Answer: Probably the safest approach would be to pull and hand dig the existing weeds, then reseed the bare spots and put your lawn on a regular feeding, watering and mowing schedule. A thick healthy lawn will crowd out weeds and slow weed seed germination. There are some organic products on the market if you want a little help in eliminating weeds. Gardeners Alive (www.gardensalive.com) has a whole catalog of environmentally healthy ways to take care of garden and landscape pests and problems. Check out their website and I'm sure you'll find all kinds of interesting products.
Once you've eliminated the weeds, over-seed your lawn (perennial ryegrass, fescues and bluegrass mixtures are available in your area). After the new grass has begun to grow, keep it mowed at about 2", water deeply once or twice a week, and feed your lawn with a 3-1-2 ratio (the numbers on the fertilizer bag) of nitrogen, phosphorous and potassium, applying in April, June, September and late November or early December. Once your lawn is on a regular maintenance schedule you'll have fewer weed problems and your grandchilden will have a delightful place to play.
Best wishes with your lawn!
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