Lawn problems
Weeds are good indicators of the health of your lawn 
Weed seeds are everywhere and your soil contains 1000s of them that can lie dormant for years. The reason they remain dormant is because they don't have the right conditions to grow. Those conditions are temperature, moisture, and sunlight. The key is sunlight. A properly maintained and healthy lawn of thick turf grass is so thick that it blocks out the sunlight from reaching down to the weed seeds. Without that key ingredient, those seeds just don't do anything. Now, for whatever reason, when a lawn loses its vitality and begins to thin out, sunlight reaches the dormant seeds and they suddenly come to life in a big way.
The weeds can of course be removed, but until the underlying cause of the thinning lawn is corrected, they'll just keep coming back.
There are several basic causes for a lawn to thin out: compacted soil, excess thatch, lack of proper nutrients, and too much shade. All of these conditions can be corrected in a relatively short period of time if the right steps are taken.
Compacted soil
Compacted soils are the most difficult to correct and take the longest to repair, but is often the major cause of a poor lawn. Regular aeration is the easiest way to correct this. Aeration also helps reduce thatch buildup. For severe cases, an aeration treatment combined with a top-dressing application may be required.
Additional nutrients
Turf grasses quickly use up nutrients from the soil. These nutrients need to be replaced regularly. Leaving your lawn clippings on the lawn helps, but doesn't replace enough nutrients to be the sole source of nutrients. Professional lawn fertilizers contain a balanced blend of nutrients and micro-nutrients necessary for healthy growth. These need to be applied at the proper time of the year to be completely effective.
Improving shaded areas
Lawns that try to live in the shade have it tough. For grass to grow it needs sunlight to generate food necessary for healthy growth. If you have shady areas there's a few things you can do to improve the situation. There are some varieties of grass that have been developed that will tolerate shade better than others. Depending on your circumstances, this might be an option.
If the shaded areas are caused by trees on your property, have the branches of your trees thinned out. This will allow more light to filter through, but it also improves the health of your trees. Thinning needs to be done by professionals who understand when and where to make the cuts.
If none of the above corrections are feasible, then the other alternative is to plant something other than grass. There are many different ground covers that thrive in the shade.
Occasional weeds in a healthy looking lawn are to be expected from time to time and spot treatment is the preferred method for removal and preventing their spread.
Everett, Bellevue, Redmond, Issaquah, Seattle, Lynnwood, Bothell, Woodinville, Edmonds, Renton, Kent, Maple Valley, Auburn, Snohomish, Marysville, Duval, Monroe, and Tukwilla, WA. If you live in one of these communities, please call our office for a free estimate for your lawn and landscape concerns.
