Spring Cleanup Checklist for Ontario Homeowners

A proper spring cleanup sets the tone for your entire lawn season. Skip it, and you'll fight thatch, weeds and weak growth all summer. Do it right, and your lawn explodes with thick green growth by May. Here's the exact 9-step spring cleanup checklist our OSS crew uses on every property across Hamilton, Burlington, Oakville and the GTA.

When to start your spring cleanup

The right time across the GTA is usually late March to mid-April, once the snow has fully melted and the soil has thawed enough that you don't leave footprints in the lawn. Starting too early — when grass is still dormant and ground is soggy — does more harm than good.

The 9-step OSS spring cleanup checklist

1. Pick up winter debris

Walk the property and collect fallen branches, blown-in litter and debris that surfaced as the snow melted. Bag it up and clear it out before you move on to the lawn itself.

2. Dethatch matted lawn areas

Use a flexible leaf rake (not a metal thatch rake unless you have severe build-up) to lift matted grass, snow mould patches and old leaves. This lets air and sun reach the crowns.

3. Edge garden beds & walkways

A clean edge between lawn and bed is the single biggest visual upgrade you can give a property in spring. Cut a sharp 3–4 inch edge with a half-moon edger or a flat spade.

4. First mow at 3 inches

When grass is actively growing (usually mid-April), do a clean first mow at 3 inches. Bag the clippings on this first cut only — it removes any lingering debris and snow mould spores.

5. Apply pre-emergent weed control

Time this before soil temperatures hit 10°C consistently. Pre-emergent stops crabgrass and other annual weeds from germinating. Miss this window and you'll spot-spray all summer.

6. Schedule core aeration

If you didn't aerate in fall, spring is your backup window. See our when to aerate guide for timing. Aerate before fertilizing for maximum nutrient absorption.

7. Apply spring fertilizer

Use a slow-release nitrogen fertilizer formulated for spring application. Don't overdo it — too much nitrogen too early causes lush top growth at the expense of root development.

8. Refresh mulch in garden beds

Top up beds with 2–3 inches of fresh black or cedar mulch. Mulch suppresses weeds, retains moisture and instantly elevates curb appeal. Don't pile mulch against tree trunks ("mulch volcanoes") — leave a 2-inch gap.

9. Overseed thin or bare areas

Spot-overseed any thin patches. Spring overseeding is harder to establish than fall (less time before summer heat), so keep new seed beds consistently moist for 2–3 weeks.

Spring cleanup mistakes to avoid

• Starting too early — walking on soggy lawn compacts it and damages crowns
• Scalping the lawn — never cut more than 1/3 of the blade in one mow
• Fertilizing before grass is actively growing — wastes product and feeds weeds
• Skipping pre-emergent — guarantees a summer of weed pulling
• Piling mulch against tree trunks — invites rot and pests