Lawns requiring frequent pesticide use, in particular herbicides, may have an underlying problem that is causing the repeated invasions of pests such as weeds. Correcting the problem leads to a healthier lawn that can resist weed invasions.
Good soil conditions are important for healthy lawns. Many lawns are growing on soils high in clay, compacted, and poorly drained. Aerating and topdressing with organic matter will improve these conditions. Repeated aeration may be necessary to adequately reduce soil compaction and increase the levels of soil oxygen. Another option is starting over and amending clay soils with organic matter.
Thoroughly preparing soils before seeding or sodding is critical. Organic products can also introduce more of the already naturally occurring soil organisms and work symbiotically with the grass plant, each giving the other what they need for better growth. A soil test is recommended to be sure other factors like pH and levels of nutrition are adequate for grass growth. It is far easier to amend the soil prior to sodding or seeding than to think you will be come back later and fix it.
Make sure the proper grass species is used on the site. Full sun and sun/shade environments call for different grasses. In addition, consider the standard of quality desired and the intended use of the site. Each has a role in what grass to select. Kentucky bluegrass is the primary species for northern Illinois lawns in full sun; in some cases mixed with perennial ryegrass and/or fine fescues.
For shade areas, shade-tolerant Kentucky bluegrass cultivars are commonly mixed with fine fescues, yet these shady grasses do not stand up to activity very well even though there are Kentucky bluegrass cultivars in the mix.
Cultural practices also play a big role in the health of the lawn and need for pesticides. Proper watering includes irrigating as lawns need it and getting moisture down into the root zone. Proper fertilizing includes supplying adequate nutrients and proper soil pH.
In particular, avoid excess or lack of nitrogen when using synthetic fertilizers, fertilize during cooler weather (especially early and late fall), and use controlled-release nitrogen fertilizers to avoid the swings in food availability. Don't apply high rates of nitrogen in spring.
Proper mowing has a major impact on lawn health. Many lawns are mowed too short, allowing weeds to invade and other problems to appear. Mow between 2½ and 3 inches and mow often enough so no more than one-third of the leaf blade is removed in any one cutting.
Manage lawn stress factors such as thatch, shade, and soil compaction. Core aerating on a regular basis is an excellent practice to consider, especially for sodded lawns over clay soils. Spring and fall are good times to aerate.
Occasionally, problems will still come up that require special management. Start by identifying the problem, then look at control options; cultural organic and chemical. When the situation warrants (even when using organic management practices), some weeds for example will need to be controlled chemically or mechanically prior to lawn establishment. When using pesticides read, understand, and follow all label directions.