While many homeowners think of fall as the end of the gardening year and begin to neglect their yards, lawn pros and organic gardeners see the fall as the beginning of lawn season, and do what they can to improve the lawn and soil quality at this time.
In the fall, lawns have the opportunity to rebuild, repair and thicken up after going through the stresses of summer. The lawn attempts to expand its root system at this time, digging in and getting to more of the soil nutrients. It also increases blade growth, making more carbohydrates (food) and some of this food is stored for spring and summer use.
In the fall, conditions are usually more favorable for seeding, too. The weather should be cooler and moister, and there will be less weed and disease pressure to contend with.
Early Fall Fertilizing: In our lawn service business, we save our heaviest fertilizing of the year for the early fall. This stimulates growth and helps the grass send out tillers and runners to fill in thin spots. It also helps the grass produce the food that it stores to help it through the winter and gets it off to a good start in the spring.
Soil Improvement: Clay and soil compaction can prevent your lawn from being healthy even when you are doing everything else right. With a porous, bioactive soil, the grass roots can become fuller and can go deeper. When the soil has better structure, the naturally occurring soil nutrients, as well as the nutrients from your fertilizers, become more easily available to the grass and other plants in your yard.
Our company uses a liquid soil conditioner called Aerify PLUS to help aerate and bio activate soils, and to provide some readily available organic matter. (As a matter of disclosure, we developed and sell this product on-line). Other traditional methods of soil improvement we recommend are compost top-dressing, lime (if soils test acidic) and granular organic fertilizers.
Aeration: Our company stopped doing core aerations about 10 years ago. We felt we could do a lot more for the soil and grass by doing "liquid aerations" instead. We use the same Aerify PLUS for our liquid aerations. If you would like to read more on this, click on this link: Notes on Core Aeration.
Thatch: Thatch is not just old grass clippings sitting on top of the lawn. Real thatch is a tightly matted barrier that could not be raked off without tearing up the lawn.
We believe the best way to get rid of thatch is to get it to decompose from the soil line upwards. The soil temperatures are warm enough through much of the fall for decomposition. But decomposition doesn't happen unless you have an aerated and bioactive soil (see above). Read more about this and biological dethatching in the post on our website called All About Thatch.
Seeding/Renovation: There are many reasons to overseed your lawn. Aside from thickening it up, you can introduce newer, more heat-, insect- and disease-tolerant grass types. If your lawn is thin or has poor color grasses, you could use some renovation. Get new grass seed established in the early fall and it will thicken further in the spring. Seed any bare or thin areas now and up until early October.
A simple overseed, if your lawn does not have a thatch barrier, can be done this way: Spread seed over the existing grass, water heavily to work the seed down to the soil. Then keep the soil damp for a few weeks. A lot of this seed will take hold, especially if you spray Aerify PLUS right after seeding.
If you want to do a professional quality overseed, try to find a place that rents slit-seeding machines (sometimes called lawn renovators). This machine cuts grooves into the soil about 1½ inches apart and drops the seed into them. You get better soil/seed contact and a higher germination rate. Apply a starter fertilizer when seeding, or use our 10-8-8.
Mowing: Keep the grass fairly high into the early fall (unless your lawn is mostly bentgrass, which needs to be cut shorter). This will help the grass root deeper, thicken up and build up food reserves. Don't start mowing short just because the weather turns cooler. Lawn season is not over yet!
When the lawn's growth begins to slow down, that is your signal to begin mowing shorter. Gradually lower the mowing height so it is 1½ inches high or less before winter. Bentgrass lawns can be cut even shorter. Also, be sure to keep leaves from matting up on the lawn.
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