How green is your valley

Organic lawn-care professionals emphasize "cultural practices" as the key to a healthy, attractive lawn without the use of chemically synthesized products. They say organic cultivation builds up soil, eliminates health risks to children and pets, and requires less watering. Among their recommendations:

• Use fertilizers made of natural products such as corn gluten (a corn byproduct), animal manure, and composted organic materials. Organic fertilizers release nutrients over months and build up the microorganisms that make for healthier soil. This will thicken your grass, leaving leave less room for weeds to grow and eliminating the need for a weed killer.

• Mow lawns at higher levels - at least three inches. The grass will shade the sun from the soil, making it harder for weed seeds to germinate. Leave the cut grass on the lawn to help build up the soil.

• Lower your "weed-free" standard. There will probably always be a few weeds crashing your garden party, but the environmental cost of chemical herbicides is too high. Regional lawn-care professional Carl Brodeur uses a vinegar-based weed killer called Nature's Avenger and a hand tool called the Weed Hound to remove certain problem weeds.

• Don't water when you don't need to. Frequent shallow waterings encourage shallow roots rather than deep ones. If your lawn is too dry, water thoroughly so that a spade inserted into the turf reveals moistened soil six inches down.

• Start a new lawn or improve a current one in autumn, using practices such as aeration and overseeding. Lawn-care specialist Rebecca Lipton says she aerates by removing plugs of soil to fight soil compaction and allow oxygen into the soil. "I overseed religiously," Lipton said, by broadcasting new seed over the aerated soil in the fall. Adding high quality, drought-resistant seed will improve the lawn over time.

ROBERT KNOX