Lightly Prune Roses
You can continue to cut rose flowers to take indoors for the next week or two, but by early October it's best to leave faded roses on the bush and allow them to form hips. The hips signal the plant to prepare for cold weather, helping to ease it into dormancy. A plant properly hardened off in fall will survive our winters much better.
Sow Cover Crops
As the vegetable garden completes its cycle, pull out and compost disease-free plants. This will leave room to sow the seeds of a cover crop to help fix nitrogen and prevent soil erosion through the winter. Hairy vetch and Austrian peas are good nitrogen-fixing cover crops, while winter rye is a good general cover crop for our region.
Coax Poinsettias into Bloom
Late September is the time to bring poinsettia plants indoors and condition them to bloom by providing total darkness for about 16 hours each day. The method I prefer is to set the plant in a bright room for 8 hours, and then either put a box over it or put it in a closet for 16 hours. In early December, once the leaf bracts begin to show color, stop the conditioning process and leave the plant in a bright location.
Remove Fall Webworms
Larvae of the Hyphantria moth construct webbed tents around branches in the tops of trees and shrubs such as apple, ash, and plum during the late summer and fall months. These pests will defoliate, but they won't kill a healthy tree or shrub. Destroy colonies by breaking open the webs with a broom handle and letting natural predators find and eradicate them.
Clean up leaves and debris, mow, and otherwise tidy the lawn. Dig out clumps of weedy grass and rake out dead spots. To reseed dead spots, scratch the soil surface with an iron rake to loosen the soil, lightly scatter seed over the bare area, top-dress it lightly with compost, and water well. Cooler fall temperatures and natural rainfall will help the grass green up in a hurry.