Frequently Asked Questions About Lawn Care
(To download a PDF version of Lawn Care FAQ, "Click Here" .)
What Grass Seed Grows Well in Western Washington?
To establish a lawn in western Washington, choose a combination of
turftype tall fescue grasses and turftype perennial rye grasses. A mix that
adds up to about 90% of these two grass seed types will grow well in either sun
or light shade in western Washington. Turftype perennial ryegrass takes full
sun and stands up to traffic. Turftype tall fescues are adapted to shadier
locations. In combination, the mix works for a lawn in average light conditions.
Mixes containing fine-leaved fescues or chewings fescues will also establish
well. Fine-leaved fescues offer bright green color, and will take some shade,
but do not take heavy use.
Many commonly-grown grass types from other areas of the United States will
not thrive in western Washington's cool, dry summer climate. AVOID mixes with
high concentrations of Kentucky blue grasses. DO NOT PLANT Zoysia, bermuda,
dichondra, centipede, carpetgrass, St. Augustine, or mondograss. Buffalograss
isn't suitable for western Washington, though it may thrive in eastern
How Do I Fertlize the Lawn?
Regular fertilization helps to maintain good lawns. In western
Washington, apply N-P-K fertilizers in a 3-1-2 ratio (3 Nitrogen - 1
phosphorous - 2 potassium.) Examples of fertilizers in this ratio would be
21-7-14 or 15-5-10. Sulfur enhances color and helps control some lawn disease
problems. Selecting a fertilizer that contains sulfur, or applying the nitrogen
two times a year in the form of ammonium sulfate will help your lawn receive
sufficient sulfur, at least 2 pounds per 1000 square feet per year.
Apply at the proper times. Washington lawns should receive 4 pounds of
nitrogen per 1,000 square feet each year; divide this into 4 separate
applications. In western Washington, a suggested schedule is 4 applications:
November 15-December 7; April 15; June 15; and September 1. Be sure to include
the winter fertilization, November 15-December 7, which helps to maintain lawn
health through winter.
Moss in the Lawn?
Mossy lawns in western Washington result from native mosses moving into
areas where the lawn isn't growing strongly. Shade, poor drainage conditions,
or thin grass areas will encourage moss. Lawns grow best when established in
sun, on flat (not steeply sloped) areas, and when properly fertilized and
watered. (A slope of about 6 inches in 100 feet is excellent.) Mow the lawn
frequently. Good basic lawn care is the best defense against moss.
To rid a lawn of moss, correct the basic growing conditions. If the
area is significantly shaded, consider replacing the lawn in that location with
a shade-adapted ground cover such as vinca (Vinca minor), pachysandra
(Pachysandra terminalis), or ajuga (Ajuga reptans). Lawn grasses can't grow
where water stands; correct drainage problems.
Moss infestations can be killed out with chemicals (many of these
contain iron). The moss will turn black, and the residue must be raked out of
the lawn. Then overseed the bare spots with new grass seeds. If the lawn
doesn't fill in, the moss will creep back into the spaces.
Does Lime Kill Moss?
Lime applications DO NOT control moss. The lime can help grasses grow
better, which will help to resist moss infestations. If a soil test reveals the
pH of the soil to be below 5.5, liming may help the lawn. When putting in a new
lawn, add 100 pounds of lime per 1000 square feet, and work it in thoroughly
before seeding. With established lawns, lime applications every three years may
help, but do not exceed 35 pounds per 1000 square feet because the lime will
not work into the lawn properly. These applications won't get rid of moss, but
they will help the lawn grow more strongly so it can fight moss.
Can I Put Grass Clippings Back on the Lawn?
Regular and frequent mowing helps to maintain lawns in good health.
Research now shows that dragging the clippings off and discarding them isn't
necessary. "Grasscycling," which means allowing the clippings to drop
back on the lawn and break down naturally, can contribute to lawn health by
returning nitrogen from the leaves to the grass roots as the clippings
disintegrate. Lawns suffer nutrient deficiencies more often when clippings are
To succeed with "grasscycling," mow frequently. Mow often
enough so that the cutting removes no more than 1/3 of the length of the grass
blade. If turf has grown so long that mowing will necessarily remove more than
1/3 of the total grass blade, the clippings cannot be dropped back on to the
lawn. They won't break down well. Mowing when the grass blades are dry also
helps with grasscycling. Mulching mowers, which help with clipping recycling by
chopping grass blades into fine bits, are a sensible choice if new mowing
equipment is being purchased.
What Makes Thatch?
Thatch is caused by the accumulation of roots and dead grass stolons,
and it builds up faster with some grass types than with others. The layer of
dead material acts just like the thatch on an old-fashioned roof, and it repels
water. If it's more than about 1/2 inches thick, it will keep air, water, and
nutrients from reaching the grass roots and turf quality will be poor.
Remove thatch layers when the lawn is growing strongly --usually
February through April. The grass must fill in and regrow after the thatching
process. Reseeding bare spots may be necessary after thatching.
Leaving grass clippings on the lawn, "grasscycling," is not a
cause of thatch build-up.
When and How Often Do I Water the Lawn?
During western Washington's low-rainfall summers, extra watering is
necessary to maintain lawns in excellent condition. However, adding water will
not compensate for lawns improperly installed with insufficient root
development or too little soil under the roots. Lawns require 6 to 8 inches of
well-drained soil under the roots for best establishment. Sprinkling
poorly-established lawns is a waste of water.
To determine how often the lawn needs water, dig around grass roots.
Irrigate when the top 2 inches of soil become dry and crumbly. Water slowly and
deeply, wetting the grass down to the deep root level. Frequent light
sprinklings cause shallow root growth and will not result in healthy lawns.
Overwatering the lawn can reduce oxygen levels to the roots, and will stifle
good growth. Further, overwatering encourages some lawn weeds such as
buttercups, annual blue grass, and speedwell.
WSU turf specialists suggest that the best time to water is early in
the morning, around 4 a.m., which allows the grass blades to dry out thoroughly
during the day. This schedule would certainly require a timer on the system for
the lawn owner's convenience! Do not irrigate at mid day in the sun; water
applied is wasted through evaporation.
Soil type as well as depth will determine how often the lawn needs water.
Sandy soils dry out faster than heavier loam or clay soils and will ordinarily
require more frequent irrigation. Check the soil around the root level and
irrigate when it's dry to 2 inches down.
How Can I Remove Lawn Weeds?
Properly established lawns will fight weeds well, as the grass grows
thickly enough to prevent weed seeds from germinating. However, weeds in lawns
are inevitable, and can originate with weed seeds sprouting in topsoil as the
lawn is first seeded. Proper watering, frequent mowing, and keeping the lawn
fertilized will often allow a new lawn to choke out these weed seedlings. Do
not use any weed killing (herbicide) products on lawns before they are 2 months
If perennial weeds persist despite good lawn care, ther first step ist
to get the weed identified. Dandelions, with their brilliant yellow flowers,
are easy to spot. Other weeds may be less obvious, and it's suggested that the
lawn owner take a look at WSU Extension Bulletin EB0607 "Lawn Weed Control
for Homeowners" which contains clear identification of the most common
lawn weeds. Identification is vital to establish good management for the weed
Washington State University turf specialists do not recommend the use
of combination fertilizer/weed killer (herbicide) products, because the
application of these products puts herbicides where they are not necessarily
required. Spot treatments, with a product registered to treat the particular
weed, are more appropriate.
My Grass Looks Clumpy and Coarse.Why?
All lawns will change in texture and color as they age. After a period
of 5 years or so, all lawns will contain infestations of wild grasses and
weeds, as the lawn goes through a natural succession. Maintaining a pure,
perfect stand of only 1 or 2 turf grasses requires constant labor and inputs of
pesticides, and is suitable only for areas such as putting greens where the
turf contributes to the success of the business it supports. Concentrate on
keeping the lawn in good general health and recognizing that some weeds are a
natural part of lawn life. "Clumpy" grasses are wild grasses moving
in on the lawn.
A lawn which is substantially overtaken by perennial weeds may need to
be removed with a non-selective herbicide and replanted properly. However,
tolerating some changes in texture and appearance over time is a natural part
of living with lawns in western Washington.
Soil Conditions for Planting a New Lawn:
Establishing a new lawn successfully depends more on the preparation of
the ground before planting than on whether the lawn choice is seed or sod. Lawn
failures are often caused by poor soil conditions under the roots.
Many times soil surface left for planting after new construction is
infertile subsoils, with rocks, lumps, and building detritus left in it. The
texture may vary from sands and gravels to heavy, poorly drained clay areas.
The best soil texture for a lawn is a sandy loam, containing 60%-70% sand and
30%-40% combined silt and clay.
If the soil isn't well-drained, do not try to amend a heavy clay by
dumping sand into it. Adding sand doesn't work, nor does adding gypsum. Amend
the soil with organic material, which will help in creating better structure.
Use compost, manure, aged sawdust, ground bark, or other organic (previously
living) materials. Spread 2 inches on top of the ground and work it in
thoroughly 6 to 8 inches down. Getting it completely incorporated is important,
because spots of organic material in clumps may decompose and cause a low spot
in the finished lawn. Rake away clods and remove large rocks and litter.
Seed or Sod for New Lawns?
Seeding a new lawn is economical and works well if done when the
weather is right for seed germination. April and May or September and October,
up to about October 15, are good months, when there's rainfall available and
the soil and air temperatures allow seed germination. Other months of the year
are far less successful for seeding lawns. Be sure to use seed adapted to
western Washington conditions.
Sod can be laid nearly any time, and provides an attractive
"instant" lawn. The choice between seed and sod depends on how
quickly it's necessary to get the lawn completed. Give sod the same good soil
preparation as seeded lawns, be sure it makes firm contact with a prepared soil
bed, and keep it irrigated through spells of low rainfall.
Failure with lawn establishment results most often from improperly
prepared soil underneath the lawn, which affects the lawn negatively whether
seed or sod is used.
Does My Lawn Have Cranefly?
Western Washington lawns have very few insect pests, but the European
cranefly can be a problem. Populations of craneflies vary --some years will
show high infestations, while in others far fewer. One area may have high
infestations, a nearby area may have few.
Lawn damage from cranefly results as the larval form chews on roots and
crowns of grass from underground, damage generally showing up in March, April,
or May. Browned, dead spots result. To check for the presence of these larvae,
or "leatherjackets," dig up a square foot of turf and flip it over.
Count the larvae, which are brownish gray and about 1/2 inch long. If the lawn
has less than 30-35 larvae in 1 square foot, no treatment should be necessary.
The lawn can outgrow the infestation. Support the turf with water, fertilizer,
and good mowing practices.
The larvae result from eggs laid in early fall by the adult cranefly,
an insect about 2 inches long resembling a large, loosely-constructed mosquito.
The adult cranefly doesn't bite or harm mammals. Throughout the winter, the
larval populations are eaten by birds and killed by weather variations, so that
waiting until spring to examine lawns for damage is a good practice for
gardeners. Let natural conditions work on the population first.
A natural,biological control for cranefly, a living agent called
beneficial nematodes, is now widely available. This is sold as
"BioSafe," "ScanMask," or "Exhibit." Follow
instructions precisely; this biological control isn't harmful to mammals, bees,
or other beneficial insects.
Insecticides often sold to treat cranefly infestations are toxic to
children, pets and birds. Use these only if the infestation exceeds 3-35 per
square foot and the lawn shows damage. Treat only affected lawn area. Try other
methods before resorting to chemical insecticides.
Get Rid of These Moles!
Moles, commonly found in western Washington, can irritate gardeners by
raising mounds and tunnels of loose soil and damaging lawns. They do not eat
bulbs or flowers, but they may disturb ornamental plantings with their digging.
They seek worms and other soil dwellers for food.
The only sure way to get rid of moles is to place a scissors trap
properly in the run but body-gripping traps are not legal to use in Washington
State. There are also several kinds of mole-baits and chemical repellents that
can be purchased. The old-style pelletized baits usually do not give
satisfactory control but the new "gel-baits" and
"worm-mimic" baits may be effective.
Digging moles out or killing them with a shovel when they are actively
mounding can be effective but is time-consuming.
Repellent plants, chewing gum, flapping windmills, and other reputed
remedies don't work.
What Causes Mushrooms to Come Up in My Yard in the Fall?
Mushrooms are the fruiting bodies of fungi, many of which are involved
in the breakdown process of dead and decaying organic matter in the soil. In
this sense then, they are beneficial and do not harm your living garden plants.
Another large group of fungi, named "mycorrhizal," are also
beneficial; living on the roots of trees and shrubs, helping these higher
plants absorb nutrients from the soil. In turn, the woody plants supply
carbohydrates to the fungi. These, too, reproduce annually and their fruiting
bodies, in the form of mushrooms, often pop up during the moister and cooler
periods of the year.
Some species of fungi attack the roots of woody plants and eventually
kill them. However, these pathogenic species are in the minority. One fairly
common one is called Armillaria, or honey fungus; its honey-colored mushrooms
appear at the base of infected plants. This disease fungus normally only kills
plants that are under stress from other causes - often it's poor drainage, or
overwatering that does it.
There are no chemical controls to deal with mushrooms coming up in your
yard. Rake them up and destroy them before they have a chance to develop
reproductive spores. Dethatching lawns sometimes will eliminate, or at least
reduce, mushrooms in lawns since that removes their food source.
Mushrooms in the Lawn?
Rings or clumps of mushrooms poking through lawns are common problems
in western Washington. They result from fungal presence underground; the
mushroom is the "fruit" of the fungus infestation.
Get rid of mushrooms by raking them off the grass. Support the lawn
with proper fertilization and watering when needed. No chemicals are registered
for dealing with lawn mushrooms, thus no chemical treatments can be done.
It's also possible to drench the affected area with detergent and
water, in early spring. Poke holes about 6 inches deep, about a foot apart,
through the surface, and drench the area daily for a month. Use 1 to 2 quarts
of water per square foot, with 1 to 2 tablespoons of liquid detergent per 3
gallons of water.
My Lawn Has Red Thread. How do I Get Rid of It?
This fungal disease occurs in cool, moist regions and is particularly
common in western Washington. The disease develops rapidly during periods of
high moisture and cool temperatures; fall through spring. Fescue and perennial
rye grasses are most commonly affected, as can other grass types. Symptoms will
be water-soaked, darkened irregular patches from 2 - 24 inches in diameter.
They gradually become bleached or tan-colored. When the disease is advanced,
the fungus produces light pink or red strands of mycellium (fruiting bodies)
from the tips of the leaves.
Problems with red thread can be reduced by maintaining proper
fertility. Follow a regular lawn fertilization program using a fertilizer with
a nitrogen-phosphorous-potassium ratio of 3-1-2. Late fall applications of
fertilizer are particularly important. In summer, keep the turf adequately
watered. Current research indicates that fertilizers with sulfur, such as
ammonium sulfate, can also help reduce lawn disease problems.
Red thread disease is primarily cosmetic and rarely kills turf grasses.
It can be effectively controlled by good lawn-care practices. Be certain to
fertilize, mow properly, and water in summer. No chemical controls for
homeowner use are registered or available
Horsetails Have Invaded My Lawn. What Will Get Rid of Them
Without Hurting My Lawn?
Horsetail control is difficult. The best management for it in lawn is
constant mowing that keeps the plants down. This does leave the problem of the
altered texture in the lawn where the horsetails come up, but short mowing will
reduce that. In theory, if the plants are constantly mowed, they weaken. They
are, however, long-lived and persistent no matter what measures are taken.
There are no chemicals registered to control these weeds in a lawn. Keeping the
lawn well fertilized and watered will help the turf grow strongly and may serve
to deny light to the horsetails. Be sure to mow down the early season
"fruiting bodies," spikes of prominent light-tan color that appear in
late winter before the familiar fronds of green horsetail foliage.
My Lawn on a Steep Bank is Dead. What is the Best Way to Handle
In late summer, many lawns that appear dead are simply dormant. Many
will green up again with the arrival of fall rains.
However, maintaining a lawn on a steep slope is a constant difficulty.
Many homes in the hillier sections of Seattle and in many maritime Northwest
suburban areas have lawns installed on slopes.Watering is difficult and mowing
is a challenge. Lawns do best when placed on sunny, well-drained, level spots.
One suggestion is terracing the bank and planting drought tolerant
plants, such as various smaller juniper cultivars (check nurseries for
evergreens that are drought tolerant.) Making this change takes time and work
initially but will save trouble as the years go by, and it will enhance the
Other areas unsuitable for turf can be parking strips, very shady spots
under trees (moss heaven), in the shadow of buildings. Also unsuitable are
poorly-drained sites which stay soggy nearly year round, and areas of heavy
traffic that compacts the soil. Turf that is constantly walked on will wear
down faster than it can grow back. Choose another landscaping solution rather
than enduring the frustration of re-planting grass where it cannot thrive.
No landscapes are entirely maintenance-free. If you install plants,
even drought tolerant ones will require summer care, including water for the
first two or three seasons. However, it's vital to reduce the waste of
struggling with constantly failing turf put into unsuitable spots.