First of all, it's best to remember that peonies really don't respond well to transplanting. They'll grow quite well in the same place for fifty years. That said, if you have peonies that are in the wrong spot or if you want to increase the number of peonies in your garden inexpensively, then late August through September is the time to divide or transplant them. Dig as large of a rootball as possible. Replant so that the "eyes," or growing points, are only buried an inch or two beneath the soil surface.
Begin Repotting Houseplants
Houseplants, especially ones that have summered outdoors, tend to put on a growth spurt during the summer, so it's a good idea to check for which ones need repotting into a bigger container. It's a lot easier to do outside where the mess won't be much of a problem. Choose a pot that is only an inch or two larger than previously and a high-quality potting mix. Be sure to moisten the soil mix before potting up.
Check Your Rain Gauge
September and October can be among the driest months of the year, so it's a good idea to get in the habit of checking your rain gauge at least once a week. Trees and shrubs that were planted this year are especially sensitive to droughts. Be sure that the area around them is weed-free and mulched well to help maintain even soil moisture. If there hasn't been any rain for a week and none is predicted, slowly soak the soil around these plantings.
Bring the glorious flavor of summer's basil to winter meals by making and freezing pesto now when fresh basil is in abundance, either in your own garden or at a farmer's market. To make, lightly toast one-third cup pine nuts, walnuts, or almonds, cool, and place in a food processor and pulse two or three times. Add 2 cups firmly packed fresh basil and pulse a few more times. Add 1 tablespoon lemon juice and pulse. Slowly add one-half cup extra-virgin olive oil while the processor is running. Freeze in containers. To use, thaw and add a bit of chopped fresh garlic and freshly grated Parmesan cheese.
Don't be tempted to continue feeding trees, shrubs, and roses any more this season. The fertilizer encourages new growth, which won't have time to mature before freezing weather. Plants are now in the hardening-off phase of their growth cycle, preparing for winter.