You should fertilize your Northern Ontario lawn twice per season for best results: once in late May after the grass has greened up and begun active growth, and again in early September to strengthen roots before winter. This two-application approach aligns with the natural growth cycles of cool-season grasses in our climate zone and delivers maximum benefit with minimal product. Martin Services provides professional fertilization and weed control across Powassan, North Bay, and surrounding communities.
Late May: Spring Application
The spring fertilizer application should happen after your lawn has fully greened up and been mowed at least twice — typically late May in the Powassan and North Bay area. Applying too early, while the grass is still waking from dormancy, wastes product because the roots are not yet actively absorbing nutrients. A balanced fertilizer with a moderate nitrogen content feeds the spring growth surge without overstimulating the lawn into excessive top growth that requires more frequent mowing. This application also helps the lawn outcompete weeds during the critical spring establishment period.
Early September: Fall Application
The fall fertilizer application is the most important of the year. Applied in early September, it feeds the grass during its strongest natural growth period when cool temperatures and shorter days signal the plant to focus energy on root development and carbohydrate storage. A fall fertilizer with higher potassium content strengthens cell walls and improves winter hardiness — critical in Northern Ontario where lawns endure five months of snow cover. A well-fed fall lawn emerges from winter greener, thicker, and more resistant to spring diseases like snow mold.
What About Summer Fertilizing?
In most Northern Ontario situations, summer fertilization is unnecessary and can be counterproductive. Fertilizing during the heat of July and August can stress cool-season grasses that are already slowing their growth in response to high temperatures. If your lawn looks healthy through summer, let it coast on the spring application. If specific areas need attention, targeted spot treatment is better than a full lawn application during the heat.
Want professional lawn fertilization? Call Martin Services at (249) 506-9211 for a free estimate. We serve Powassan, North Bay, and all surrounding areas.