Summer Lawn Care in London, ON
Summer in London (June–August) brings hot, humid conditions that challenge both lawns and lawn owners. July and August temperatures regularly reach 30–35°C with high humidity, creating ideal conditions for fungal disease while stressing cool-season grasses.
June is the last month of strong growth before summer heat slows everything down. July and August in London are about survival — keeping the lawn alive through heat and humidity. Fungal diseases like brown patch and dollar spot thrive in Ontario's humid summers.
Kentucky Bluegrass in London enters summer stress mode by mid-July — growth slows and the lawn may go dormant (tan) during extended heat. This is normal. Tall Fescue handles Ontario summers better due to deeper roots. Fine Fescue may struggle in full sun during heat.
Summer priorities in London: water 25mm per week, applied in 2 deep sessions before 9am; mow at 75–90mm to shade soil; allow dormancy rather than forcing growth; and watch for grubs in August — skunks digging at night is a key warning sign.
Ontario's cosmetic pesticide ban means cultural practices are your primary defence against summer problems. A healthy, well-mowed, properly watered lawn resists disease and insects far better than a stressed one.
Great Lakes & Ontario Zone — Summer Overview
Hot humid July–August. Brown patch risk in Kentucky Bluegrass. Water 25mm per week. Allow dormancy rather than stressing lawn in heat.
Summer Tasks for London
1. Water 25mm per week
Ontario summers are hot and humid. Water deeply 2x per week before 9am. A tuna can placed on the lawn measures sprinkler output — aim for 12–13mm per session.
2. Mow at 75–90mm
Raise mowing height for summer. Taller grass is more drought-tolerant and shades out crabgrass. Never cut more than one-third of blade height in a single mow.
3. Allow summer dormancy
Kentucky Bluegrass goes dormant (tan coloured) during July heat — this is normal. Maintain 25mm of water every 3–4 weeks to keep crowns alive. Do not force growth with nitrogen in summer heat.
4. Watch for grubs in August
European Chafer and Japanese Beetle grubs feed on roots through August. Signs: irregular brown patches, turf lifts like carpet, skunks digging at night. Apply nematodes in August when soil is moist.
5. Control broadleaf weeds
Apply selective broadleaf herbicide on dandelions, clover, and plantain in June while actively growing. Avoid spraying in temperatures above 27°C or when rain is forecast within 24 hours.
Best Grasses for London in Summer
Frequently Asked Questions
How often should I water my lawn in London, ON during summer?
During summer in London, ON, water your lawn deeply once or twice per week rather than lightly every day. Aim for around 25mm of water per session, ideally early in the morning before 9am to minimise evaporation. Adjust based on rainfall — a rain gauge helps track natural precipitation.
Is it normal for my lawn to turn brown in summer in London?
Yes, Kentucky Bluegrass and other cool-season grasses commonly go dormant (turn tan/brown) during extended hot, dry periods in London, ON. This is a natural survival mechanism, not death. The lawn will green up when temperatures cool and moisture returns. Water once every 3 weeks during dormancy to keep crowns alive.
What mowing height should I use in summer in London?
In London, ON, raise your mowing height to 75–90mm during summer. Taller grass shades the soil, retains moisture, reduces crabgrass germination, and develops deeper roots. Never remove more than one-third of the blade length in a single mow. Mow more frequently rather than cutting too much at once.
How do I prevent grubs in London during summer?
European Chafer and Japanese Beetle grubs are common lawn pests in London, ON during summer. Apply beneficial nematodes in August when soil is moist and warm. Signs of grub damage include irregular brown patches, turf that lifts like carpet, and skunks or raccoons digging at night. Early detection is critical.
Should I fertilise my lawn in summer in London?
Avoid heavy fertilising during summer heat in London, ON. If the lawn is actively growing and not drought-stressed, a light application of slow-release fertiliser in June is acceptable. Never apply nitrogen to a dormant or heat-stressed lawn — this can burn the grass and promote fungal disease.