Quality fertilizer is not cheap, especially when you’re buying organic liquid fertilizers. Proper storage techniques will help you make the most out of that fertilizer year after year. But how long does fertilizer last? And what are the best ways to store it?
If properly stored, fertilizer does not expire. The minerals and elements will not break down. Synthetic granular fertilizer and dry organic fertilizer can last decades, synthetic liquid fertilizer can last between 8 to 10 years, and organic liquid fertilizer will last up to 5 years unopened.
The Shelf Life of Different Types of Fertilizer
Synthetic Dry/Granular Fertilizer
Granular fertilizers can last a pretty long time if kept dry, as the minerals won’t break down. If moisture gets in (like from high humidity), then it’ll turn into a gooey, unusable mess. Even if you dry it out and break it apart, it won’t be as soluble and the NPK ratio will be off. There’s no remedy for moisture and the only thing you can do is dispose of it following your local municipal guidelines.
If you have weed and feed (which is illegal in many regions), then it’ll only last 3 to 4 years. Weed and feed formulas aren’t effective, as the right time of the growing season to handle weeds and the right time to fertilize are very different. It’s more effective to fertilize on its proper schedule, and to target weeds rather than spray herbicide everywhere.
Synthetic Liquid Fertilizers
Liquid fertilizers can last 8 to 10 years when it’s kept in a shaded spot between 50F (10C) and 80F (27C). If it freezes, then it’s no longer good. Some minerals will be less soluble than before, changing the NPK ratios. The only thing you can do is dispose of it properly according to local and state regulations.
Organic Dry Fertilizers
Dry fertilizer (like compost, bone meal, and alfalfa meal) have a pretty long shelf-life so long as it’s kept dry. When you buy bagged compost, it’s heated, steamed, rinsed and dried, composted, and dehydrated before being packaged. That will stop the decomposition process. Once moisture is reintroduced, it will continue to decompose.
Home compost, like from a compost bin or vermicompost, will still be alive with microbiology that will continue to break down the organic material into usable nutrients. Store these for short periods in breathable containers.
Organic Liquid Fertilizers
Organic liquid fertilizers (like fish emulsions, liquid seabird or bat guano, and seaweed) can last 5 years or longer if the package is unopened and kept consistently at 70F (20C) and kept out of direct sun. Once you open the container, though, the shelf life will rapidly decrease as it’s exposed to air.
Don’t use it if it’s been frozen, there’s noticeable fungal growth, or it smells rancid. If the container has ballooned or a seam has broken because of off-gassing, it may still be usable if there’s none of the above.
To extend the life of the fertilizer as much as possible, don’t open the container until you’re ready to use it.
If you’re making compost teas, use them as soon as possible.
3 Storage Tips To Improve the Shelf Life of Fertilizer
#1 – Keep fertilizer dry, out of the sunlight, and above freezing.
In between use, store synthetic or bagged organic fertilizers in a shaded, dry spot where the temperature remains between 50F (10C) and 80F (27C).
Keep liquid fertilizers from freezing. Freezing temperatures can compromise the minerals’ solubility. The NPK value will not be what’s on the label. Don’t leave in an uninsulated shed or outdoors.
Keep synthetic granular fertilizers and bagged organic fertilizer dry. The key to extending the shelf life of granular fertilizers is to avoid high humidity. High amounts of moisture in the air will turn these fertilizers into a gooey mess. Once that happens, the solubility is compromised and the NPK will have changed. You can’t use it anymore.
#2 – Store out of reach of children and pets
If you have children and pets, store fertilizer out of reach. Synthetic fertilizers are toxic, and some organic fertilizers (like blood or bone meal) can be dangerous when inhaled or eaten. If you can’t store it up out of reach, store it in a metal or plastic container that they can’t open or bite through.
#3 – Pick the right container and seal it.
If you’re using fertilizers from a sealed container or bottle, keep the fertilizer in the container it came in, unless it’s damaged. That way, you keep all the useful information on the label. The bottle that liquid fertilizers come in extends the life of the fertilizer.
If the fertilizer comes in a bag and you’ve opened it (ideally neatly with scissors along the top), then roll over the top to protect the insides from dust and moisture, then place it in a larger container or plastic bag to seal it.
Living composts need to breathe, so store it in a plastic container with ventilation holes added. Label it with the type of compost and date you stored it. Don’t let it dry out completely.
When you know the right attribute to protect your fertilizer type, storing your fertilizer is pretty easy. If it’s dry/granular, keep it dry. If it’s living, give it ventilation. If it’s liquid, keep it from freezing. Do not use it if it’s been compromised and dispose of it safely. And keep them out of reach by children and pets. By taking these simple precautions, you’ll save money and get the most out of your investment.
Jamie is the founder of The Backyard Pros. When he was 15 years old he started working at a garden centre helping people buy plants, gardening products, and lawn care products. He has real estate experience and he is a home owner. Jamie loves backyard projects, refinishing furniture, and enjoys sharing his knowledge online.