Mid-August to mid-September is a good time

Mid-August to mid-September is a good time to seed bare spots in your lawn. Choose a seed mix that is appropriate for the sun at your site.

Grass grown from a mix blended for shade can look different from grass from a mix blended for sun. If your yard has adjoining areas of full sun, shade and partial shade, use a single mix of grass varieties for both sun and shade to give the lawn a uniform appearance.

Prepare the site for seeding by removing weeds and loosening the soil. Low areas will need additional topsoil. Rake out large clods, stones or debris to create a smooth seedbed. Then gently rake in the seed.

Keep the soil moist. On warm days, this may require watering two or three times a day. A light layer of compost spread over the soil helps keep seeds moist. Bluegrass takes about two weeks to germinate. It is important to keep the grass seed moist for successful germination. Watering can be adjusted to a schedule of less frequent but deeper watering as the new grass fills in.

When establishing a lawn by seed, you can expect weeds to come in before the grass can get fully established. You should mow a newly seeded lawn four times before treating with an herbicide for weeds. Pulling the weeds is also an option and can be done before mowing is necessary.

• Monitor your garden for plants that you installed this year that need extra water. There have been some good rainstorms but also spells of hot weather that have dried gardens out.

Wilting leaves and color changes in the foliage are signs that a plant may need water. Check the soil to make sure that dry conditions are the actual problem.

• Tim Johnson is director of horticulture at Chicago Botanic Garden, chicagobotanic.org.