Even the best lawns need help from time to time--especially after a tough winter and a long, hot summer.  Thin lawns get thinner and bare spots get bigger without action.  So give your lawn a little extra care when it needs it.  Your reward is a healthier, greener lawn just a few months later!

Take a few minutes to look closely at your lawn.  What do you see?  If you notice bare spots, thinning grass, too many weeds, or a buildup of thatch, it's probably time to start thinking about turf renovation.  You may even want to rip up the entire lawn and start over, especially if you'd like to replant with one or more different grass species.

The best time to rejuvenate a tired lawn varies with the climate.  In the North, autumn is best.  Southern lawns, however, should be worked on either in spring or early summer.  Start by removing all trash, litter, and fallen leaves from the lawn.

Repairs
If you have bare spots, repair and sow them individually.  Cultivate the soil to a depth of four to six inches, working in a helping of balanced fertilizer.  Rake the area smooth.  Then, spread a quality seed over the area, tamping lightly with a spade to firm up the seeds.  Follow with a mulch (straw, burlap, or mesh ), and water lightly.  Continue to sprinkle the area until new growth is established.

Compacted soil can be a problem, especially in southern zones or where there is exceptionally high traffic.  Freezing and thawing in the North help break up compacted soil, but aeration is the answer in warmer climates and for problem areas.  Use aeration equipment (a special pitchfork-like tool or a spiked roller), making sure you penetrate the soil deeply and remove the "core" of compacted earth from each spike imprint.

Thatch
Often mistaken for excess grass clippings, thatch is really a decaying accumulation of fibrous leaf sheaths and roots.  A certain amount of thatch is beneficial to any lawn: it recycles plant tissues, serves as an organic fertilizer, and helps control the growth of weeds.

However, too heavy a buildup of thatch may harbor insects and disease, as well as prevent water and fertilizers from reaching and penetrating the soil.  New grass has difficulty breaking through a thick thatch layer, so it's best to remove the excess before trouble starts.

Thatch removal is easiest with a power turf thinner ("power rake").  Set the blades of the machine deep enough to make small cuts in the soil--you have to cut all the way through thatch accumulations to do any good.  Two or more passes may be necessary for a mature lawn.  A power rake will kick up a good deal of thatch as it does the job, so rake up the debris and save it for mulch or the compost pile.  You'll be surprised at the improved appearance of your de-thatched lawn after just a few days.

Over-seeding
A power dethatcher is also an excellent way to prepare a thin lawn for overseeding.  And you can improve the quality of your lawn at the same time by introducing better grasses.  Set blades of the power rake deep enough to expose the soil so that new seeds will lodge in the scratches.  After the soil-bed is prepared, select a high-quality seed.  One of the bluegrasses mixed with a little fine fescue is a popular choice, but you also might want to consider one of the fast-growing, improved perennial ryegrasses, too.  Avoid substandard mixes of seed containing annual rye, tall fescue, or other hay grasses.

Spread seed with a mechanical spreader at a rate of about half that used for seeding a new lawn (usually, sow around one to two pounds per 1,000 square feet).  Water the new seeding lightly, but thoroughly, until new growth starts; then water only to prevent soil from becoming dry.  Too much watering after the lawn is established encourages weed growth.  Mow your lawn only when new growth reaches a height of at least two inches.