Lawn Care Through the Year

Why our lawns are different

Lawn grasses here have to cope with about 375 mm of precipitation a year, hot dry winds in July and August, and winters that swing between deep cold and bare, thawed ground during chinooks. Many city yards also sit on compacted clay or construction fill with a thin layer of topsoil, so roots stay shallow.

Grass that suits Lethbridge

Alberta Agriculture’s lawn advice is to use a blend of several Kentucky bluegrass varieties with some creeping red fescue. Most prairie lawns are built on that mix, and for good reason. Here’s how the common choices compare:

Mowing high and grasscycling

Mowing height is the single easiest thing to get right. Alberta Agriculture recommends mowing high, about 6 to 7.5 cm (2.5 to 3 inches), and many prairie gardeners go to 8 cm in midsummer. Taller grass grows deeper roots, shades the soil so it stays cooler and moister, and shades out weed seeds before they sprout.

• The one-third rule. Never cut off more than a third of the blade at one mowing. To keep a lawn at 7.5 cm, mow before it reaches about 11 cm. Cutting more than that “scalps” the grass and sets it back for days.
• Raise the deck in the heat. In July and August, raise the mower by about 2.5 cm. Taller grass handles heat and drying winds better.
• Keep the blade sharp. A dull blade tears the leaf tips, which turn brown and lose more water. Sharpen at least once a year. See Mowers, trimmers and edgers and our sharpening page.
• Change direction each time you mow, so the grass grows upright and the wheels don’t wear ruts in the same places.
• Mow when the grass is dry. Wet clippings clump, and wet clay compacts under the wheels.

Leave the clippings: grasscycling

Short clippings left on the lawn break down in days and return nitrogen and other nutrients to the soil. University of Minnesota Extension estimates that clippings add the equivalent of about one fertilizer application a year. They don’t cause thatch; thatch is mostly made of tougher stems and roots.

Alberta Agriculture suggests keeping the layer of clippings thin (under about 1 cm). If the grass got away on you, mow twice, or rake the long clippings off and add them to the compost. Grasscycling also saves trips to the yard waste site, which the City of Lethbridge runs seasonally for grass, leaves and branches.

Watering deep, and letting it rest

A lawn needs about 2.5 cm of water a week in summer, counting rain. Give it in one or two deep soakings rather than a little every day. Deep watering pushes roots down into the soil, where it stays moist longer. Light daily sprinkling keeps roots near the surface, where they dry out on the first hot, windy afternoon.

1. Measure what you give. Set a few straight-sided cans or jars on the lawn and run the sprinkler until they hold about 2.5 cm. Time it, and you’ll know how long to run that sprinkler from then on.
2. Water early in the morning. It’s cooler and usually calmer, so less is lost to evaporation and wind drift, and the grass dries off during the day.
3. Go slow on clay. Clay soaks water up slowly. If water starts running onto the sidewalk, stop, let it soak in for half an hour, then finish. Two shorter sessions back to back beat one long run-off.
4. Water by need, not by calendar. If grass stays flattened after you walk on it, or turns a dull blue-grey, it’s thirsty. If it rained 2 cm this week, skip a watering.
5. Give sunny slopes and the ground under big trees a little more. Both dry out faster.

Letting a lawn go dormant

In a dry summer, Kentucky bluegrass and fine fescues protect themselves by going dormant: the leaves turn tan, but the crowns and roots stay alive. Strathcona County calls this letting the lawn “go golden”. It’s a perfectly good choice in Lethbridge, especially when the City asks for water conservation.

• Iowa State University Extension says cool-season lawns can usually stay dormant for 4 to 6 weeks without serious harm. In a longer drought, one soaking of about 2.5 to 4 cm every four weeks or so keeps the crowns alive.
• Pick one approach and stick with it. Greening a dormant lawn up and letting it brown again uses up its reserves.
• Keep foot traffic and mowing to a minimum. Brown crowns crush easily.
• When rain returns, the lawn greens up over a week or two. Reseed patches that truly died in late August or early September.

Aeration, dethatching and overseeding

Core aeration for compacted clay

Core aeration pulls small plugs of soil out of the lawn. It lets air, water and roots get into compacted clay, helps soil life break down thatch, and cuts runoff. A quick test from the City of Calgary: dig out a wedge of lawn about 15 cm deep. If the roots only reach the top 2 to 5 cm, the soil is probably compacted.

• When: the City of Calgary’s advice for Alberta is May to June or mid-September, when the grass is growing and can fill in quickly. Once a year is plenty for most lawns.
• Prepare: water deeply two days before so the soil is moist but not soggy. Mark sprinkler heads, shallow sprinkler lines and any buried cables.
• Do it right: use a machine that pulls cores (hollow tines), not one that just pokes holes. Go over the lawn in two directions.
• Leave the cores on the lawn. They crumble back in within two to four weeks, or you can break them up with a rake.
• Skip it on lawns in their first year, and where rocks or tree roots sit right under the surface.

Dethatching: only when it’s needed

Thatch is a layer of tough stems and roots between the green blades and the soil. A thin layer is normal. Alberta Agriculture says to act only when thatch is thicker than about 1.25 cm, and recommends core aeration as the gentlest fix; power raking tears out live grass too. Cut out a small wedge and measure the spongy brown layer before you rent a dethatcher. A light spring rake to lift matted grass once the lawn is dry is a different, much gentler job.

Overseeding and topdressing with compost

Thin lawns let weeds in. Overseeding fills the gaps:

1. Pick your time. Late August to mid-September is best: warm soil, cooler nights, and fewer weed seeds sprouting. Spring works too, once the soil has warmed.
2. Open the soil. Rake thin spots hard, or overseed right after core aeration so seed lands in the holes.
3. Seed and cover. Spread seed of the same kind of grass you have, then a thin layer of screened compost, about 0.5 to 1 cm, raked in so the grass blades still show.
4. Keep it moist with light daily watering until the new grass is up, then cut back gradually to deep, infrequent watering.

Feeding a lawn naturally

A grasscycled lawn needs much less feeding than most get. Too much nitrogen makes soft, fast growth that needs more mowing and water, and builds thatch.

• Clippings first: free, continuous feeding.
• Compost topdressing: a thin layer after aeration feeds soil life and slowly improves clay. The City of Lethbridge sells finished compost at the Waste and Recycling Centre and holds giveaway events.
• If you use lawn fertilizer, keep it modest. Alberta Agriculture suggests feeding only when the lawn needs it, ideally guided by a soil test. Common Alberta timing is a light feeding in late spring and another in late summer.
• Go easy on late fall feeding. The University of Saskatchewan lists fall fertilizing among the conditions that encourage snow mould.

Weeds without sprays

Weeds move into bare and thin spots. A dense lawn mowed high is the best weed control there is, because the grass shades the soil and weed seeds can’t get the light they need to sprout.

• Thicken the lawn: overseed thin areas every year or two, especially along sidewalks and under trees.
• Mow high: 7 to 8 cm grass shades out many low weeds.
• Water deeply, not often: frequent light watering keeps the surface moist for sprouting weed seeds.
• Dig dandelions by hand. The taproot can run 15 to 45 cm deep and regrows from pieces left behind. Dig when the soil is moist, slide a dandelion digger straight down beside the root, lever and pull slowly. Fill the hole and sprinkle in grass seed. If it comes back, dig again.
• Get them before they seed. Mowing off dandelion flowers before they turn to puffballs cuts down next year’s crop.

Our Natural weed control page covers more weeds and methods.

Snow mould, chinooks, dogs and ants

Snow mould after long snow cover

After a winter with long-lasting snow, especially where snow was piled up, you may see matted patches covered with fuzzy white, grey or pinkish threads as the snow melts. That’s snow mould, caused by fungi that grow under snow. It usually disappears on its own as the lawn dries and warms, and lawns usually recover well.

• In spring: once the lawn is dry, gently rake the matted patches to let air in, and put the debris in the compost. Wear a dust mask if you have allergies or breathing problems. Overseed any thin spots once the weather warms.
• To prevent it: keep mowing at your normal height right into fall so the grass doesn’t go into winter long and floppy, rake up fallen leaves, avoid fall fertilizing, and don’t pile shovelled snow onto the same patch of lawn all winter.

Winter dry-out from chinooks

Chinooks can strip the snow off a lawn and leave the grass in warm, dry wind and strong sun while the soil underneath is still frozen. Exposed slopes and spots by heat-reflecting walls suffer most, showing up as straw-coloured patches in spring. Give the lawn a deep soaking in October before freeze-up, especially after a dry fall. In a long, open, dry winter, hand-water new lawns on a mild day when the ground has thawed (established lawns usually get by), then disconnect the hose. Rake out and overseed dead patches in spring.

Dog urine spots

Brown patches with a dark green ring are usually from dog urine. The cause is the concentrated nitrogen, acting like a spill of fertilizer, not the urine’s acidity. Penn State Extension says the only proven fix is to water the spot right after the dog goes. Training a dog to use a mulched or gravel corner helps too. Penn State also notes that urine-changing supplements don’t address the nitrogen and should only be used after talking to your vet. Rake out and reseed dead patches.

Ant hills

Ants are mostly a nuisance in lawns, and they eat other insects and loosen soil. Rake the mounds flat before mowing so the soil spreads out. If a nest is right where you don’t want it, Washington State University’s advice is to flood it repeatedly with the hose every few days until the colony moves.

Before blaming insects for a brown patch, rule out drought, dog spots and compacted soil. Our Pests, hail and other problems page covers yard pests in general.

Less lawn, more yard

Lawn is great for play, picnics and dogs. Lawn on a hot, steep bank, or a strip you have to drag a hose to, is mostly work. Consider trimming yours back to the parts you really use.

See Xeriscaping and water-wise yards for plant lists and how to convert lawn without chemicals. A rain barrel on a downspout, which the City of Lethbridge offers a do-it-yourself guide for, catches June rain for the beds in July.

Month-by-month lawn plan

Every year is different. Watch the weather and the lawn more than the calendar.

For the rest of the yard, see the Spring and fall yard checklists and the garden section’s Month-by-month garden calendar.

Sources

• Alberta Agriculture and Rural Development, Lawn Care Tips (Agdex 273/14-1).
• City of Calgary, Lawn aeration (property owners’ guide).
• City of Calgary, Managing water: what you can do (lawn tips).
• Strathcona County, Outdoor water saving tips: lawn watering.
• City of Lethbridge, Water conservation page; news release on seasonal Yard Waste Sites; Waste and Recycling Centre page.
• University of Saskatchewan, Gardening at USask: Snow mold.
• Sara Williams, Low-maintenance, non-irrigated lawns (column courtesy of the Saskatchewan Perennial Society).
• Colorado State University Extension, Fine fescues for lawns.
• University of Minnesota Extension, Mowing practices for healthy lawns.
• Iowa State University Extension and Outreach, Dormant lawns.
• Penn State Extension, Dogs vs. lawns.
• Washington State University Hortsense, Lawn and turf: Ants.
• Oregon State University, Solve Pest Problems: Dandelion.
• University of Nebraska–Lincoln, Winter watering.
• Environment and Climate Change Canada, Canadian Climate Normals 1991–2020, Lethbridge Airport.