DNRP > SWD > Natural Yard Care > FAQs

Frequently Asked Questions

1. Where can I recycle my lawn mower?
2. What care does my lawn need in the springtime?
3. What about spring care for the rest of my yard?
4. How are worm-castings different from regular compost?
5. When is the best time to mulch?
6. What is the difference between compost, organic fertilizer and synthetic fertilizer?
7. What does it mean to top dress a lawn?
8. What is grasscycling or mulch-mowing?
9. How does a mulching mower work?

1. Where can I recycle my lawn mower?

Visit http://your.kingcounty.gov/solidwaste/naturalyardcare/mower.asp for information on lawn mower recycling.

2. What care does my lawn need in the springtime?

For an easy-care lawn all year long, mow regularly, but a little longer (about 2 inches for most lawns). A mulching lawn mower makes this easy.

Pull weeds now, while they’re small and the ground is soft (and before they go to seed).

Fertilize after May 1 (after spring grass growth slows) with a “natural organic” or “slow-release” fertilizer.

Improve thin patches of the lawn by raking (to expose soil), scattering a Northwest-adapted grass seed, and covering with ¼ inch of compost.

Water new grass if the weather gets dry, to help it establish deep roots.

3. What about spring care for the rest of my yard?

Prepare garden soil by digging in compost when planting flowers, gardens, and perennials.

Pull or hoe weeds now, before they go to seed. Long-handled weeding tools make it easy.

Try less-toxic bug, moss, and weed control products.

Spread mulch (wood chips, bark, compost, leaves, etc.) around trees, shrubs, and perennials to control weeds.

Conserve water with soaker hoses, water timers and watering wands that put water just where it's needed.

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4. How are worm-castings different from regular compost?

Worm compost (vermicompost) is rich in many nutrients, so you can use less than you would of regular yard waste compost. Vermicompost is usually too rich for use for sprouting seeds, but is useful as a mulch or an addition to potting soil.

5. When is the best time to mulch?

Spring is the best time to mulch to keep soil moist over summer, and fall is a good time to use leaves as a cover against cold in the winter. Be sure when installing mulch that your plants are not buried too deeply. Thick mulch can be harmful to shallow-rooted plants such as rhododendrons. It’s not a good idea to put out mulch in the heat of the summer on dry soil. The mulch will actually prevent water from reaching the plant roots. A good rule of thumb is 1-3 inches of mulch depending on your plant material. Be sure to keep mulch a few inches away from the trunks of trees and shrubs as this can cause disease problems.

6. What is the difference between compost, organic fertilizer and synthetic fertilizer?

Compost is decomposed organic matter that strengthen the soil, making it more porous for insects and earthworms and for water storage.

Organic fertilizers are like compost in that they are typically made from the remains or by-products of organisms. Like compost, but unlike synthetic fertilizers, they improve soil structure and increase fungal and bacterial activity in the soil. Organic fertilizers are labeled N, P and K guaranteed by analysis, whereas compost is not.

Synthetic fertilizers typically contain petroleum products. They are not as stable in the soil, often releasing quickly and adding to downstream water pollution.

7. What does it mean to top dress a lawn?

Top dressing means to spread a thin layer of compost on top of the existing lawn. Topdressing is most effective after aerating so that the amendments get down into the soil closer to the root zone, but done alone is also beneficial. A top dressing of compost adds organic matter to soil beneath the lawn and gradually gets incorporated into the soil by worms and other organisms. About one-quarter inch of compost, applied in early spring or late fall is ideal. Before reapplying each year, check to make sure that the compost applications are disappearing into the soil (worms at work!), rather than just building up on the surface.

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8. What is grasscycling or mulch-mowing?

Grasscycling, or mulch-mowing, means leaving the clippings on the lawn to feed the soil. With mulching mowers you leave grass clippings on the lawn, where they can supply as much as 1/3 of your lawn’s necessary fertilizer needs. You save time and money when you don’t need to haul clippings or pay for fertilizers. Electric or hand mowers have the added advantage of being quiet, and running on power that will not add to our region’s air pollution. Here are some interesting facts about grasscycling:
• Each year, the average King County household generates nearly three-quarters of a ton of grass clippings and other yard waste for curbside pick up. Grasscycling helps grow a healthy lawn while reducing the amount of yard waste you make.
• Leaving your grass clippings on the lawn, by mulch-mowing, adds nutrients to your lawn. In one year, grass clippings contain about 3 pounds of nitrogen, 1 pound of phosphorus, and 3 pounds of potassium per thousand square feet of lawn. Grasscycling supplies 1/3 of your lawn’s necessary nutrients per year – so you can cut out one of your fertilizer applications each year.
• Gas-powered lawn mowers contribute about 7 percent of the air pollution in our region.
• Mowing for one hour with a gas-powered lawn mower creates more pollution than driving from Safeco Field to the Tacoma Dome and back.

9. How does a mulching mower work?

Mulching mowers, when used as designed by manufacturers, chop clippings finely and blow them down into the lawn so they disappear and won’t be tracked into the house. Remember not to use the bag attachment with your mulch mower. Contrary to some beliefs, mulching mowers do not cause thatch. Instead, overuse of fertilizers, pesticides and water all lead to thatch build-up.