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Ask Angie: How to reseed a thin, sparse lawnBest way to reseed depends on the condition of your lawn

Angie Hicks
Angie Hicks MCT

Dear Angie: What's the best way to reseed my yard so I don't destroy the grass that has started growing? We used a grass that grows well in our hot and humid climate, and in partial sun. Much of the seed "took," but the grass is patchy and thin. I'm thinking we didn't lay down enough seed. I need advice on the best reseeding method. — Jessica M, Greenville, S.C.

Dear Jessica: Rest assured that spreading seed over grass won't hurt your existing lawn. But if the new grass isn't growing well, you likely didn't properly prepare the soil or keep the seed sufficiently moist the first few weeks.

In other words, it takes more than simply tossing out grass seed and hoping for the best to transform thin turf into a lush lawn.

If you're experiencing only a few small bare spots, spot-seeding may be your best solution. Rake the bare area and lightly spread the seed.

For larger patchy areas, it's better to perforate or aerate the soil and then spread seed or slit-seed. A "slit seeder" or "slice seeder" is a gasoline-powered machine that slices even rows into soil and drops seed into the rows, for more soil-seed contact and a higher percentage of germinated seed than you'll get with just spreading seed. Slit seeders are most typically used to apply seed over an existing lawn, where mature grass or weeds may block new seed.

After seeding, add a quality starter fertilizer. To protect seed and help keep it moist, cover with a thin layer of topsoil, compost or other weed-free organic material.

Early fall is generally a good time to reseed a lawn, but review instructions for the specific type of grass you want to grow. For best results, new grass needs a month or more after germination to grow strong before the first frost. Seeding can also be done in spring, if grass has time to mature before the height of summer heat.

While adding seed won't hurt existing grass, be careful not to walk on newly germinated seed until the plant is strongly established.

Common mistakes to avoid include over- or under-watering. The lawn layer that contains the seed must be kept moist, but not soaked, for the several weeks it takes to germinate. Water about three times daily, at late night or early morning, midday and late afternoon.

Once the seed germinates, water regularly and deeply until the grass plant matures, usually an additional couple of weeks.

You can rent a core aerator or power slit seeder for at least $65. Quality seed can cost $3 to $4 a pound, depending on the variety. Buy 3 to 4 pounds per 1,000 square feet for overseeding after core aeration. Buy 6 to 8 pounds per 1,000 square feet when power slit-seeding. With slit seeding, apply half the seed in one pass, then repeat in a different direction to create a pattern of diamonds or squares.

If you plan to hire a company to aerate and reseed, expect to pay about $50 to $65 per 1,000 square feet, for a minimum $200 to $300 for a 4,000-square-foot lawn. Fertilizer will usually be a separate charge.

When hiring a lawn service, get bids from several who have good reviews on a trusted online site and are appropriately licensed and insured. Get all pertinent details in writing.

Angie Hicks compiles the best advice from the most highly rated service pros on Angieslist.com to answer your questions. Ask Angie your question at askangie@angieslist.com.