Keep Dry Fertilizer Dry

Q. I have 50-pound sacks of 16-16-16 fertilizer in plastic bags. Somehow moisture got in the bags and the granules are wet enough that the fertilizer doesn’t drop through the spreader anymore. I live in a wet climate. What can I do to dry this fertilizer out?

Granular fertilizers like this Arizonas Best Citrus Fertilizer will last for years as long as it stays dry.

A. All sorts of scenarios are dancing through my head. Dry fertilizers in bags are meant to stay dry. If dry granular fertilizers stay dry, they are never hard to use. Getting wet is the one thing that can ruin a dry fertilizer specifically designed for use in spreaders that rely on some sort of a hopper (where you pour the dry fertilizer) for spreading it.

Fertilizer spreaders like this rotary spreader can handle a little bit of moisture in granular fertilizers, at least better than a drop spreader can. Its not as precise as a drop sgreader but can get the job done well if you are careful how you apply it.

Drop Spreaders are for Lawns

            Drop spreaders rely on specifically sized granules so it’s settings can be adjusted properly for a precise application rate. They are usually used for applying fertilizers to lawns. You have lost the drop spreader application option for that fertilizer. Chalk it up to “lessons learned” and buy a different bag of lawn fertilizer. This time get a “true” lawn fertilizer like a 21-7-14 and not 16-16-16. The “ideal” lawn fertilizer contains less phosphorus like 21–7–14 with half of its nitrogen (the first number) available in a slow release form.

Sometimes granular fertilizers are blended together with other fertilizers to get a fertilizer with the right numbers on the bag. Here is 21-0-0, aka, ammonium sulfate, which is 100% soluble in water. It has 21% nitrogen in the fertilizer bag. The rest is sulfur, hydrogen and oxygen (79%).

No Weed n Feed and Chunks

            As long as this fertilizer was not a “Weed N Feed”,  use it for other landscape plants, as a compost starter or even in a raised vegetable garden. In desert climates, spread the moist fertilizer out and use the sun to dry it. After drying, the fertilizer will dry into “chunks” that must be broken small enough to be used. Breaking it apart also creates some powder. You could still use a rotary spreader provided the fertilizer granules are dried and broken small enough to use its hopper or even apply it by hand. 

This 16-16-16 is a complete, all-purpose fertilizer with nitrogen, phosphorus and potassium. Use it once a season but no more than that because of the high phosphorus content.

Soluble Fertilizers Dissolve Quickly

            Fertilizers like 16–16–16 are made by mixing two or three fertilizers, with similar sized granules, together. The nitrogen granules in this fertilizer is probably the first to dissolve when it becomes moist . The dissolving of these nitrogen granules “glues” the other granules together into “chunks”. Breaking these chunks apart creates a white powder. You can use this powder to make a liquid fertilizer.

Another example of a lawn fertilizer because it has a low phosphorus content (middle number). It would be better if the last number, potassium, was a bit higher.

            Use no more than 1 to 1½ tablespoons of this powder dissolved in each gallon of water. This solution of water and fertilizer can be used to spray the leaves. This “liquid fertilizer” can also be poured safely on the soil very close to the plants. The remaining granular fertilizer can be used just like any 16-16-16 fertilizer. It won’t be 16-16-16 anymore but it will be a fertilizer probably high in phosphorus and potassium.

Traditionally water soluble fertilizers (intended to dissolve in water first) are made to be put in water but they should still be dry until they are used. This water soluble fertilizer made by Grow More is called "Super Bloomer" because it has a large amount of phosphorus (middle number) to promote flowering and rooting.

            Don’t throw this bag out. Use the fertilizer in it. It’s just going to take a little bit of work to get into a usable form.