If you purchased bulk supplies of herbicides, pesticides or adjuvants, it’s good to know the potential effects cold weather can have on it.

In general, freezing temperatures can change and negatively affect the chemistry of some pesticides inside the container and can also damage the container itself. Premixed liquid products that contain multiple active ingredients seem to be affected more by low temperatures than single-active-ingredient products.

Some premixes will separate in the container and can be difficult to get back into a homogeneous liquid before use in the spring.

Pesticides are best stored between 40 and 90 degrees F.

Many herbicides, especially new formulations, are not affected as much by low storage temperatures. Many labels — for example, atrazine, 2,4-D LV4, Acuron, Anthem Maxx, Corvus, metribuzin, Gramoxone 3.0, Sharpen, Enlist One, Valor, Osprey, Quelex, most dry herbicides and many others — have no minimum temperature limit, but simply state the product should be stored in its original container and in a dry, secure location.

Some labels stipulate the product should not be exposed to direct or extreme heat, or to sunlight. Other products — such as Liberty, Prowl H2O/EC, Halex GT, Pursuit, Reflex, Crossbow — have specific minimum temperature limits that range between 40 degrees and minus 10 degrees, depending on the product.

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There are a few products — like Prowl H2O, Engenia, Weedar 64 and others — that can be frozen and used once thawed. But make sure to warm the product for several days, and then shake it periodically and slowly. However, if the contents do not redissolve into a consistent mixture, it probably should not be used.

During this process, check the container for cracks by slowly inverting or rolling it on the ground. To be sure, read the storage and disposal section of the product label, which provides specific details about that product. Keep in mind that all these considerations are useful for adjuvant products, too.

Your intent should not be to stockpile products but to have a modest supply for use during the next growing season. Many herbicides, especially liquid products, typically don’t have a long shelf life, so make sure to keep your inventory fresh and don't purchase more than you can use within two to three years.

Dry products tend to last longer if properly stored, but their effectiveness still degrades over time. Also, when placing herbicides on storage shelves, make sure to put the dry products on the upper shelves in case the liquid products leak. This will help prevent potential contamination.

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Lastly, farm chemicals are expensive. It's a good idea not to draw attention to your full storehouse. Otherwise, you may find it not so full one morning.

For more details and many useful links, refer to the National Pesticide Information Center's webpage about other pesticide storage considerations.