One of the great myths of lawn care is that feeding with commercial fertilizer is enough to keep a lawn in perfect condition. So many companies offer lawn fertilizers — often applied in 3 or 4 steps! —that it’s easy to believe that’s what you need for a perfect lawn. In actual fact, though, fertilizer will only give you mediocre results.
The truth is that even the best soil in the world will degrade over time if you don’t add organic matter… and fertilizer, even organic fertilizer, is essentially made up of minerals and contains very little humus (decomposed organic matter). So our habit of depending solely on fertilizer to maintain the soil quality in our lawns eventually leads to “mineralized” soil, that is one where minerals abound but where humus is almost absent. Without organic matter, the soil becomes hard and compact and grass roots suffocate.
If you really want a beautiful green lawn little prone to weeds and insects, learn to topdress annually with either compost or topsoil enriched in compost.
Compost will add organic matter to the soil. And being rich in nutrients as well, it will fertilize the grass at the same time. So as long as you leave grass clippings on the lawn (another source of minerals and organic matter), it won’t be necessary to apply additional fertilizer. A thin layer of 1/4 to 1/2 inch (1 to 2 cm) of compost or compost-rich soil, applied each year (in the fall if possible, if not in the spring) is enough to keep the soil rich in humus and thus to stimulate dense, healthy grass growth .
Always follow topdressing of with an application of top quality grass seed with added white clover seeds. Weeds tend to settle in areas where the grass is thin, but if you regularly oversow with a quality product, you’ll create a very dense resistant mixture of grass and clover where weeds will have trouble sprouting and thus will remain few and far between.
One final point: although North American gardeners have become used to repairing and revitalizing their lawns in the spring, the right season to do is always early to mid-fall, from late August to mid October in most climates. If you want good results with a lawn, you have to take care of it at the right season… and for almost any care a lawn may need besides mowing, that would be fall!