Fall is the best time of year to do most all lawn maintenance. In the fall, rains return and cooler temperatures allow lawns to begin to build themselves back up from the harsh summer heat. In the winter, the lawn can become dormant and then be fully healthy when spring returns.
Grub Control and Pest Checks
Grub worms such as the Japanese beetle or masked chafer adults are potentially one of the worst pests for turf grass. They burrow into the turf, lay dozens of eggs and then go to town on the grass roots. Unfortunately, this happens in late summer and early fall, but the damage might not be seen until long after winter and into the spring. It is best to apply an insecticide to the lawn each year to prevent widespread and costly damage. Dylox and Sevin are harsh chemicals which will kill grubs if you know your lawn is infested. For preventative maintenance, use an organic compound such as nematodes (Heterorhabditis spp.).
Leaves should be removed once a week in order to allow the grass the ideal amount of sunlight. With hindered sunlight the lawn cannot store enough energy to make it through the winter dormancy in a healthy state. Don't blow the leaves away, but rather rake them and create a compost pile. Once the leaves disintegrate, they are ideal to be mixed with an organic fertilizer and sprinkled across the lawn. By allowing them to fall apart, the nutrients of the leaves are not in tiny pieces which will not block the sun.
Organic Based Fertilizer
Organic fertilizers allow for slow release of the nitrogen compounds so the lawn will not become burned or turn brown in places. The slow release also helps to prevent run-off and minimizes the number of applications needed. Organic fertilizers also contain important iron compounds to help the lawn as well. Synthetic iron fertilizers must be used very carefully because if over applied the lawn will turn blue and damage can be hard to reverse. Milorganite is one of the best products out there, but must be used in the heat rather than late fall or early spring.
Liquid Weed Control
Blanket weed controls like Weed and Feed cause serious damage to the water supply and usually are not as effective. Always use a liquid weed killer and spray problem areas. By targeting weeds where they are and no where else, you are not harming the microfungi in the soils which are beneficial. If you take the time to do it right the first few times, the issue will become simple and easily manageable. Be sure any and all weed killer which is applied reads "Safe for Lawns" or you might have a much larger problem on your hands than a few weeds. Generalized weed killers like Round-Up will not be safe on lawns because they kill anything and everything. You want specific weed killer such as a "broad leaf herbicide." Often weed killer might need a couple applications in cooler weather. Higher concentrations will not yield better results.