Pottering around: Now is the time to start sizing up herbs and other plants you may want to pot up before frost. If you have pots available and a clear idea which plants you’ll be saving, you can wait until frost is imminent before doing the deed. It’s not a bad time to plan for frost-free space indoors for your rescuees, together with whatever potted plants you’ve moved outside for the summer season.
Scrumptious squash: Pumpkins and winter squash taste best when left on the vine until after first frost — but there are exceptions to the rule, particularly in the South. Keep an eye on squash fruit and vines for insect damage. If vine borers have started in and the squash are fully formed, you may be better off harvesting a little early. Store them in a cool, shady place — frost may still improve the flavor even after harvest.
Divide and multiply: September is a fine time to divide peonies and other spring bloomers. Most perennials begin to crowd themselves after a few seasons, and by spreading them around you will boost bloom numbers and size. Specifics vary, but you can’t go too far wrong if you halve or quarter a clump of plants with a sharp shovel, taking a substantial clump of roots and replanting at the same depth. Always add soil amendments during this process, but be sure to use finished compost rather than putting fresh manure directly on the root ball.