Maintaining a lawn

Keep your lawn healthy using good maintenance practices. Grow a healthy lawn by properly fertilizing, liming, aerating, mowing, topdressing, overseeding, and watering.

Mowing

Mow high when it's dry

  • Grass cut at a height of 6 to 8 cm (2 ½ to 3 inches) will develop a deep, extensive root system and grow thicker. Grass this height helps the soil to retain its moisture better.

Sharpen your blade

  • Sharpen your mower blade in the spring and keep it sharp.
  • Grass recovers more quickly and easily from a clean cut than when it's torn.

Leave lawn clippings on your lawn after mowing

  • Lawn clippings compost, slowly releasing nitrogen for the grass.
  • Under wet spring conditions, remove thick layers of clippings (over 0.5 cm thick) to avoid smothering your grass.

Watering

Water deeply but not too often

  • Too much watering can lead to poor growing conditions and disease problems.
  • Water only when your lawn needs it, usually no more than once a week when there is no rainfall.
  • Apply at least 2.5 cm (1 inch) of water. Put a tuna or pet food can on your lawn to measure how much you've watered. Stop watering when it's full.
  • Consider the soil type and surface features. Grass growing on compacted, fine soil or on slopes needs lighter, more frequent watering.

Water in the morning

  • Watering in the morning reduces water lost from evaporation and wind.
  • Watering in the evening leaves the grass wet for longer, increasing the risk of disease.
  • Grass growing near large trees may need to be watered more often, because the tree roots absorb much of the soil's water.

Don't panic during hot weather

  • In extended hot, dry periods, a lawn may wilt, turn brown, and become dormant.
  • A healthy lawn can survive several weeks in a dormant state.
  • Common grass varieties like Kentucky bluegrass and fine fescues will turn green again when regular moisture conditions return.

Fertilizing

Compost is a great fertilizer that supplies your lawn with nutrients needed for plant growth.

  • Apply it at any time of the season.
  • Mix it into the soil before seeding or laying sod, or spread it in a thin layer raked over your existing lawn.

Commercial fertilizers usually contain three major nutrients:

  • nitrogen (N), to promote leaf growth
  • phosphorus (P), for root growth
  • potassium (K), which is essential for stress resistance

The three numbers on the packaging show the proportions of these nutrients. For example, a 21-7-7 formulation contains 21% nitrogen (N) and 7% of each of phosphorus (P) and potassium (K).

  • All-purpose turf fertilizers usually have an N-P-K ratio of 4-1-2.
  • Fertilizers with a slow-release form of nitrogen are better because they release nutrients uniformly, and there is less risk that excess fertilizer will leach away from the root zone.
  • How often and how much you should fertilize depends on the type of soil, the type of grass, and site and weather conditions. Follow all instructions on the product label.
  • A lower rate is generally used in spring and early summer than in early and late fall.
  • Organic fertilizers release more nutrients as the temperature and moisture levels increase, so you shouldn't fertilize when conditions are likely to be hot or dry, usually from mid-June to early August.
  • Combination products containing a herbicide and a fertilizer (weed and feed type) should only be used if your lawn has a widespread weed problem and a nutrient deficiency.

Have your soil analyzed every few years by a professional lab. This will tell you more specifically what type of fertilizer you will need and how much to use. It will also show if the pH of your soil is right for growing grass.

Overseeding and replacing sod

Most healthy lawns recover from damage. Depending on the type of grass, fast-growing lawns will fill in areas that have been thinned by insects or other types of damage.

If bare patches do not fill in quickly, weeds may set in.

Overseeding

Spreading grass seed on your lawn regularly will ensure that it remains dense.

  • Overseeding is best done in late summer to early fall.
  • Topdressing with compost or topsoil can be done at the same time. Apply topsoil first, then seed over top and press or rake seed into the soil.
  • Using the proper type of grass seed is very important for lawns in shady areas.

Replacing sod

  • Cut out the dead or damaged area to about 2 cm deep.
  • Rake the soil and add some fertilizer.
  • Lay down the new piece of sod.
  • Step on it or roll it to ensure good contact with the soil.

Keep the new seed or sod well watered until the new grass is established.

Aerating and dethatching

Aerating

Aerating involves making holes in your lawn either by pushing a rod into it or by extracting a plug of soil. This allows a better flow of water, air, and vital nutrients to the plant roots, making it easier for them to grow. This does not, however, apply to soil types containing clay. It is best to aerate in late summer, then topdress and/or overseed.

Signs that you need to aerate your lawn:

  • The ground is hard and compacted.
  • Thatch is building up.
  • Water does not penetrate well.
  • Weeds like prostrate knotweed and clover are present.

There are two types of mechanical aerators:

  • solid-tined machine that drives spikes into the ground
  • core machine that removes small plugs of thatch and soil

Sandals or shoes with 6 cm (2 ½ inch) spikes can be used for small lawns.

Do not roll your lawn in spring, because this may increase compaction problems.

Dethatching

Thatch is a tough mixture of dead grass and roots that gathers above the soil surface. In a healthy lawn, insects, earthworms, beneficial fungi, and other microorganisms break down thatch and aerate the soil.

Excessive watering, over fertilizing with nitrogen, and heavy use of insecticides and fungicides may decrease the number of soil organisms needed to keep thatch levels down.

Thatch that is more than 1 cm (½ inch) thick can prevent water, air, and nutrients from getting to the roots. Too much thatch can also harbour harmful insects and diseases.

  • Remove excess thatch with a heavy rake or de-thatching equipment.

Checking for problems

  • Check your lawn often to detect pests or other problems early.
  • It may be harder to see insect damage in a dormant lawn.

See Dealing with lawn problems for more information.

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