Keep It Trimmed and Clean
A healthy height for grass blades is about 2 1/2 inches. Keep cutting your lawn during the fall as long as it keeps growing. Some people think they should let their lawns grow longer in anticipation of winter, but, in reality, mice and voles love the long grass under the snow. Many experts suggest you actually lower the blades on your mower to about 2″ to minimize potential problems.
Don’t let leaves pile up on your lawn, waiting until the trees are bare to rake them—a build up of leaves blocks out the sunlight grass blades need to stay healthy. A mower with a mulch setting or a bag attachment makes leaf clean up easier. If you prefer to use the old-fashioned rake method, remember that leaves make great mulches in gardens and also add valuable nutrients to a compost pile, so don’t just burn them, or throw them out.
Aerate Your Lawn
Aerating makes holes in your lawn that allow water and nutrients to get right down to the grass roots. You can rent an aerator at most home stores, and aerating your lawn won’t take any longer than cutting your lawn—so you only need to rent it for half a day. You could even make lawn aerating a group activity and team up with a few neighbors to share the cost of the rental.
Fall is a good time to add seed to your lawn so it grows thick and resists weeds, but don’t just grab the first lawn seed you see on sale at the home center. Different grass-seed mixtures are designed for different conditions, such as shade or direct sun.
Read the information on the bags or talk to a knowledgeable person at a garden center to get the right kind of grass seed for your lawn. (You may end up with a couple of different bags of seed but it’s a small price to pay for a good-looking lawn.)
When you’re applying the seed, use a rotary spreader, and apply the seed at the recommended rate. If your lawn is quite thin, you could even rent a ‘slicer seeder’ that actually cuts small grooves in the soil, into which the seeds fall. After seeding, give your lawn a good watering so the seeds can get off to a good start.
Fall is the key time to fertilize your lawn. Applying a good fertilizer in late fall (around Halloween, or later in warmer parts of the country) will give your lawn a real pre-winter boost and get it ready for the upcoming cold. You could take a soil sample and have it tested to determine the exact nutrients your lawn needs, but most commercially-available, bagged fertilizers do a more than adequate job.
Fertilizers contain three nutrients (nitrogen, phosphorus, and potassium) and they’re listed on the bags in their relative proportions. For example a 25-3-10 fertilizer contains 25% nitrogen, 3% phosphorus, and 10% potassium. In a good fall fertilizer, the first number (nitrogen) is about twice the last number (potassium). The nitrogen helps build strong, healthy roots, while the potassium helps your lawn survive the cold.
It should go without saying, but if you’ve just seeded your lawn, don’t apply a fertilizer that contains a weed-killer ingredient.