How do I repair winterkill patches on my lawn?

Winterkill patches are very common in New Brunswick and almost always repairable — the key is timing your repair correctly and understanding why the damage happened in the first place.

New Brunswick winters are tough on lawns. Winterkill typically comes from a few culprits: snow mold (the most common cause here in NB), ice sheeting that suffocates grass, frost heaving that exposes roots, or simple desiccation from cold dry winds. Before you repair, take a close look at the dead patches. Greyish-white matted grass with a crusty texture is classic pink or grey snow mold — very common in our Maritime climate due to heavy snowfall and fluctuating temperatures. Ice damage tends to leave sharply defined dead zones in low-lying areas where water pooled and froze.

Timing Your Repair

Don't rush out the moment the snow melts. In New Brunswick, wait until the soil firms up — typically late April to early May — before working on damaged areas. Walking on saturated soil compacts it badly and makes recovery harder. Rake the dead patches gently with a stiff rake to remove matted dead grass and improve air circulation. For snow mold, this raking step is critical — it breaks up the fungal mat and lets the surviving grass breathe. You may find more grass survived underneath than it appeared.

Late August through mid-September is actually the best time to seed in NB, not spring. Soil is warm, competition from weeds is lower, and seedlings have time to establish before freeze-up. That said, spring overseeding works fine for smaller patches — just be patient, as germination requires consistent soil temperatures above 10°C, which usually arrives in late May in most of NB (a bit earlier in Saint John, a bit later in Bathurst or Fredericton).

How to Repair the Patches

Start by raking out all dead material until you see bare soil. Lightly scratch the soil surface with a rake or hand cultivator — about 1cm deep — to create a seedbed. NB soils are typically acidic (pH 4.5–6.0), so if you haven't limed recently, work a small amount of pelletized lime into the patch. Apply a quality seed blend suited to our climate: a mix of Kentucky Bluegrass, Fine Fescue, and Perennial Ryegrass works well across most of NB. Spread seed at roughly double the normal rate for bare patches, then lightly rake it in and top-dress with a thin layer (5–10mm) of compost or topsoil to retain moisture.

Keep the seeded area consistently moist — light watering once or twice daily until germination (10–21 days depending on temperature). Once seedlings reach about 5cm, you can back off to deeper, less frequent watering.

Practical Tips

• Don't seed too early — cold soil means poor germination and wasted seed
• Use straw mulch lightly over seeded areas to retain moisture and protect from birds
• Avoid applying pre-emergent herbicide to areas you're seeding — it prevents germination
• If the same spots die every winter, you likely have a drainage or grading issue that needs addressing, not just reseeding

When to Hire a Pro

If winterkill covers large areas (over 30–40% of your lawn), or if the same patches keep dying year after year, it's worth having a landscaper assess your drainage and soil conditions. Recurring damage in the same spots almost always signals an underlying problem. New Brunswick Landscaping can match you with a local lawn care professional for a free estimate — sometimes a proper diagnosis saves you years of frustration and wasted seed money.