As temperatures start to abate at higher elevations, reinvigorate overcrowded daylily and hosta perennials as needed, usually every three to five years. Dig and divide by pulling apart clumps or cutting through roots with a sharp, sterile knife. Never let roots dry out. Replant immediately and spread several inches of mulch around plants.
Clean Up Pest Problems
If vining vegetables had pest problems, such as squash beetles or borers, rake and dispose of leaf litter to prevent eggs and larvae from over-wintering in the garden.
Improve Garden Soil
Prepare garden beds for cool-season planting. Amend soil with 4 to 6 inches of compost or other organic matter. Plentiful organic matter attracts earthworms that help build better soil. Add a source of nitrogen and phosphorus. Organic nitrogen choices include alfalfa meal, blood meal, coffee grounds, fish emulsion, and guano. Organic phosphorus sources are bone meal and rock phosphate. Dig in to a depth of 12 to 18 inches and rake smooth.
Prepare Lawns for Overseeding
If you overseed your warm-season Bermuda lawn with cool-season ryegrass in October, stop fertilizing four to six weeks in advance. If you do not overseed, continue regular monthly feeding in September and October.
Finish Transplanting Palms
September is the last month to transplant palms in the low desert while temperatures are still warm to help roots establish.