What Happens When Granular Fertilizer Gets Wet?

Granular fertilizer is a dry form of plant nutrition in small, spreadable granules. It can have different nutrient ratios to support plants in different stages, such as the 17-1-10 NPK ratio in our NutriPod grass plug fertilizer. This type of fertilizer is favored for its slow-release formulation—once applied to the soil, it gradually dissolves to provide sustained nutrients for plants over a long period.

How long you can store fertilizers depends on the fertilizer type you have. For example, granular fertilizers usually have a longer shelf life than liquid fertilizers, potentially lasting for years, even indefinitely, when stored properly. However, proper storage and keeping it dry is crucial as exposure to moisture can result in clumping or premature breakdown of granules, rendering them less effective. This highlights the importance of proper fertilizer storage to maximize potency.

How Moisture Affects Granular Fertilizer

Granular fertilizers have a protective coating that holds their shape and protects them from moisture. In slow-release fertilizers, this layer regulates the gradual release of nutrients, ensuring steady nourishment for plants.

However, prolonged exposure to moisture can break down this coating, which makes the fertilizer prone to clumping and uneven application.

Clumping: When moist, granular products tend to clump together, making it difficult to spread evenly. This clumping not only has the potential to clog mechanical spreaders but can also result in an uneven distribution of nutrients across your lawn, leading to uneven growth, color variations, and even damage in over-fertilized areas. Meanwhile, under-fertilized sections may experience stunted growth and lack vibrancy.

Nutrient Leaching: Because water activates granular fertilizer, exposure to moisture can trigger the dissolution and leaching of some nutrients from the granules. This can diminish its effectiveness, leading to a potential shortfall in delivering the intended quantity of nutrients.

Premature Release: Nutrient leaching also means the premature release of nutrients from slow-release fertilizer. Instead of a gradual and sustained delivery, the nutrients may be released immediately, potentially causing burning and damage to your grass.


Does Lawn Fertilizer Get Bad When Wet?

A brief exposure to moisture doesn't necessarily spoil lawn fertilizer. At a minimum, it can affect its application—wet, clumpy granules are difficult to spread evenly. It can also slightly decrease its nutrient content but shouldn't compromise overall effectiveness.

Unfortunately, prolonged exposure may degrade and even dissolve the fertilizer. Additionally, it can lead to mold growth, bug infestation, color change, a musty smell, altered texture, or a bulging bottle, which are signs your fertilizer is beyond usable.


Prevention and Storage: How to Properly Store Fertilizers

While some moisture will not immediately spoil your fertilizer, we advise storing it properly to prevent exposure to excess moisture. Below are a few tips for proper fertilizer storage, which apply to all types of fertilizer, whether in granular or liquid form.

Store in Airtight Containers

Store fertilizer in its original bag, and if the packaging is not resealable or has been opened, transfer it to an airtight, moisture-proof container. Fertilizers are hygroscopic, meaning they absorb moisture from the air, emphasizing the necessity of storing them in a tightly sealed plastic container to maintain efficacy.

Store in a Cool and Dry Place

Storing fertilizers in a cool, dry, well-ventilated place, away from direct sunlight, is essential. Excessive heat can compromise their efficacy and be as damaging as moisture. Additionally, ensure that these products are stored out of reach of children and pets to prevent any unintended exposure.

Avoid Contamination

Use measuring or spreading tools exclusively intended for your fertilizers to prevent contamination. Ensure these tools are kept dry before application. Additionally, make sure the fertilizers are stored separately from other chemicals and flammable materials, such as fuels or pesticides, as accidental mixing can result in harmful chemical reactions.



Different fertilizers last varying lengths of time. However, how fertilizers are stored significantly affects their shelf life. By keeping them in a cool, dry place, you can maximize their effectiveness and minimize waste.

NutriPod is a granular fertilizer for grass plugs. It is formulated to provide a gradual and steady supply of nutrients to help your new grass adapt and thrive in its new environment.

Shop for NutriPod on our website today.

The traditional methods of fertilizing plants can often be messy, inaccurate, and detrimental to the ecosystem.

Enter NutriPod®, a revolutionary solution that simplifies plant nutrition while being environmentally responsible.