Is It Too Late To Fertilize My Lawn?

Fertilizing your lawn is a very important part of lawn maintenance. It helps ensure your grass is getting all of the nutrients it needs to be healthy and lush. However, you have to fertilize your lawn at very specific times in order to get the most bang for your buck. As the days get shorter and the weather turns colder this fall, you may be asking: is it too late to fertilize my lawn? Well, that depends on various factors.

In today’s article I’ll explain the basic rules you should be aware of and try to follow, and give you a simple plan you can stick to to achieve great results.

I’ll also let you know what you should (and shouldn’t) do right now in terms of fertilization – and list the specific local criteria you can use to determine if it’s too late for you to fertilize your lawn. It’s not a one-size-fits-all answer.

The right time to fertilize your lawn depends on what type of grass you have, including whether it’s a cool season or warm season grass. As a general rule, you’ll want to fertilize your lawn during periods of active growth. This is when each of the grass plants in your yard needs the nutrients most, and when the health of your lawn will benefit most from fertilization.

• Cool Season Grasses grow most during the spring and fall, when conditions are best-suited for those grass varieties, so the most important times of the year to fertilize these grasses is in the spring and the fall.
• Warm Season Grasses grow most during the heat of late spring and summer, so that’s the time of year you’ll want to fertilize and support their growth and health.

But, There’s More To It Than That…

With those general rules in mind, there’s still more nuance that you can pay attention to, and in order to maintain grass (and more pointedly soil) health.

There are specific nutrients you should provide at certain times of the year if you want a beautiful, resilient lawn that will actually be less work to maintain.

If you’d like a detailed and customized plan of what to do and when to do it for an amazing lawn in your growing zone, grab my free cheat sheet. It’s got everything you need to know and a done-for-you schedule and game-plan for a full season of DIY lawn care.

And in the meantime I’ve still got you covered right now with the answers you need.

The following article is a more detailed explanation on the best time to fertilize your lawn (and why). It also includes some of my best tips on how to properly fertilize your lawn, and the best seasons to do so.

Let’s start with the basics EVERYONE needs to know.

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Factors That Impact How Lawn Grasses Utilize Fertilizer

There are a few main factors which impact how grass in your lawn is able to utilize fertilizer.

I won’t cover all of them here, but briefly, these are two very important factors you absolutely need to pay attention to for good results:

• The Time of Year, and the Local Weather – Different types of lawn turfgrass thrive in different conditions, so understanding your grass zone, and the type of grass in your lawn will help you you understand the best times of year to fertilize your lawn (and when you shouldn’t). Beyond seasonal weather trends, your local weather plays a major role as well (think when rain is in the forecast, the weekly weather trends, and the time of day).
• Your Soil’s pH Level – The pH level of your soil plays a major role in the ability of your grass to uptake and utilize nutrients. I recently dug into a Lawnbright study on pH based on 2 years of customer soil test data that is an interesting read you should check out to learn more. One thing I learned was that if your soil pH is off the ideal by just one point, then 33% of your fertilizer may not be getting utilized by your grass at all.

So, Is It Too Late to Fertilize Right Now?

For most people, throwing down something with a lot of Nitrogen at this point in the year isn’t a great decision. It might be too cold to fertilize, but probably not for the reason you think.

Cool season lawns are still growing well at this time of year in many locations. But a heavy dose of Nitrogen may cause them to push a lot of new, tender growth that will get killed by a hard frost.

That said, you can absolutely offer your lawn something like a slow-release fertilizer that won’t lead to a big surge of growth, and if you do, I recommend that you look for something with a healthy dose of potassium – the last of the big three numbers (N-P-K) on the fertilizer bag.

Potassium is great during seasonal transitions because it supports overall plant health and can help plants manage dramatic swings in temperature (it’s helpful going into the heat of summer as well for this reason).

More About Weather Considerations

The weather affects how well your grass is able to absorb the nutrients it needs from fertilizer, so it’s very important to fertilize at the right time.

Most subscription lawn care plans include fertilizer products to apply to your lawn four times annually. The application dates are typically:

• Early Spring,
• Late Spring,
• Summer, and
• Fall

Just a few of the brands which recommend and build their lawn fertilizer lines and programs around this schedule include:

• Scotts,
• Milorganite,
• Jonathan Green,
• The Andersons,
• Lawnbox,
• Ace Hardware,
• and many more.

However, the right dates to fertilize your lawn depends upon the type of grass you have, and where you live.

Cool Season Lawns

Cool season lawns thrive in the cooler weather that’s present in the spring and fall. They’re referred to as “cool season” grasses because when the weather is cooler, there is more moisture in the air and the grass is able to grow better.

A few common cool season grasses include:

• Kentucky bluegrass
• Perennial Ryegrass
• Fine fescue
• Tall fescue

Cool season grasses are usually found in the northern parts of the United States, so if you live in states in that area, you likely have a cool season grass.

At a minimum, you should fertilize your cool-season lawn in the spring and fall.

Fertilizing Cool Season Lawns in Spring

For your spring application, I recommend that you break it up into early-spring, and late-spring fertilization.

In the early spring, try to also incorporate a pre-emergent herbicide – either as an additional application or as part of your fertilizer in a weed-and-feed formulation. This will help block germination of annual weeds in your lawn, so the nutrients you’re spreading feed the grass and not the weeds.

In the late spring, you’ll want to fortify your grass in advance of the summer, providing Nitrogen to sustain, and Potassium to protect against disease, heat, and drought.

I try not to fertilize my cool-season lawn in the summer, instead applying humic and fulvic acid and maybe biochar to help build soil health and make nutrients more accessible.

It’s too late to do your spring fertilizer applications if the weather is extremely hot.

As you transition to summer, irrigation (watering) becomes more important than fertilization for cool season lawns. Your cool-season grass will have the best chance of staying green in the summer if you give it at least half an inch of water twice a week.

Of course, you can skip the sprinklers if mother nature offers some rain.

Fertilizing Cool Season Lawns in Fall

In the early fall, you should aerate and overseed, fertilize, and apply an organic top dressing to your cool-season lawn (I use screened compost).

For best results, your fall fertilizer application should be at least six weeks before the expected first frost. Choose a fertilizer that is high in Nitrogen and Potassium – here are my favorites.

It may be too late to do your fall fertilization is it’s fewer than four weeks before the first frost.

Warm Season Lawns

Warm season lawns grow the best in warm and hot temperatures, and these tropical grasses are able to survive direct sunlight and intense humidity better than other varieties.

They hit peak-growth during late spring and early summer, and many go dormant once fall and winter hit.

The most common warm season grasses include:

• Centipede grass
• St. Augustine Grass
• Bermuda grass
• Zoysia grass
• Kikuyu grass

These grasses usually grow in the southern parts of the United States. If you live somewhere in that area, you likely have a warm season lawn.

As with cool season grasses, you should know what kind of warm season grass you have, as each grass will thrive with a tailored fertilization plan.

With a warm season grass, you should apply a high-nitrogen fertilizer in April. Around Easter, I recommend applying Milorganite to your lawn.

Milorganite adds organic matter to your lawn, which will give it extra nutrients and improve its ability to grow.

You should also do the majority of your warm season lawn maintenance in the summer, preferably early to mid May.

During the summer, you should apply Milorganite and an appropriate liquid fertilizer every few weeks.

You should also make sure that your lawn receives at least one inch of water each week, more in extreme heat.

The fall and winter seasons are the most difficult for warm season grasses, and they usually go dormant during this time, sometimes getting overseeded with ryegrass.

Apply a slow-release granular fertilizer in September, preferably during Memorial Day weekend.

In October, apply a fertilizer that is high in potassium, at least six weeks before the first frost hits your area.

In southern climates, if your first frost is expected in less than four weeks, then it’s probably too late to fertilize.

When To NOT Fertilize Your Lawn

Whether you have warm season or cool season grass, there are certain times you should avoid fertilizing your lawn.

A good rule of thumb to go by (no matter where you live) is that if it’s too cold, you should not fertilize your lawn.

The steps above for warm and cool season lawns mention applying fertilizer before the first frost hits in your area.

Frost occurs when there is a lot of moisture in the air and the temperature is low. The water, or dew, freezes on your grass and makes your lawn look slightly white.

Frost can prevent your grass from effectively absorbing the nutrients fertilizer provides, and it can also kill young, tender plant growth (even for hardy northern grasses that thrive in the cool-season growing zone).

Late November through December is usually when lawns start to frost over, though the exact timing depends upon your precise location (you can find the average date in your zip code here).

Final Thoughts: Is It Too Late to Fertilize My Lawn?

Try to make time in your schedule to fertilize your lawn at the right times of year.

Start off each season with a great spring lawn fertilizer application, and if you’re in a Nothern climate, end the year (at least 4-6 weeks in advance of your average first frost date) with an application of good fall lawn fertilizer which has a decent helping of potassium.

If you’re expecting a frost, you can still fertilize – but choose something that’s slow release like Milorganite.