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When fertilizer turns rock hard, just crush it back into shape. Source: clipground.com, http://www.moa.gov.jm & laidbackgardener.blog

You open a bag or container of fertilizer in the spring and you’re in for a shock: it’s as hard as a rock! It can’t be still good … but in fact, it is.

You may not have noticed, but there is no expiry date on most fertilizers. That’s because they’re made of minerals and the minerals don’t decompose … well, not over a normal human lifespan, at least. So, to turn your lump of fertilizer into something useable again, just crush it up with a hammer or some sort of pestle (a piece of wood, for example). It’s then good to go again.

Theoretically, liquid organic fertilizers could decompose and some manufacturers include do an expiry date: quite a long one, usually 8 to 10 years. In fact, though, if they decompose, they still only become simpler minerals that plants can use … and therefore, they remain useful.

Even so, some liquid fertilizers can settle over time and form deposits on the bottom or the sides of their container. If so, just shake them thoroughly to remix the deposits with the liquid.

Weed and Feeds

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Weed & feed products with chemical herbicides have been banned in most countries. Source: www.walmart.com.

The exception to the rule that there is no expiry date on fertilizers is “weed and feed” type fertilizer, that is, one that combines fertilizer and herbicide in the same product. Usually, these products have an expiry date of 3 or 4 years, but it’s the herbicide that loses its effectiveness, not the fertilizer.

Note that weed and feed products containing synthetic herbicides have been banned in most countries other than the United States. Only fertilizers that contain organic herbicides, usually corn gluten, remain on the market in Canada, Australia, and most of Europe. There is no expiry date on these. Just reduce these “organic weed and feeds” to powder if ever they harden.

Keeping Dry Fertilizers Dray

If dry fertilizers harden, it’s because they’ve come into contact with moisture. You can usually keep them dry and in top shape by storing them indoors in a dry spot over the winter.

Fertilizers left outdoors, in a tool shed, for example, can easily be affected by condensation as temperatures drop. To prevent this, attach a pack or two of silica gel to the inside of the container to absorb excess moisture.


Fertilizers: even if their structure changes, you can still use them, right to the very last molecule!20180304A clipground.com, www.moa.gov.jm & HC.jpg

Larry Hodgson is one of Canada’s best-known garden communicators. He has notably been editor-in-chief of HousePlant Magazine, Fleurs, Plantes et Jardins, À Fleur de Pot and Houseplant Forum magazines and is currently the garden correspondent for Le Soleil and radio garden commentator for CKIA-FM Radio. He has written for many garden publications in both the United States and Canada, including Canadian Gardening, Harrowsmith, Horticulture, Fine Gardening and Organic Gardening. He also speaks frequently to horticultural groups throughout Canada and the U.S. His book credits include The Garden Lover’s Guide to Canada, Complete Guide to Houseplants, Making the Most of Shade, Perennials for Every Purpose, Annuals for Every Purpose, and Houseplants for Dummies, as well as nearly 60 other titles in English and French. He is a past president of the Garden Writers Association (now Garden Communicators International) and the winner of the prestigious 2006 Garden Media Promoter Award offered by the Perennial Plant Association. He resides in Quebec City, Quebec, Canada.

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