.
Replenish your Soil
Fall is a great time to add slow-acting amendments to the soil. Do a soil test first, then add lime and rock powders like rock phosphate and greensand if needed. Now is also a good time to replenish the soil by adding compost, chopped leaves, or other organic matter.
Get Your Christmas Cactus Ready for Bloom
Christmas cacti need some special treatment at this time of the year in order to be ready to bloom this winter. Give your plant six to eight weeks of uninterrupted darkness every night beginning in mid-October in order to have it in bloom for the holidays. Place your plant in a closet or unused room where it won't accidentally get illuminated. Once you see buds forming, you can stop this treatment. Just don't forget to move the plant back into the light each morning! Christmas cacti also set flower buds if given a cold treatment instead. Beginning in early November, give them 50 to 55 degree F temperatures until you see buds form. You can give them a cold treatment by leaving plants that summered outdoors outside until just before frost, but they may begin to bloom before the holiday season.