MARCH 10, 1997
Spring lawn rejuvenation--keep it natural!
Spring green grass cheers the winter-tired eyeballs, and summer goes well with lawns. It's wonderful to have a place for children to play, to set up a family badminton or croquet game, or to stretch out in a hammock and watch the clouds sail by. Lawns make an attractive green frame for setting off landscape shrubs and flowers.
For many people, lawn care requires lots of extra summer irrigation, applications of fertilizer, and use of pesticides (particularly herbicides for invasive broadleaf weeds like dandelions). Could lawn care be simplified to reduce maintenance and chemical inputs?
It certainly can, and the first task is to think of what the lawn contributes to the landscape. If it's primarily a play field for children and romping dogs, the turf will gradually be invaded by some native grasses and weeds, which are then mowed down for comfort. Perfection isn't required in a play area. If the lawn is in a "show" area, a different maintenance standard may prevail, and more care may be devoted to weed control. Whatever the use of the lawn, a few simple principles can help with keeping it looking good while still reducing pesticide use.
There's a principle in landscaping called "Right Plant, Right Place." Some of the difficulties people have with lawns relate to the misplacement of the grass. This could be described as the hopeful optimism that a lawn will grow anyplace we want it to be. Lawns have specific growth needs, just as rhododendrons and roses do. If it's in the "Wrong Place," the turf won't grow well.
First, is the lawn getting enough sunlight? I admit that in early March, nothing in the Pacific Northwest is getting enough sunlight, but the lawn should be placed where it gets at least 6 hours of light daily. Lawns that are shaded grow poorly and ultimately run to moss. Grass, when we think about its origin, is a prairie plant, accustomed to wide open spaces for light. The maritime Pacific Northwest was, before we began rearranging it, primarily a forested area. Grasses don't grow well inside forests. So if the lawn is too shaded, you may want to consider replacing the shadiest parts with locally-adapted ground cover. Check with your county Cooperative Extension office for the bulletin #68 "Ground Covers for Western Washington," which is available in Seattle by calling 206-296-3900 during normal business hours. In Tacoma, call 206-591-7170 between 9 a.m. and 3 p.m. Monday through Friday.
The soil underneath the lawn also contributes to its success or failure. Does it drain well? The winter of 1996-97 has certainly given all of us a chance to observe drainage patterns. Some people with lakefront property had high water over bulkheads and across onto the lawn. Others have had low spots that filled with water and just didn't drain. Lawns won't survive over the long term in soggy ground. If it's impractical to install drainage or regrade to correct the drainage, remove lawn from that soggy spot.
Finally, for optimum health, the turf requires good soil under its roots. Many of us are accustomed to observing turf that has an inch or two of sparse roots struggling to keep its blades growing. One ofthe most common sources of lawn trouble is the inadequate depth of soil beneath the sod or seed. The optimum is 6 to 8 inches of well-drained soil, before the sod goes down or seeding is done. Many people have the unfortunate situation of finding themselves with a lawn that looks fine at first but declines rapidly after a few months or years. This is often traceable to poor soil preparation, no matter how good the quality of the sod when it arrived on the property. Sod is sometimes unrolled over two inches of mix, with hardpan beneath. If your lawn is persistently soggy, dies out in spots, or is hard to keep watered in summer, dig out a one foot square section and check the soil quality under the roots.
So, you say, the lawn is in sun, drains well, and has good soil for six inches under its roots? That's a great start to successful lawn maintenance.
Aerating the lawn is often done during early spring, and March is a great month for it if the lawn has dried a bit and isn't soggy. (If walking on it produces a squish-squish sound the turf is too wet for aeration.) A day when the soil is damp but not sopping is perfect. Aeration pulls 'plugs" of old turf and roots, allowing water to penetrate the grass better. After aerating, overseeding with a Northwest adapted lawn mixture such as a mixture of fine fescues (such as chewings, creeping red, and hard fescue) and perennial rye will help the lawn fill in and grow thickly. Perennial ryegrass is a good choice for areas that will get traffic, such as play areas.
Topdressing (spreading) about 1/2 inch of compost over the lawn after aerating and overseeding will also help the seeds thrive. Seeding the lawn in mid-March, April, or early May works well, because natural rainfall can help keep the new seeds moist until they germinate. Be sure to water newly seeded areas if there's no rain; allowing the seedlings to dry out will kill the new shoots. The stronger the lawn grows, the better it will resist invasive weeds.
Mow regularly. When grass is growing actively, this may mean mowing about every 5 to 7 days. If possible, try "grasscycling," allowing the grass clippings to fall back onto the turf using a mulching mower or standard rotary mower. The clippings will break down and provide additional nutrients, including nitrogen, for the grass.
With these practices in hand, the lawn should grow thickly enough to outgrow most weeds. Relax and enjoy the turf--but remember, it needs to be "Right Plant, Right Place."
Visit WSU's Agriculture Site on the World-Wide Web at http://www.cahe.wsu.edu.