Cool-season grasses like Kentucky bluegrass, perennial ryegrass, and tall fescue thrive in regions with cold winters and moderate springs and falls—like New Hampshire. One of the keys to a thick, healthy lawn in these climates is choosing the right fertilizer. In this blog post, we break down the most effective types of fertilizer for cool-season lawns and when to use them.

1. Slow-Release Nitrogen Fertilizers

Slow-release fertilizers deliver nitrogen steadily over time, supporting sustained growth without rapid spikes that can stress the grass. Look for products containing MESA, Meth-EX, SCU (sulfur-coated urea), or XCU. These are great for long-term feeding and help reduce the frequency of applications.

Best time to apply: Spring and fall

2. Quick-Release Nitrogen Fertilizers

These fertilizers provide an immediate boost, making them ideal for lawns that need a fast green-up. They include sources like ammonium sulfate or urea. However, they can burn grass if overapplied and require more frequent applications.

Best time to apply: Early spring or when quick recovery is needed

3. Fertilizers with Pre-Emergent Weed Control

Combination fertilizers that include pre-emergent herbicides are ideal in early spring. These prevent crabgrass and other weed seeds from germinating while feeding your lawn.

Best time to apply: Early spring (before soil temperatures reach 55°F)

4. Iron-Enriched Fertilizers

Iron helps cool-season grasses maintain a rich green color without forcing excessive growth. These fertilizers are ideal for summer applications when nitrogen needs to be reduced but color is still important.

Best time to apply: Summer

5. Winterizer Fertilizers

These are high-nitrogen blends designed to prepare your lawn for dormancy and encourage strong root development. They improve turf density and color heading into winter.

Best time to apply: Late fall

Final Tips for Fertilizing Cool-Season Lawns

• Always water your lawn after applying fertilizer unless the product is labeled otherwise.
• Use a broadcast or drop spreader for even distribution.
• Perform a soil test annually to choose the most appropriate fertilizer formula.

Choosing the right fertilizer at the right time is essential to keeping your cool-season lawn healthy year-round.