Seeds spread after October 15 grow less vigorously because they receive less light and have cooler soil and air temperatures. It's certainly possible to seed a lawn after October 15, but optimal conditions occur earlier. Plan your hardy bulb plantings. Tulips, narcissus, hyacinths, crocus, and other hardy bulbs for fall planting arrive in nurseries after Labor Day. Plant anytime between October 1 and December 1, but plan to water if the soil is dry when bulbs go in.
Bulbs establish best with cool, damp soil.
Root growth is vital for all spring-blooming bulbs during fall, and the bulbs won't grow without receptive, moistened soil to sink roots into. Larger, later-blooming bulbs can wait for planting in late October or even into November. The ideal is to get all these bulbs into the ground by about November 15, though gardeners have been known to do it successfully in December. This is a frequent question, and fall's a good time to consider a soil test. Soil tests make sense for those planning vegetable gardens on land not previously planted to vegetables.