RealEstate Ke > Landscaping > Does Fertilizer Go Bad if Wet?

Does Fertilizer Go Bad if Wet?

Working on your landscaping and your hand hits a rock. You then realize that the bag of fertilizer you bought months ago is still sitting in a puddle of water from last night’s rain. 

Does this mean all of the fertilizer went bad? Not necessarily! You may still be able to use the fertilizer, but there are a few things I’ve included in this article that you should know.

I’ve noticed not so many people know that fertilizer gets more effective when it’s wet. 

When rain dissolves fertilizer into the soil, it releases its nutrients directly into the root zone, where grasses can absorb them. 

That’s why it’s safer to apply fertilizer after a rain rather than before.

Because of this, it is important to consider fertilizer application carefully before watering your plants.

I think it’s safe to say that the question of whether fertilizer can go bad comes up a lot, especially when you’re on a budget, time isn’t on your side, or you’re just looking to kill two birds with one stone (and save a few bucks in the process). 

Depending on where you live, if you can buy fertilizer at a big box store, chances are it costs less than if you buy it at a garden center.

Fertilizer is a blend of nitrogen, phosphorus and potassium. These three nutrients are vital to the health of your lawn and garden. 

The fertilizer works by feeding the soil so that the plants are able to absorb them. 

Fertilizer comes in many forms, including granules, liquids and dusts. Some fertilizers are slow release, and others are quick release. 

Regardless of the fertilizer you use, it is important to know that fertilizer does not go bad, if wet.

Nonetheless, it’s important to note that depending on the kind of fertilizer you have, environmental factors can play a role in affecting them in some way, at least from what I know. 

An organic fertilizer, for example, typically will not go bad if it’s wet, but it may lose some of its nutrients. 

Fertilizer that contains anhydrous ammonia or ammonium sulfate, on the other hand, can quickly degrade and lose some of its potency when it’s wet.

When I leave fertilizer outside, I usually notice that it starts to get slimy or smell bad, but it’s something I don’t worry about. The slime will eventually dry up and any gases that are released will dissipate.

But you may need to throw some of it away, especially if you’ve left it out for an unusually long time.

Some fertilizers contain organic materials that will decompose if left sitting for too long. 

This means that if your fertilizer gets wet, it can become ineffective. 

You can easily tell if your fertilizer is good or not by looking at the granules. If they are moist, or if they have become moldy or discolored, I’ve found them to be no longer good.

With that in mind, let’s see how we can store fertilizer in damp weather, and how to do it right.

How to store fertilizer in damp weather 

It’s the end of the season and you are storing your fertilizer away for next year. You’re all set to store it for a year, until the rain comes. 

There are some people who will tell you that storing fertilizer in a closed or damp area is a bad idea.

I’m not saying that they’re wrong.

But if that’s where you live? You need to know the best way to do it, right?

I mean, fertilizer can be a finicky product to store in the right conditions and can become ineffective easily if not stored properly.

A lot of homeowners tend to forget about storing fertilizer during rainy weather. 

Not only is the fertilizer more susceptible to getting wet, but it can also absorb water from the moist air, which can lead to chemical breakdown and even mold growth.

There are several ways that you can store fertilizer in damp weather, and each one is right, depending on the situation. 

The best way to store fertilizer in damp weather depends on whether you are storing it in a container or in a barn. 

  1. If you are storing it in a container, you have to make sure it is completely dry. If it is not dry, it will absorb water from the air and become less effective. 
  1. If you are storing it in a barn, you don’t have to worry about it drying out, but you have to make sure it is not exposed to water. You should make sure the barn has good ventilation, and you will also want to place a tarp under the barn to catch the leaks that may appear in the rainy season.
  1. Because of the potential for a reaction, store ammonium nitrate away from heat sources, electrical equipment, and flammable materials. Ammonium nitrate can be stored in any type of container, as long as the container is made of a material that can be tolerated by ammonium nitrate.

How to use fertilizer and weed killer in spring and fall

Fall and spring are busy times for lawn care: it’s when you apply fertilizer, weed-control products and spread mulch.

But before you do any of that, I like to make sure your lawn is green and lush—which means keeping an eye on it during the growing season. 

  • Warm-season vegetation has optimal growth during spring.

You should begin fertilizing your lawn in the spring and continue the second round in the fall after summer peak. Most grasses grow slowly until temperatures warm in the spring but will then grow rapidly. 

Actually, the general thumb of rule is that late spring is one of the best times of year to apply fertilizer to your lawn. The season when plants shift their focus from root development to start growing marks a natural transition to their annual growth cycle, and, as such, is an ideal time to apply fertilizer. 

Many homeowners believe that fall is the best time to fertilize, but this is actually not the case.

We expect weeds to be vulnerable during fall and so, a good time to kill off weeds and other pests that have found your lawn to be an ideal home, and to spike the lawn’s growth for the winter.

  • In cooler climates, fall fertilizing is beneficial for helping grasses through the winter. Before grasses go dormant during peak season, apply fertilizer heavily in fall and lightly in early spring.

If you don’t want to apply fertilizer at the recommended times, or if you need to catch up, you can use a timed-release fertilizer, which is available at home and garden centers.

One of the main things to look for when buying fertilizer is the percentage of nitrogen, the first number on a fertilizer package

Most lawn grasses need a fertilizer of about 1 or 2 pounds per 1000 square feet that’s rich in nitrogen to stay green and healthy all summer. 

But certainly, other plants might need a higher percentage of nitrogen. A good rule of thumb is to look for a fertilizer with a nitrogen content of 0.5 or 1.0 pound.


If you have stored fertilizer for longer than the recommended time, you may be wondering if it is still safe to use.

You can use a number of methods to determine if your fertilizer is still good, including visual inspection, smell, and touch, but the most accurate way to tell is to perform a chemical analysis.

Fertilizer doesn’t need to be stored in a freezer. You should be able to store your fertilizer inside a shed or garage. 

The key is to make sure it can’t get wet.

You can use a simple plastic container with a lid, as long as you leave it open partway and stack it on a piece of wood or cardboard so rainwater can’t get in.


Patton, A. (2013, May). Establishing a Lawn from Sod [PDF]. Lafayette, Indiana: Purdue University Cooperative Extension Service.

Zebedee Nambaleo
Zebedee Nambaleo

Zebedee is the founder of RealEstate Ke. He creates content by carefully examining and analyzing the real estate market, home improvement resources, and government data. His analysis is based on the principle of supplying high-quality, relevant, and in-depth information to his audience. By evaluating the current conditions and predicting future trends, he provides his audience with invaluable insights that allow them to make better decisions.