How Long Do I Leave the Straw Hay on Newly Seeded Grass?

Purpose

• Laying down a light layer of straw mulch helps successfully germinate lawn seed. The straw, which absorbs moisture, helps keep both soil and moistened seeds from drying out between waterings. It slows evaporation, in other words. Constant moisture is crucial for grass seed, which should never dry out once it has started to germinate. Too little moisture is the leading reason new lawns fail. Straw also supports young seedlings, helping retain moisture and providing shade as tender plants acclimate to sun. Straw mulch also holds soil in place and helps prevent soil erosion until the lawn is rooted and established.

Applying

• Use one 80 lb. bale of straw per 1,000 square feet of seeded lawn area. Use wheat, oat or barley straw, but never hay, which contains seeds that will sprout as weeds. Spread a thin but uniform layer over the entire surface. When finished, you should be able to see half soil and half straw if looking straight down. People often apply straw too thickly, which can block the sun that seeds need for germination. If too much straw is applied, remove half of it -- using a pitchfork -- when seedlings stand 1 to 2 inches tall. Respread mulch "piles" created by wind immediately to avoid smothering young grass.

Removing

• If you decide to remove the straw mulch once your new lawn is well started, wait until the lawn is ready for its first mowing. This is usually when grass is 3 or 4 inches tall, depending on the variety, and when the soil is firm and fairly dry. Rather than use a leaf rake -- remember, your lawn is still very tender -- gently lift and remove straw with a pitchfork. Use the removed straw next as vegetable or flower garden mulch, or deposit it in the compost pile.

Leaving

• You can leave the straw in place to biodegrade, though if you decide to do this you'll need to supply a little extra nitrogen fertilizer -- to feed both the lawn and the microbes that will break down the straw. When your lawn is ready for its first mowing, go ahead and mow with the straw in place. The finely chopped straw can serve as mulch, along with the lawn clippings, "mulching in place" being a practice turf specialists now recommend for lawn health.