The Best Fertilizers for Cool Season Lawns: A Complete Guide

As a homeowner, I know firsthand how challenging it can be to maintain a lush cool season lawn. Finding the best fertilizers for cool season lawns makes all the difference, especially with shorter growing seasons, cooler temperatures, and sometimes unpredictable weather.

Having the right fertilizer and lawn care routine is key. Let me share what I’ve learned from personal experience, along with actionable tips, to help you achieve a vibrant, healthy lawn.

Understanding Cool Season Lawns Challenges

Cool Season lawns face unique obstacles:

• Cooler Temperatures: Cool-season grasses thrive here but need extra care during the growing season.
• Short Growing Season: Timing is everything to improve your lawn’s health and growth.
• Soil Conditions: Varying soil types mean regular soil testing is critical to understanding your lawn’s needs.

The most common grass types for northern regions are cool-season grasses like Kentucky bluegrass, fescue, and ryegrass. 

These grasses flourish in the spring and fall but can struggle during summer heat. Fertilizing at the right times and using the right products can make all the difference.

My Personal Experience with Fertilizers

Over the years, I’ve experimented with a variety of fertilizers to find what works best for my lawn. 

Here are some of my top picks and lessons learned:

• Scotts Turf Builder Lawn Food: A solid, all-purpose fertilizer for general maintenance and greening. You can learn more about this product on the Scotts website. Reliable but not necessarily adjusted to every need. You can find Scotts products at most local garden stores or big box stores.
• Scotts Turf Builder Halts Crabgrass Preventer: While this combines fertilizer with crabgrass prevention, I’ve stopped using it. Fertilizing in early spring isn’t necessary because grass naturally surges after waking up. Instead, I use a standalone crabgrass preventer in mid-to-late April.
• Milorganite Slow-Release Fertilizer: A favorite for late spring (around Memorial Day). For additional details, visit the Milorganite website. Its slow-release formula feeds the lawn through early August, keeping it green and healthy during the early summer months. Like Scotts, Milorganite is easy to find at garden stores and big box retailers.
• Jonathan Green Fertilizers: My go-to for the best results. Learn their full range on the Jonathan Green website. Their Winter Survival Fall Lawn Fertilizer has been a game-changer, prepping my lawn for winter and making sure it bounces back strong in spring. Jonathan Green products are less commonly found in stores and are typically purchased online, either through their website or platforms like Amazon.
• Scotts Turf Builder WinterGuard Fall Lawn Fertilizer: Another good option for fall, helping strengthen roots for winter dormancy.

Fertilizer Comparison Chart

Fertilizer	Type	Best For	Coverage Area	Longevity	Where to Buy
Scotts Turf Builder Lawn Food	Synthetic	General maintenance	5,000 sq. ft.	6-8 weeks	Local garden stores, big box stores
Milorganite Slow-Release	Organic	Late spring through summer	2,500 sq. ft.	Up to 10 weeks	Local garden stores, big box stores
Jonathan Green Winter Survival	Synthetic	Preparing for winter	5,000 sq. ft.	6-8 weeks	Jonathan Green website, Amazon
Scotts Turf Builder WinterGuard	Synthetic	Strengthening fall roots	5,000 sq. ft.	6-8 weeks	Local garden stores, big box stores
Jonathan Green Organic Lawn Food	Organic	Eco-friendly lawn care	5,000 sq. ft.	8-10 weeks	Jonathan Green website, Amazon

Each of these products is budget-friendly, easy to use, and accessible for homeowners. 

However, when it comes to professional-grade products, things change. Many advanced fertilizers are not available for homeowner use, requiring specific certifications and licenses to purchase and apply. 

These products are also much more expensive and adjusted to professional landscapers.

Fertilizer Laws and Regulations

Lawn care isn’t just about picking the right products – it’s also important to follow your state’s fertilizer laws, which are designed to protect waterways from harmful runoff. 

Here are a few key considerations:

• Application Times: Fertilizer applications may be restricted during certain periods. For example, in my area of New Jersey, fertilizer cannot be applied to lawns between November 16 and February March 1, known as the fertilizer blackout period. Each state has different regulations, so it’s important to check your state’s rules, typically available on the Department of Environmental Protection website.
• Application Amounts: There are limits on how much nitrogen and phosphorus can be applied to lawns.
• Application Methods: Fertilizer should never be applied when the ground is frozen or saturated, during heavy rain, or immediately before a downpour. Avoid applying fertilizer to impervious surfaces like driveways or sidewalks to prevent runoff.

By following these regulations, you can protect the environment while keeping your lawn healthy.

More Information: Check the New Jersey Department of Environmental Protection for state-specific guidelines on fertilizer application.

When to Fertilize Cool Season Lawns

Timing is everything for cool season lawns. Here’s what has worked best for me:

Spring

• What I Do: Skip early spring fertilizing. Instead, apply crabgrass preventer in mid-to-late April. Then, in late spring (around Memorial Day), I use Milorganite for a slow-release boost that lasts through summer.
• Why: Early spring fertilizing can lead to excessive growth and fungus issues. Waiting until late spring balances growth without overwhelming the lawn.

If You Choose to Fertilize Early Spring – Do It Lightly

While I personally skip fertilizing in early spring – since grass naturally wakes up strong on its own – some homeowners still prefer giving their lawn a light push as it comes out of dormancy. If you’re one of them, go easy.

Start with a balanced fertilizer like a 16-0-10, 10-10-10, or even an 8-0-2. These are great for a soft, controlled green-up without pushing too much top growth. Think of it like spoon-feeding, you’re not forcing growth, just giving the lawn a little snack while it wakes up.

We’ve used Stay Green 16-0-10 in the past, which you can find at Lowes. Stay Green includes humic acid and kelp. It’s slow-release and works well across different grass types. If you’re using anything higher in nitrogen (like a 30-0-0), cut the dose in half. The heavier stuff is better saved for late April or May when soil temps are warmer.

Whichever product you go with, water it in well – or time your application with rain in the forecast to let nature do the work.

Again, this step isn’t required. But if you’ve got the itch to get out there early, a light feed like this can be a safe way to start the season.

Summer

• What I Do: Light fertilizing, if needed, in early summer using slow-release products. Focus on watering and mowing high.
• Why: Avoid stressing the grass during heat waves. Slow-release fertilizers provide consistent feeding without overloading.

Fall

• What I Do: This is the most critical fertilizing period. I typically apply fertilizer in early to mid-September, depending on whether we decide to overseed due to harsh summer weather. If overseeding, the strategy shifts to prioritize seed establishment.
• Why: Early fall applications strengthen roots and, when combined with overseeding, create a thick, resilient lawn for the next growing season.

Soil Testing Resources: Consider using the Rutgers Soil Testing Laboratory for accurate results before deciding on fertilizers.

If you’re overseeding this fall, learn the steps in How to Overseed Your Cool Season Lawn.

Start Simple Before Advancing

Before jumping into professional-grade lawn care products, I recommend starting with the basics. Products like Scotts, Milorganite, and Jonathan Green are affordable, effective, and easy to use. 

Once you gain more experience and confidence, you can consider more advanced options.

Advanced products often require specialized knowledge, certifications, and equipment, and mistakes with these can be costly. 

Start with simple, proven techniques to build a solid foundation for your lawn care journey.

If you’re considering overseeding your lawn this fall, check out our Ultimate Guide to Cool Season Lawn Care in Northern Climates for tips on preparing your yard.

My Evergreen Thoughts

Achieving a lush, green cool season lawn takes time, care, and the right tools. By focusing on proper timing, using quality fertilizers like Milorganite or Jonathan Green, and adhering to best practices and regulations, you can create a yard that thrives year-round.

Start by testing your soil and choosing the fertilizer that best suits your goals. With consistent care and a little patience, your lawn will become the envy of the neighborhood.

Think this is useful? Pin it to your board for easy access later! 👇