Two types of grass grow in Pennsylvania, and the strategy for fertilizing each is slightly different. Fertilize cool-season grass in May, September, and November. Fertilize Zoysiagrass in April, June, and August.
Most Pennsylvania lawns have cool-season grass, which needs fertilization during the growing season – spring and fall. Each grass requires slightly different timing, however. We’ll explain below.
Warm-season Zoysiagrass grows in southern Pennsylvania, and it needs to be fertilized in spring and summer. Don’t fertilize when your grass is dormant, typically in winter and summer, because it doesn’t absorb fertilizer when it’s not growing.
Best time to fertilize, by grass type
Here are the best times to fertilize your Pennsylvania lawn.
Note: Applications are for nitrogen fertilizer per 1,000 square feet
| Grass type | March to May | June to Aug | Sept to Nov |
| Kentucky Bluegrass | 1 lb in May (late April to early June) | None | 1 lb in September (late August to early October) Optionally, apply 1 lb in early to mid-November |
| Fine fescues | 0.5 to 1 lb in May (late April to early June) | None | 0.5 to 1 lb in September (late August to early October) Optionally, apply 1 lb in early to mid-November |
| Bentgrass | 0.5 to 1 lb in May (late April to early June) | Optional 0.5 lb in June, July, or August as long as grass is not dormant. | 0.5 to 1 lb in September (late August to early October) |
| Tall fescue | 0.5 to 1 lb in May (late April to early June) | none | 0.5 to 1 lb in September (late August to early October) Additional 0.5 to 1 lb in early to mid-November |
| Zoysiagrass | 0.5 lb in April | 0.5 lb in late June and in mid-August | none |
Fertilize lawns in cooler, higher elevations between late May and early June, late August, and, optionally, in early November. At higher elevations, grass will sprout later and go dormant earlier than in the rest of Pennsylvania.
Don’t fertilize from December to February. In the winter, your lawn is dormant and can’t absorb the fertilizer, so it would be a waste of time, money, and product.
To aid color and damage recovery, you can fertilize Kentucky bluegrass, fine fescues, bentgrass, and tall fescue more often. Just be sure to:
- apply 1 lb or less per application;
- wait 4 to 6 weeks between applications;
- avoid over-fertilizing. It can burn or kill your grass;
- avoid fertilizing dormant grass.
The right conditions for fertilizing
Fertilizing during the growing season is key because that’s when your lawn can best absorb the nutrients. Cool-season grasses, which are what most Pennsylvanians have, grow best in air temperatures between 60 and 75. Zoysiagrass, a warm-season grass suitable for southern Pennsylvania, grows best when temperatures are between 75 and 90.
While temperature varies across the state, here are the average temperatures for the recommendation dates, so you can better understand why fertilizing during the recommended times is best practice.
| Cool-season grass application dates | Cool-season grass application date temperatures | Zoysiagrass application dates | Zoysiagrass application date temperatures |
| May | 70.5 degrees | April | 60.5 degrees |
| September | 73 degrees | June | 78.5 degrees |
| Early November | 57 degrees | August | 80.25 degrees |
For the most accurate recommendations on both fertilizer and amendments, get a soil test. Penn State offers soil fertility testing. Just bring a sample of your soil to your county extension office. You should get your results in two weeks.
For more Pennsylvania lawn care and landscaping advice
When to Dethatch Your Lawn in Pennsylvania
When to Stop Mowing Your Lawn in Pennsylvania
4 Best Grass Types for Pittsburgh
11 Spring Lawn Care Tips for Pittsburgh
Should I hire a professional?
Maintaining your lawn isn’t difficult, but it is hard work and time-consuming. Many lawnowners across the Keystone State are looking for help. But finding a trustworthy, affordable lawn care professional can seem impossible. Lawn Love can help. We have tons of vetted, reliable, local lawn pros who’ll leave your lawn looking luxurious without breaking a sweat or the bank.
Main Photo Credit: Zack Frank | Adobe Stock Free | License
