Is fertilizer still good after it gets wet?

Fertilizer is a key component of healthy plant growth and crop yields. However, fertilizer that gets wet or damaged can lose its effectiveness. When fertilizer absorbs moisture, it can harden, clump, and become difficult to apply evenly. Wet fertilizer may also begin to chemically break down, altering its release of nutrients.

So is fertilizer still good after it gets wet? The answer depends on a few key factors:

How wet did the fertilizer get?

If fertilizer just got lightly damp on the surface but didn’t absorb a lot of water, it may still be fine to use. Allow it to fully dry out before application. But fertilizer that became soaked or submerged should be discarded and replaced.

What kind of fertilizer is it?

Some types of fertilizer handle moisture better than others. Granular and pellet fertilizers often hold up well to light moisture. Powdered or crystalline fertilizers are more prone to clumping and breaking down when wet.

How long has the fertilizer been wet?

The longer fertilizer remains wet, the more damage it will sustain. Fertilizer that dried out quickly may still be salvageable, while fertilizer left wet for days or weeks will almost certainly need to be replaced.

Was the fertilizer stored in its original packaging?

If wet fertilizer was in a sealed, waterproof bag or container, this provides some protection from moisture. But fertilizer in damaged or open packaging will have less protection.

How Moisture Affects Different Kinds of Fertilizer

To better understand moisture risks for fertilizer, let’s take a closer look at how some common types of fertilizer are impacted when wet:

Granular Fertilizer

Granular fertilizer consists of small pellets. It often contains protective coatings and binders to help the granules maintain their shape. This also provides some protection if granular fertilizer gets lightly damp. However, prolonged exposure to moisture can still cause granules to break down. Wet granular fertilizer is more prone to clumping and uneven application.

Powdered Fertilizer

Powdered or crystalline fertilizer is especially vulnerable when wet. The fine particles absorb moisture readily and can quickly clump together into a solid mass. Wet powdered fertilizers should not be used, as attempting to spread them will result in an uneven, clumpy application.

Liquid Fertilizer

Liquid fertilizers naturally contain high moisture. But if left uncovered or diluted with excess water, the nutrient balance can be thrown off. Always use liquid fertilizer as directed, and don’t try to apply if it has become excessively diluted.

Organic Fertilizer

Organic fertilizers like compost, manure, and bone meal are also very prone to moisture issues. Wet organic fertilizer decomposes rapidly, losing nutrients in the process. Prolonged wetness can make organic fertilizers unsuitable for application.

Signs That Fertilizer Has Been Damaged by Moisture

It’s not always immediately obvious if fertilizer has been compromised by getting wet. Here are some telltale signs to watch out for:

– Clumping or caking of powdered or granular fertilizer
– Crystals or pellets have softened or disintegrated
– Fertilizer has a rotten, musty, or moldy odor
– Evidence of moisture damage to packaging such as tears, water stains, or leakage
– Pooling of liquid or melted granules at bottom of container
– Growth of colorful algae, fungi, or bacteria colonies on fertilizer

If you observe any of these warning signs, the fertilizer should be discarded rather than risking a failed application.

Best Practices for Keeping Fertilizer Dry

The best way to avoid wet fertilizer issues is to take proactive steps to keep it dry:

– Store fertilizer in a sealed, waterproof container or bag. Keep the original packaging intact.
– Select indoor storage that is cool, dry, and free from leaks or condensation.
– For bulk fertilizer, use a covered bin or drum with a plastic liner.
– Avoid storing fertilizer directly on damp ground. Use pallets or shelving.
– Open fertilizer bags only as needed, then reseal tightly.
– Keep an absorbent material like sand or kitty litter on hand to soak up spills.
– If fertilizer does get wet, spread it out to dry immediately.

Taking these precautions will minimize moisture damage and maintain the nutritional integrity of your fertilizer.

Drying Out Damp Fertilizer

If fertilizer does become lightly moist or damp, all may not be lost. You may be able to salvage it by drying:

– Spread fertilizer out in a thin layer on a tarp, concrete floor, or other non-porous surface.
– Provide ample air circulation with fans or open windows.
– Use a dry, absorbent material such as sand, sawdust, or kitty litter to aid drying.
– Break up any clumps carefully to expose moist inner material.
– Check progress frequently and mix periodically to evenly dry.
– Once completely dry, run granular fertilizer through a sieve to remove fine particles.

Fertilizer that remains hardened or clumpy after drying should still be discarded. But with attention and care, lightly damp fertilizer can often be revitalized.

When to Replace Wet Fertilizer

Even with your best efforts, sometimes fertilizer gets too wet to salvage:

– Fertilizer that has become thoroughly soaked or submerged.
– Powdered or organic fertilizer that clumped into a solid mass.
– Fertilizer exposed to moisture for an extended period.
– Evidence of algae, mold, fungi, or bacteria growth.
– Strong odor or visible breakdown of materials.
– Packaging that is torn or compromised.

In these cases, the wisest option is to completely replace the fertilizer rather than trying to dry it out. The small upfront cost of new fertilizer is worth avoiding a failed application.

Alternative Uses for Wet Fertilizer

While wet fertilizer shouldn’t be applied as directed, it may still have uses around your home or garden:

– Use as mulch or a soil amendment in non-crop areas. It will break down slowly.
– Mix with compost piles to provide nutrients.
– Spread lightly atop grass in low-traffic areas away from plants.
– Pour liquid fertilizer in pond water to feed algae and microorganisms.

These alternative uses can allow you to salvage some value from fertilizer that otherwise would be fully discarded. But again, avoid applying soggy fertilizer directly to plants or crops.

Key Takeaways on Wet Fertilizer

To wrap up, here are the key points on whether fertilizer is still usable after getting wet:

– Fertilizer that is lightly damp may be okay if fully dried before applying.
– Prolonged moisture exposure and soaking damages fertilizer’s nutrient profile.
– Discard fertilizer that is clumpy, smelly, or moldy even if dried.
– Powdered and organic fertilizers are most vulnerable to wetness.
– Follow best practices for covered, indoor storage to keep fertilizer dry.
– Carefully drying and sieving lightly damp fertilizer may allow its use.
– Completely replace compromised fertilizer rather than risking a failed application.

With proper storage and quick action when needed, you can often avoid losing your fertilizer investment to moisture damage. But when in doubt, remember it’s better to be safe than sorry by starting fresh with new, dry fertilizer.

Frequently Asked Questions

Can I use old fertilizer that got rained on?

Fertilizer exposed to rain should be closely inspected. If the granules or powder became soaked and hardened, it should be discarded and replaced. But a light dampening from rain may be okay if allowed to fully dry before use.

What happens if liquid fertilizer gets watered down?

Excessive dilution of liquid fertilizer can reduce its nutrient concentration below the ideal level. Check the mixture ratio and if it has become overly diluted, discard and mix a new batch according to the package directions.

Can I reuse partially wet granular fertilizer if I sieve out the fine particles?

This approach is sometimes effective for salvaging lightly dampened granular fertilizer. Carefully break up any clumps and run the material through a fine mesh screen to remove degraded fines and dust. Fully dry the sieved fertilizer before use.

Should I be concerned about mold growing on damp fertilizer?

Yes, visible mold or fungi growth on wet fertilizer is a clear sign it should be discarded. The microbial activity will deplete nutrients, and the mold spores themselves can present health hazards. Any moldy fertilizer should not be applied.

How can I determine if fertilizer moisture damage is too severe to recondition it?

Signs like a strong rotten or musty odor, slimy texture, evidence of extensive caking/clumping, liquid pooling, or visible algae/mold indicate irreversible breakdown of the fertilizer. At this point, drying and sieving cannot salvage the material and it should be replaced.


Wet fertilizer may still be usable if the moisture exposure was mild and temporary. But prolonged wetness due to storage issues or rain can irreversibly alter fertilizer’s composition and effectiveness. Carefully inspect damp fertilizer for signs of clumping, odor, and visible microbial growth. Lightly moist material may be salvaged through drying and sieving. When the damage is more extensive, the only option is complete replacement. With proper handling and storage, you can minimize problems with wet fertilizer on your property or farm.

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