How to Fertilize the Lawn

Lawn fertilizers are distinguished by the N-P-K numbers on the front of the bag. These letters stand for Nitrogen (N), Phosphorus (P) and Potassium (K) and represent the percentage by weight of each of those nutrients in the fertilizer. Nitrogen helps plants grow and green up, Phosphorus stimulates deep root development and Potassium provides all around health and disease/drought resistance. Choosing the right combination depends on a number of variables including sunlight exposure and climate.

You should typically fertilize your lawn every 6-8 weeks, as when it grows and gets cut, the nutrients in the soil deplete and need to be replenished. 

In Canada you should fertilize grass in late spring or early fall, ideally when temperatures are consistently between 15-25°C. Avoid fertilizing during extreme heat or cold. It's beneficial to water the lawn a few days before fertilizing to ensure the soil is moist but not saturated. 

Provinces like Ontario, British Columbia, and Quebec generally follow this guideline. However, specific timing may vary based on local climate conditions and grass types. Always refer to regional gardening resources or consult with local experts for precise recommendations tailored to your area.

Follow the directions on the bag carefully. Determine the size of your yard then measure out the right amount of fertilizer. Depending on the measurement, using the whole bag may mean you're applying too much or too little. Never apply more fertilizer than the soil test or fertilizer label instructs. Even distribution is key. A great way to do this is to use a quality spreader, which ensures that the nutrient particles are spread evenly over the lawn, which will keep the health and colour consistent throughout.

Fill the spreader while standing on pavement so you can clean up any spills. Sweep any fertilizer that lands on your walk, driveway or patio back onto the grass. Remember: 100 percent of any fertilizer that remains on a hard surface will end up in the storm drain or in streams and rivers.

If you don’t own a spreader, you can easily rent one online or at your nearest Home Depot location.

Begin fertilizing with your spreader at one end of your yard. This will provide a convenient starting and stopping point for each pass. Pay attention to how much you're overlapping each pass to avoid double-dosing the grass.

If your lawn is oddly shaped, make header strips (an already mowed piece of grass where a lawn mower can be easily turned around) around its entire perimeter. Leave a 20-foot safety zone around wells and streams where no fertilizer is applied.

Once the header strips are down, walk back and forth between them, spreading the fertilizer. Begin walking before you open the chute and close it just before you reach the far header to avoid leaving piles of fertilizer at your starting and stopping points. Shut off the spreader if you must travel over pavement.

Walk at a steady pace. Your speed affects the rate at which the fertilizer is applied. A moderate speed is best. Watch for dips in the ground, which can cause fertilizer to spill out. Walk in a straight line so the wheel tracks from the first pass will give you a guideline to follow on the next one.

Unless you're using a liquid or combination fertilizer, water immediately after you apply fertilizer so it moves down to the roots. To see if watering is needed (and how often), be sure to check the label instructions on your bag of grass fertilizer.

After fertilizing your lawn, ensure proper watering to prevent burning. Follow the fertilizer instructions for watering frequency. Mow regularly at the recommended height, usually 2.5 to 3.5 inches, removing no more than one-third of the grass blade. 

Avoid mowing when the grass is wet to prevent disease spread. Keep an eye out for weeds and treat them promptly. Maintain aeration and overseeding if necessary to keep the lawn healthy and thick. 

Regularly inspect for pests and diseases, addressing any issues promptly. Continue these maintenance practices throughout the growing season for a lush, healthy lawn.