Gardening

Plants Can’t Read Fertilizer Labels

Illustration of plant with glasses reading fertilizer label.

There is a wealth of fertilizers on the market, each claiming to be more extraordinary than the next, many specifically designed to suit a certain plant group from lawns to orchids, vegetables, cedars, roses, tomatoes and so much more. You therefore feel compelled to buy at least one box of each kind to satisfy your vast plant family. And you have therefore just been taken for a ride by the powerful fertilizer industry.

You see, plants can’t read fertilizer labels … and really don’t care which fertilizer you give them! So, if you feed lawn fertilizer to your roses or orchid fertilizer to your cedars, they’ll grow just fine!

Indeed, the importance of specific ratios of NPK (nitrogen-phosphorus-potassium) has been greatly exaggerated and often entirely invented. Sure enough, all plants* require the 3 major elements for healthy growth (and all the minor elements as well), but the exact proportion is of very little importance … so little, indeed, that you don’t even really need to take it seriously into consideration.

The most honest fertilizer on the market is all-purpose or multi-use fertilizer. It is aptly named, as it is suited to all plants*. But all those plant-specific fertilizers—the “dishonest” fertilizers as I like to call them—can also go on all plants.

My advice? When it’s time to fertilize, just grab the first fertilizer from your reserve and use it on all your plants, edible or ornamental, outdoor or indoor. When you run out, grab another one and use it up as well. When you just have no specific fertilizers left, buy an all-purpose fertilizer (because I feel one should reward honesty in packaging) or a fertilizer which does not refer explicitly to a type of plant: seaweed fertilizer, fish emulsion, blood meal, etc. The latter fertilizers, by the very fact that they make no claim to a specific use, are also all-purpose and therefore “honest”.

Personally, I always opt for organic fertilizer, because most organic fertilizers are complete ones and contain the full range of major and mineral minerals, but that’s a story in itself: one to cover in a future blog!


* Carnivorous plants are exceptions to the “all-purpose fertilizer suit all plants” rule: most don’t need any fertilizer at all!

Article originally published in this blog on September 9, 2015

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.

5 comments on “Plants Can’t Read Fertilizer Labels

  1. Does this apply to succulents/desert plants as well? I’m constantly seeing warnings not to use high-nitrogen fertilizers on succulents as they apparently cause malformed growth and/or etiolation.

    • Just reduce the amount of fertilizer: most fertilizers are too concentrated for succulents anyway. By diluting them (I usually cut by 4 or 8), any risk is removed.

  2. I love the heated discussions between gardeners about the ‘blue’ fertilizer. Pretty funny.

  3. We do formulate and use specialized fertilizer in production nurseries, but only to avoid wasting what particular crops do not need much of. Also, in some situations (such as the Santa Clara Valley) palm fertilizer helps queen palms that want more manganese and magnesium. Those nutrients are not often deficient, so are not so important in fertilizer.

    • Of course, it does not happen often, an is not repeated much. A minor adjustment lasts a long time. Queen palms grow like weeds anyway.

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