When to Fertilize Your Lawn

Learn how, when and why to fertilize your lawn so that your lawn will be beautiful and lush this spring! The complete guide you need for your lawn.
Renee Lewis
Renee Lewis
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Last Update:
August 14, 2024

What is Lawn Fertilization?

Fertilizing is a vital part of good lawn care! Spreading these essential nutrients on your grass promotes healthy root growth, protects grass that has a lot of foot traffic, and helps with weed control like preventing crabgrass.

There are a couple different methods of fertilizer application. Homeowners can spread dry granular fertilizer or spray liquid fertilizer on your lawn, either way works. But remember, a healthy lawn requires fertilizer so make sure you fertilize regularly throughout the growing season!

Why Timing Matters

The time of year you fertilize matters. Generally the time to fertilize is when your grass is actively growing. To determine that, you need to know what type of grass you have, because there are two main categories of turfgrass and they require different fertilizing schedules.

There are warm season grasses that grow in areas like southern California, and cool season grasses, including Kentucky bluegrass, perennial ryegrass, fine fescue and tall fescue. They both have different growing seasons and require fertilizing at different times. There is a “transitional” zone between the warm season grass zone and cool season grass zone where you may find both types of grasses.

Cool season grasses grow in the spring and fall with their biggest growth seen in the fall. You will want to do a spring application of fertilizer and create a schedule to use the rest of the fertilizer before the summer heat kicks in and the cool season grass goes dormant. You can use either a slow-release fertilizer or a regular fertilizer. Fertilize again in the fall before it gets too cold.

Warm season grasses grow in the late spring and early summer. So fertilize using a slow-release or regular fertilizer during this time, and again after the highest heat of summer subsides. Start up your fertilization schedule again after the heat of summer but stop before it cools down for fall.

Seasonal Lawn Fertilization Guide

Spring Fertilization

Spring lawn fertilization

The best time for a spring application of fertilizer is right after the soil is consistently warm enough not to freeze, because fertilizer will not penetrate frozen soil. Look for green as a sign that the lawn has started growing. Root growth in many types of grasses is fastest during spring so fertilizing them is really important for a healthy lawn. Fertilize lightly in spring for cool season grasses, and more heavily for warm season grasses.

Nitrogen fertilizer is a good choice for a spring application, as well as traditional mulch which is organic and provides as much nitrogen as a typical store bought fertilizer. Mulch is when grass that is mowed is chopped up into really fine particles and left on top of your lawn.

Summer Fertilization

Cool season grasses need a break from fertilization during the summer heat and late summer. If you use slow-release fertilizers during spring, you want to make sure those will be used up before the summer heat.

For warm season grasses, their growing season is in mid and late summer so fertilize according to the schedule on the type of fertilizer you choose. Most homeowners choose to pause fertilization during the peak heat of summer no matter what type of grass you have.

Be careful not to over fertilize. If anything, err on the side of under fertilizing. Over-fertilization results in lawn burn. The grass can turn yellow and the ends of the grass can even become a bit crispy!

Fall Fertilization

The latest fertilization a warm season grass needs is in late summer. But for cool season grasses that remain slightly green throughout the winter, a fall fertilization schedule is important. Both grasses go into a type of winter dormancy during the cold months, but cool season grasses need a fall application of fertilizer. A specialized winterizing fertilizer is best!

Fertilize your lawn after the summer heat but well before the cold weather sets in so the fertilizer has a chance to set in and help protect the grass throughout the winter months.

Winter Considerations

There is no reason to fertilize your lawn in the winter when the grass is not growing. Oftentimes, the ground may freeze, and fertilizer cannot penetrate frozen soil anyway!

Winter is a time of rest and rejuvenation for the grass, so the fertilizer you applied at the end of summer or early fall is doing its work underground, keeping the roots healthy and preparing for spring.

Lawn Fertilization Based on Grass Type

Signs Your Lawn Needs Fertilization

Visible Signs of Nutrient Deficiency

If you notice your grass growing more slowly, or some of your lawn turning yellow, that may be a sign that it is time to fertilize. Another sign is if you start to see more weeds growing in your grass. These are signs that your grass has a nutrient deficiency and needs more of that nitrogen!

Soil Testing

Soil testing for lawn fertilization

If you are unsure of what type of fertilizer to use, or whether your lawn needs a specific fertilizer to meet a specific nutrient need, you should consider soil testing. Soil tests determine the nutrient needs of your lawn.

There are home testing kits you can do by yourself to determine the PH level of your soil and what type of fertilizer would be best to use on your lawn.

Choosing the Right Fertilizer

Types of Fertilizers

There may be a whole world of specialized fertilizers out there for specific lawn needs, but in general there are two categories: synthetic or organic fertilizers and both are usually aimed at increasing the levels of nitrogen, phosphorus and potassium in your lawn. The synthetic fertilizers you can buy at the store come in granular or liquid form. For the granular fertilizer, you can buy a hopper or a spreader to disperse the fertilizer over your lawn. For the liquid fertilizer, you can buy a sprayer to spray it over all your grass.

Organic fertilizer, as we discussed earlier, is typically mulch. Mulch is grass clippings that typically go into your lawn mower bag and that most homeowners throw away. However, if you mulch it - or chop it up into tiny pieces - you can reapply it to your lawn and it contains some key nutrients like nitrogen, phosphorus and potassium for your lawn.

Reading Fertilizer Labels

When you read the store bought fertilizer label you may see something called an N-P-K ratio. That refers to the three main nutrients lawns need that are found in fertilizers - nitrogen, phosphorus and potassium. A ratio of 3:1:2 or 4:1:2 is great for most warm season grasses and cool season grasses.

If your lawn has specific needs, select a fertilizer based on those needs. You can use the results of your home soil test to determine whether you need a special ratio of nutrients or whether the usual fertilizer will work just fine!

Frequently Asked Questions

When to fertilize your lawn FAQs

How often should I fertilize my lawn?

Cool-season grasses, including Kentucky bluegrass, perennial ryegrass, fine and tall fescue, should be fertilized right after they wake up from their winter dormancy and before the summer heat. This type of lawn should be fertilized again in the fall before winter.

Warm season grasses, also called southern grasses because that is where they are typically grown, are best fertilized in early spring and throughout mid and late summer. They will go dormant in fall so this type of grass does not need the fall fertilization like cool season grasses do.

Can I fertilize my lawn myself, or should I hire a professional?

Fertilizing your lawn is a DIY project that most homeowners can handle. You will need to know how many square feet your lawn is to estimate how much fertilizer you will need for the job. You can also choose whether or not you want to disperse the fertilizer on top of the soil or aerate the soil first. This allows the fertilizer to penetrate deeper into the soil faster.

However, if you have any concerns due to physical limitations or toxicity from the chemicals, there are professional services that you can call to do it for you. These services are especially popular in spring, to help homeowners get that beautiful spring green lawn!

What happens if I miss a fertilization schedule?

If you do not stick to your fertilization schedule as you planned, you can fertilize as soon as you remember. Just be sure to avoid fertilizing during the hottest part of the summer - especially for cool season grasses which will not be growing much during that time.

If you are late in late summer or fall, then just think about whether your grass is still going to be growing for a few weeks or not. If it is, then feel free to fertilize! For cool season grasses, you have a bit more time in the fall as that is when the lawn’s root system is doing a lot of root growth.

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