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Updated Sep 30, 2022

Preventing Lawn Problems

Learn tips for how to grow a dense, healthy lawn. A healthy lawn resists invasion by moss, weeds, insects, and diseases. If your lawn is not meeting your expectations, consider a lawn renovation.

Follow these steps to maintain a healthy lawn:

  • Maintain the right growing conditions needed for strong, healthy grasses. Healthy lawns resist moss, weeds, insects, and diseases.
  • Perform regular lawn maintenance. Activities include: mowing, weeding, fertilizing, overseeding, and watering. Dethatching and aerating also help.
  • Understand that lawns change over time. After you sow lawn seed or lay sod, a mixture of desired grasses and broadleaf weeds, grassy weeds, and moss will evolve.
  • Soil drainage, soil fertility, sunlight, water stress, and how the lawn is cared for and used will influence how your lawn looks over time.
  • Set realistic expectations for your lawn. Match the lawn standards you want to maintain with the right maintenance schedule.

For more information:

Jump To

  1. Grow a Healthy Lawn
  2. Consider a No-Till Lawn Renovation
  3. Perform Regular Maintenance
  4. Consider Dethatching & Aerating
Grow a Healthy Lawn
  • A healthy lawn resists invasion by moss, weeds, insects, and diseases.
  • Plant grass species best suited for your area.
  • Plant disease-resistant cultivars or mixtures.
  • Lawn grasses require full sun to thrive. Lawns grown in shady areas will require more care to maintain to high standards. Or learn to tolerate moss for lawns in shady areas.
  • Apply fertilizer and water to grow a lawn that matches the lawn standards you wish to maintain.
Side-by-side photo showing sparse lawn and dense lawn

OSU Turfgrass Management Program

The photo shows a side-by-side comparison of a sparse lawn (left) and a dense lawn (right). Maintaining a dense stand of grasses is the best way to keep moss, weeds, insects, and diseases at bay.

Healthy, dense stand of turf grass

OSU Turfgrass Management Program

Maintaining a healthy, dense stand of grass in your lawn requires planning and regular maintenance.

Consider a No-Till Lawn Renovation
  • Consider a total lawn renovation if moss, weeds, insects, or diseases are overwhelming your lawn area.
  • Late summer is the best time of year for a lawn renovation.
Photo contrasting two methods of no till lawn renovation.

OSU Turfgrass Management Program

Lawns change over time. The lawn renovation methods shown in the photo establish a new stand of grasses.

Exposed soil in lawn renovation

OSU Turfgrass Management Program

The goal in lawn renovation is to expose the soil for seeding.

The photo shows two renovation techniques:

  • Complete renovation (left): herbicide dethatch, and reseed
  • Partial renovation (right): dethatch and reseed

Both treatment areas in the photo are ready for seeding.

Learn More about Lawn Renovations

For more information about renovating your lawn, see Practical Lawn Establishment and Renovation  (OSU Extension Service).

Perform Regular Maintenance


  • Mow regularly. For most lawns, a mowing height of 2–3 inches is recommended.
  • Use a mulching mower (has a special blade and enclosed deck) or reel mower to chop up debris into small pieces. Mulch mowing recycles nutrients to the lawn.
  • Mow weekly during most of the growing season.
  • Mow twice per week when the grass is growing quickly during mid-late spring as needed.
Reel lawn mower

mtreasure, iStock

Reel mowers effectively cut grass in lawns. Make at least 2 passes over the entire area. If large pieces of debris remain, make a third pass to chop it up finely.

Mulch mower blade compared to regular blade

OSU Turfgrass Management Program

Mulching mowers can return about ½ of the yearly nitrogen (plant nutrient) requirement for common lawn species. The red-colored mower blade in the photo chops up grass clippings into small pieces. The clippings decompose quickly.

Lawn mower on its side showing the blade

Keep your lawn mower blades sharp. Sharpen them at least once a year. Take the mower and/or blade to a repair shop if needed.

Mowing Tips

  • Cut only 1/3 of grass height at each mowing.
  • Make at least two passes over your entire lawn area. Go at a 45-degree or 90-degree angle to your first pass. This method helps to avoid ruts and compaction from the mower.
  • Rake up excess lawn clippings that don’t get finely chopped.
  • Mow higher in periods of stress such as dry or hot weather. The longer leaves promote root growth to absorb water from the soil.
  • If you don’t use a mulching mower, bag and remove the lawn clippings.

Apply Grass Seed in Spring or Fall

  • The grasses in lawns naturally thin out over time. Keep your stand of grass thick and robust by applying grass seed regularly.
  • Apply grass seed or lawn patch to thin areas in the spring and late summer or early fall. Cover up bare soil with grasses.
  • Apply grass seed over your entire lawn at least every two years before it thins out for the worse.
Seed spreader and bag of seeds on lawn

Weston Miller, Oregon State University

Seed spreaders evenly distribute grass seeds over the entire lawn area.

Lawn patch product on lawn with bag nearby

Weston Miller, Oregon State University

For small bare spots, apply lawn patch products. They combine seed, mulch, and fertilizer.

How to Use a Seed Spreader

  • Follow the instructions on the seed spreader tool and seed packaging for best results.
  • Split the amount needed for the entire lawn into two lots.
  • Apply the first lot going in one direction.
  • Apply the second lot at a 90-degree angle.
  • This process ensures even and thorough seed coverage.

Fertilize, But Not Too Much

  • Unfertilized lawns tend to be thin, light green, or brown in color. They often have moss and weeds mixed with grasses.
  • Unfertilized and over-fertilized lawns are both prone to insect pests and disease problems.
  • For low-maintenance lawns, apply fertilizer once in the fall to promote robust growth the following spring. Apply fertilizer in late spring and summer too for higher-maintenance lawns.
  • Mulch mowing provides about the equivalent of one fertilizer application per year.

Slow-release fertilizers

  • Slow-release fertilizers include organic fertilizer options and synthesized fertilizer products that say “slow release” on the package (coated to keep the nutrients from dissolving in water).
  • Slow-release fertilizers provide a steady stream of plant-available nutrients over time.
  • Slow-release fertilizer products are less likely to dissolve in water and move into waterways than soluble fertilizer products.
Fertilzer spreader on lawn

Dole08, iStock

Lawns grow vigorously when enough nutrients are available, especially nitrogen. Use a fertilizer spreader like the one shown in the photo. They help to distribute the fertilizer evenly across the lawn area.

Lawn fertilizer package

Look for fertilizers with a high percentage of nitrogen (the first number in a fertilizer ratio). The example lawn fertilizer label has a ratio of 30–0–10. This example is for a conventional fertilizer (synthesized). Text on the label states “With Slow-Release Feeding.”

Organic lawn fertilizer package with fertilizer ratio of 11–2–2

Weston Miller, Oregon State University

Organic lawn fertilizers are also available. Organic means that the material is derived from natural sources such as blood meal and minerals. The example product label has a fertilizer ratio of 11–2–2.

Lawn Watering Decision-Making

  • Lawns can survive the summer without irrigation by going dormant and turning brown.
  • Unirrigated lawns often have moss and weeds mixed with grasses. They don’t stand up to heavy wear.
  • Watering is required if you want your lawn to look green through the summer. Plan to water from mid-May through September. Some locations or dry years might require irrigating earlier or later than these dates.
Pop-up sprinkler watering lawn

A buried irrigation system with pop-up sprinklers and a timer is the best method to irrigate high-maintenance lawns. Learn to use your irrigation controller for best results.

Sprinkler attached to hose watering lawn

"sprinkler" by grace_kat is marked with CC BY-SA 2.0.

You can also use a sprinkler attached to a hose to water your lawn. Use a faucet-mounted timer to help you water regularly.

Gloved hand holding screwdriver

Weston Miller, Oregon State University

The photo shows an example screwdriver that could be used to test the moisture of soil in a lawn area.

Lawn Watering Tips

  • Use several range gauges or empty, shallow food cans (such as tuna) placed on your lawn to measure how much water you apply.
  • Don’t apply more than 0.5 inches of water at a time.
  • Plan to water 3–4 times per week. Each watering should be between 0.25–0.5 inches.
  • Adjust the amount of water you provide each week through the season. Determine a baseline. Add more when the weather is hot and dry. Water less when it is cooler.
  • Perform routine maintenance on sprinkler heads.
  • Water in the morning, so grass can dry quickly.
  • Provide good soil drainage.

How to Test the Moisture of Your Lawn

  • Use a screwdriver as a soil moisture gauge to determine if you are watering enough or too much.
  • Push the screwdriver into the lawn surface.
  • If it easily penetrates to the handle, ease back on watering.
  • If the ground is hard and it is difficult to insert the screwdriver, water more.

Check Lawn Soil PH, Amend as needed

  • Lawns grow best with soil pH between 6.0 and 6.5.
  • Check your lawn’s soil pH. Amend as needed.
Worker in laboratory

We recommend sending soil samples to laboratories for analysis. Professional soil tests are more accurate than do-it-yourself soil testing options. Ask your soil testing lab to interpret the results and provide recommendations for amending soil pH for lawns.

Soil test kit and supplies

Soil test kits are useful to measure your soil pH. They don’t tell you how much amendment to add to correct the pH.

Learn More Soil Testing

For more information about soil testing, see How do I test my garden soil?  (OSU Extension Service).

Consider Dethatching & Aerating


  • Thatch is built-up organic material at the base of grass plants. When it builds up, grasses die back and weeds and insect and disease pests might take hold.
  • Remove thatch if it exceeds 1/2 inch deep.
  • Apply grass seed to your lawn after dethatching.
  • See Thatch in Home Lawns  (PNW Plant Disease Management Handbook) for more information.
Dethatching rake

Michel VIARD, iStock

Dethatching rakes effectively remove thatch and debris from lawns. This material needs to be raked up and removed.

Detaching machine with grass that needs to be raked

PaulMaguire, iStock

The photo shows a power detaching machine. The machines leave removed thatch on the lawn surface. This material needs to be raked up and removed.


  • Aerate your lawn if the soil is compacted or water does not penetrate well.
  • Aerating helps air to penetrate the soil. Aerated soil helps grow healthy lawn grasses.
  • Apply grass seed to your lawn after aerating.
Lawn aerating tool

Hand tools effectively aerate soil in lawns.

Power core aerating machine

Sherry Barr Photography, iStock

Yard equipment rental stores rent power aerating machines.

Content provided by  Weston Miller.

 Reviewed by OSU Department of Horticulture.

Photo of Weston Miller

Weston Miller

Project Founder and Content Writer

Weston Miller served as Community and Urban Horticulture faculty for Oregon State University Extension Service for Clackamas, Multnomah, and Washington Counties. Weston is an author for content for this website. He developed funding partnerships with Portland area agencies to initiate and build out the Solve Pest Problems website focused on this goals: