Previous coverage This is Part 2 on how to create a low-maintenance lawn that also is friendly to the environment. Part I:Keep your lawn lush with proper feeding, cutting and watering

Fertilizing

To determine the best way to fertilize for optimal health and growth of your lawn, perform a soil test. Inadequate or excessive treatment can limit turf growth and/or make it more susceptible to insect and disease problems. For example, an over-fertilized lawn is more susceptible to attack by insects that feed with piercing-sucking mouthparts, such as chinch bugs.

Be sure to use fertilizers that contain at least 30 percent of water-insoluble nitrogen (WIN) that provide an even level of nutrients for your lawn for eight to 12 weeks, instead of cheaper, fast-release fertilizers such as ammonium nitrate or ammonium sulfate. Quick-release solutions have an acidifying effect on the soil and do nothing to stimulate microbial activity in the soil.

It will also tell you what you have to do to get your soil pH (acidity or alkalinity) into the optimum range of 6.5 to 7.0 that most turfgrasses prefer. Soil test kits are available from your local Penn State Extension office for a nominal fee.

In Allegheny County, consumer soil test kits cost $12 each, and come with detailed instructions. Customers ordering multiple kits at one time pay $9 each for the additional kits. Send a check made payable to:

Penn State Extension
400 N. Lexington St.
Pittsburgh, PA 15208.
Write "Attn. Soil Test Kit" in the lower left corner of the envelope.

Typically, late spring (mid- to late May), late summer (late August to mid-September) and late fall (mid-November) are the best times to apply fertilizer.

Liming is best done in fall. Limestone moves through the soil very slowly and takes time to effect the desired change in pH. If your soil test reveals that your lawn needs 100 pounds or more of limestone per thousand square feet, break it into two applications, half in the fall and half the following spring.

Thatch

You should also check your lawn for thatch, the layer of organic matter between the soil surface and the crowns of the grass plants that forms as grass plants slough off dead leaves, stems and roots. Dig up a small square of turf to examine the soil profile. A thin layer of thatch --  1/2 inch or less -- is desirable. It acts as a mulch, moderating soil temperature and maintaining soil moisture.

More than that creates problems, though. A thick layer of thatch can keep water from reaching the soil and that creates more thatch as roots die when they dry out completely. Thatch is a breeding ground for insect and disease problems.

Even worse, if your lawn does develop a problem with white grubs (soil dwelling-insects that feed on turf roots), a thick thatch layer can make it very difficult to get an insecticide down to where the grubs are feeding.

The causes of thatch include the variety of grasses in your lawn. Bluegrass and creeping red fescue are the worst thatch formers of the cool season grasses. If your soil pH is lower than 6.5, the microbes that live in the soil and break down thatch are unable to function. If you overfertilize your lawn or if you water shallowly and infrequently, you encourage thatch buildup.

Allowing your grass to grow too long, then cutting it too short and letting the long grass lie on the lawn also contributes to thatch buildup. If you stick to rule to cut a third of the grass blade each time or use a mulching mower, the grass clippings are small and break down quickly, and do not cause thatch to build up.

A moderate layer of thatch -- between  1/2 and 1 inch -- can be removed by dethatching your lawn with a power dethatcher. This practice, however, is very stressful and should only be done in fall. You can rent dethatchers, or hire a lawn service to do it for you. Run the dethatcher in one direction, and then go over your lawn in the perpendicular direction. To help the lawn recover, overseed with varieties of turfgrass that match your lawn.

Aerating

If you do not have a thatch problem, but the soil is compacted, rent a core aerator. Again, they are available from many tool rental shops, or you can hire a lawn service to aerate for you.

Core aerators pull 3- to 4-inch plugs of soil out of the ground and leave small holes behind. Fall is ideal for core aeration, but it can be done in the spring as well. If your lawn does not have a lot of activity on it, core aeration every three years or so will keep the soil aerated sufficiently. If all the neighborhood kids play in your yard, consider yearly core aeration in late fall to keep soil compaction to a minimum.

It is good to leave the cores on the soil surface, where they will break down during winter's freeze-thaw cycles. If the cores create a muddy mess rake them up and put them on the compost pile. You can also leave them on the lawn and break them up with a rake to create a seedbed to overseed your entire lawn.

Fall overseeding is a great way to introduce to our lawn new varieties of grasses that have improved disease-resistance, drought tolerance and/or aesthetic qualities like color and texture.

Once you break up the soil cores, top dress with a  1/4 or an inch of compost and rake it into the soil from the cores. Then broadcast the seed over the seedbed and rake lightly to barely cover the seeds. Keep the newly seeded area moist (not sopping wet!) until the seed germinates.