Divide or Move Daylilies
Older varieties of daylilies can usually go for many years without needing division, but newer hybrids perform best when divided every 4-5 years. Repeat blooming daylilies will put on the best show when divided even more frequently, every 2-3 years. Use two spading forks back to back to pry apart the crowns of daylily plants.
Fertilize Lawns in Early Fall
The best time to fertilize the cool season lawn grasses we grow in our region is in early fall. To both benefit turf the most and reduce the likelihood of fertilizer runoff polluting nearby waterways, put down fertilizer by September 15 in northern parts of New England and by October 15 in southern parts. Don't put down more than one pound of actual nitrogen per 1000 square feet in one application. Choose a fertilizer with at least 50% of its nitrogen in slow-release or water-insoluble form and without phosphorus unless a soil test indicates a soil deficiency.
Sow Grass Seed
Now is a good time to sow seed for a new lawn, to fill in bare spots, or to overseed a lawn that is thin. Grass seed germinates readily in warm soil and the young plants will continue to grow well in the cooler, wetter fall weather after frost has killed off the annual weeds that are competing with them. Wait until September to fertilize established lawns.
Let Herbs Go to Seed
Let your last planting of annual herbs such as dill, cilantro, caraway, and chervil go to seed. The flowers will attract beneficial insects and the seeds that fall to the ground will self-sow, giving you a new crop of plants to harvest from early next season.
Sow Cover Crops as Garden Beds Empty
As summer crops finish bearing and space in beds begins to open up, sow a cover crop to help protect soil over the winter and add organic matter. Annual rye and oats are good choices that usually die over the winter in our region. The killed tops provide winter soil cover and the roots and tops add organic matter to the soil. You don't need to turn them under to kill them in the spring and wait for them to decompose before spring planting, as you do with hardier cover crops like winter rye that survive the winter.