Take a soil test. The test analyzes the soil's fertility and pH (degree of acidity or alkalinity). This information is essential to know what to add and what not to add. Test kits are available from your local Cooperative Extension, Soil & Water Conservation District offices and online.
Mind your soil's pH. Soil pH should be between 5.5 - 6.5. Most Maine soils are acidic with a pH of 4.8 to 5.2. Lime increases pH and can be applied anytime during the growing season. Pelletized dolomitic limestone is easiest to apply.
Measure your lawn. You need to know your lawn's square footage to properly calibrate your spreader. Excessive use harms the environment, is costly, increases need for mowing and can burn grass plants.
Don't over apply. If you return the clippings, lawns older than 10 years may not need any fertilizer. If older lawns begin to thin or lose color, application of nitrogen may be necessary. New lawns need nitrogen for seed germination and to get ahead of the weeds. Total nitrogen applied per 1000 square feet should not exceed 2 pounds on older lawns and 3 pounds on younger lawns. Best time to apply fertilizer is September. Spring applications encourage weed germination. Use slow release formulations of nitrogen (water insoluble nitrogen, some manures, activated sludge, sulfur-coated urea) that "spoon feeds" small amounts of the nutrient over many weeks. Only apply at 1/3 to 1/2 the labeled application rate. Do not apply before heavy rainfall! Excess nitrogen washed into our bays promotes algae growth and chokes marine life.
Skip the phosphorus. It is rarely essential for established Maine lawns. Since a soil test will likely reveal ample phosphorus, use phosphorus-free fertilizer on existing lawns. Small amounts of phosphorus may be desirable, however, for improved germination when seeding a new lawn. Mix starter phosphorus into root zone and never apply on soil surface. Follow soil test recommendations.
How much green is too green? The iridescent, emerald-green lawn acquired by overfeeding with fertilizers, especially nitrogen, is actually unhealthy turf that’s under stress. In this condition, the lawn is vulnerable to plant diseases, weeds and drought.