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To “P” or Not To “P”
by Dan Clost
by Dan Clost


First serious garden earned 25 cents from the Kemptville Horticultural Society when I was 12. Have been poor in horticulture ever since but rich in spirit.

Went to work writing the Good Earth column (over 500 articles published in newspaper, magazine, website and journal.) and learned that what was printed wasn't what I wanted to say and certainly not what Gentle Reader understood me to say. Subsequently have developed a certain clarity and economy of words.

Day job- nursery and production manager for a large nursery/garden centre
Side job- Garden restoration and renovations, design consultations, remedial pruning.
Night job- garden writer and communicator (overnight success in another 20 years)

Dan gardens in Canadian Zone 5b

November 25, 2012

That is a good question, Gentle Reader. “P” in this gardening column stands for “phosphorus.” Phosphorus has become the shunned element in the grand world of Big Brother watchdog-dom. Let me make a distinction here: there are those amongst the cadre of horticultural professionals who caution us that sometimes we don’t need to use phosphorus. That is both prudent and correct. However, there is a gaggle of strident, clamouring hounds who take up the call of whatever is deemed to be bad for the planet, seldom referring to any form of test or study, calling for its complete ban. If they could impose such a ban retroactively, they would.

Their knowledge source is often a special interest magazine or choice number 43 on a Google search. The distinction of correct or incorrect is quickly lost in emotional posturing that muddies the waters of rational discourse. So why this wee diatribe? I don’t want you to subconsciously lump the anti-P forces in with that group and stop listening to them.

Soapbox digression: of all the items that are “bad” for this planet, might I suggest that us human types are probably the “baddest.” Saving the Planet means, to cynical me, keeping the world habitable for humans. Mother Earth will do just fine without us and if we continue to abuse and poison what we are privileged to enjoy, Gaia will have a little hiccup, humankind will disappear, and life will continue on its way. We’ve had our share of “tickles” with things like DDT, salinization of irrigated crop land, and even nuclear powerplant mishaps.

Frankly, I sort of like being on this planet and I would prefer to do so for some time to come. That means taking care to not mess up the delicate balance that is already teetering on the brink. Is phosphorus the next item on the list that will induce a cleansing cough?

Phosphorus is an interesting element described as a “non-metal”. You’ll find that on page one, item one of a Google search. It is really, really important for life. Trouble arises when we not only use P indiscriminately but when we don’t follow the process to its logical conclusion; that being where it ends up after we’re done with it. It is one of the most important pollutants in our waters. GR, “our waters” isn’t a nebulous phrase referring to somewhere like Pittsburgh or even the Sydney Tar Ponds. I’m referring to the Bay of Quinte which has been identified as an Area of Concern where human activity has had a severe and deleterious affect on the water. To find out how bad it was, to speak to the people who are doing something about it and to learn what you can do, contact the folks at the Bay of Quinte Remedial Action Plan. Their website is; telephone at 613-394-3915. You can come into our store, and many other locations in the area, to pick up pamphlets and other info.

They are not clamouring hounds although they are passionate about their work and they have done some marvellous work. Next time you see one of them, say “Thank you.” So what can we as gardeners do to reduce phosphorus run-off? Get a soil test done. Learn what your piece of this good earth has to offer. Generally, we have an abundance of most nutrients, especially phosphorus, in the EMC cachement. Diagnosing a deficiency is not an easy matter- in fact the most distinguishing characteristic is that the plants are smaller than they should be.

Actually, it is easier to diagnose the effects of a surplus of P- plants will show zinc and iron deficiencies and acidic based plants will not thrive in the basic soil conditions that too much P can cause. If you discover that you do, indeed, have a sufficiency of P, make the decision to stop buying it. As stewards of our estates, we will soon be using a lot of fall lawn fertiliser. Buy one with a zero P rating; look for fertilisers with numbers like 32-0-10 and 21-0-5.

Those numbers are “the big 3” and are prominently listed on each bag, jar or box of fertiliser sold. In order the numbers represent the amount of three nutrients N-P-K, nitrogen, phosphorus, potassium available to the plant on a percentage basis. Those numbers are from what I believe are the two most represented brands in our area, Scott’s and CIL.

I do have a question though. How come a fertiliser which no longer contains an ingredient is just as expensive as the one that does?

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