When Should I Fertilize My Lawn?

I’ve been in the business of helping professionals manage natural grass surfaces for more than 40 years. These pros grow grass for a living — sports turf managers for high school, municipality, university and professional teams; golf course superintendents; and lawn care managers. Following the calendar is not the way to determine when and why to fertilize your lawn. Let’s take a refresher course.

Know Your Grass

There isn’t really a specific time period when everyone should start fertilizing their grass. Too many variables are at play for there to be a true “one-size-fits-all” answer. Essentially, grass should be fertilized only when it’s green and growing. Fertilizing too early in the spring or late in the fall can cause issues, be environmentally harmful and be wasteful. Here are some of the factors to consider as you concoct the best fertilization plan for your lawn:

• Geographic location: Do you live in a northern state or south of the Mason-Dixon Line?
• Length of growing season: This can be from 6 months to year-round.
• Types of grasses: Is your grass cool-season or warm-season?
• Types of soils: Are you growing sand in light, sandy soils or heavy, gumbo clay?
• Your quality expectations: Do you want your lawn to look like a golf course or a modest city park?

Best Time of Year to Fertilize

Again, your lawn isn’t on the clock. When you feed it during the season will depend on how many times during the year you intend to apply fertilizer and what the current weather conditions are. Generally, northern lawns can get by on two to three fertilizer applications per year and southern or southwestern lawns may need four to six.

If you’re applying fertilizer 4 times yearly, you can time your applications around the holidays.

1. Memorial Day (mid-to-end of May)
2. Independence Day (early to mid-July)
3. Labor Day (end of August to early September)
4. Halloween (more like early October, to be safe)

If you plan to fertilize 3 times, drop the Halloween application. If two times, remove the Independence Day application as well.

Do not fertilize if your lawn is suffering from drought or during a hot spell. Most likely, it’s gone dormant (asleep) and won’t absorb it anyway. Fertilizer applications should always be watered in. Time your applications just before a rainfall. Let Mother Nature help you. If you can irrigate your lawn, apply about a ½-inch of water within 24 hours after application. Wait to mow until after the fertilizer has been watered in.

Picking the Right Fertilizer

Consider having your soil tested before fertilizing in the spring. A basic soil test will reveal nutrient deficiencies and determine soil pH. Both are important factors when determining what fertilizer to use and when and how often to apply it.

Choosing the best fertilizer for your lawn will give you the most bang for your buck. Where you live will narrow your fertilizer choices. If you live in a phosphorus-free state or community, you’ll be using a zero-phos fertilizer. That means the middle number on the bag will be ‘0’, such as The Andersons Deep Green 24-0-11 or Pennington UltraGreen 30-0-4. Even if you don’t live in a zero-phos state, you should limit the amount of phosphorus you apply to your lawn. Phosphorus can run off the surface or leach through some soils, creating algae blooms in lakes, ponds and streams. This can drastically reduce water quality and limit the recreational use of these water features.

Use a lawn fertilizer that has at least 50% slow-release nitrogen. It will last longer and won’t leach and contaminate our precious water resources. Consider using a natural organic fertilizer like Safer Brand Lawn Restore Natural Fertilizer. It is generally more expensive but is gentler for the environment and helps build healthier soil. I’m a big fan. However, it can still be harmful if misused.

I’m not a big fan of liquid fertilizers, however. They don’t last as long as most quality granular ones and you’re limited to how much you can apply at once without causing turf burn. They may be cheaper to buy, but when you compare apples to apples, they’re more expensive to use.