If I’ve learned one lesson about having a flower garden, it’s about feeding the plants.
The penny finally dropped when I was admiring some marvelous hanging baskets that were simply overflowing with blooms and the owner said she simply watered them with 20-20-20 liquid fertilizer once a week.
A decade ago, the first year I filled a front flower bed with geraniums, I didn’t think about feeding. I was delighted with the big, bold red geraniums that were my first effort. But by midsummer, the blooms just stopped coming and I simply couldn’t figure out why.
With hindsight, I can see that the soil in that bed had probably been planted with flowers every summer for decades. Perhaps previous owners had replenished the soil periodically: I certainly hadn’t. There were simply no nutrients left in it to keep plants going.
Flowering plants — especially the short-lived annuals that seem to flower with almost frantic abandon all summer long — are voracious users of soil nutrients. When you look at the amazing growth of plants roots, stems, leaves and flowers over the summer, think of what fuel it must take to drive that plant’s “engine”.
So we have to make sure that our plants have enough to eat. Malnourished plants will not thrive and, eventually, will sicken and die just as a starved human being would.
Many organic-thinking gardeners rely on the adage: “Feed the soil, not the plant.” And there is more to that saying than just playing with words. Gardens planted in rich, loose soil that contains naturally-occurring nutrients will always do better, in the short term and the long term, than gardens where granular or liquid fertilizers try to compensate for compacted, tired soil.
You can enrich your soil by adding compost or well-rotted manure. And you should.
But let’s face facts: you’ll need to dig in a great deal of compost — a layer at least two inches thick across the entire bed — or use many wheelbarrows of manure to adequately feed a thriving flower bed.
Some gardeners — retired people or those without a young family taking a lot of time — are able to use soil amendments like manure and compost in adequate amounts.
I have added six cubic yards of manured topsoil to my flower beds in the last year-and-a-bit. And I add some compost to my beds every spring and summer, but my region-supplied Soil Saver doesn’t give me anywhere near enough for a two-inch layer. And even though I’m lucky enough to be able to lay my hands (so to speak) on well-rotted manure, I don’t get around to picking up very much of it.
When time is the thing we seem to have the least of, sheer convenience can make the difference between doing a job regularly and not doing it. I have ended up this spring and summer doing much of my gardening between 6.15 and 8 a.m.
So, to make sure my plants get fed and bloom their best, and to try to coak second blooms out of perennials, I have resorted — without a shred of guilt — to a synthetic fertilizer.
Once a week, I screw on the hose-end sprayer and soak my flower beds with a water-soluble fertilizer. I use whatever I have handy that has a fairly evenly balanced N,P,K ratio: 15-30-15, 20-20-20 or anything similar.
(A word on those numbers. They stand for, in order, the percentages of the three major plant nutrients: nitrogen, phosphorus and potassium, also known by their chemical symbols of N, P and K. They boost, again in order, leaf growth, root growth and flower growth. A mnemonic phrase to remember the right order [I found it in The Reluctant Gardener, published by Random House], is the phrase Little Red Flowers — Leaf-Root-Flowers. To “green up” a lawn or help a plant with yellowing flowers, you would use a high-nitrogen fertilizer like 20-5-5. To coax more blooms out of a lazy annual, try 5-5-20.)
Organic equivalents include watering with manure tea — made by steeping a cloth or burlap bag of manure in water for several days — or using a fish-emulsion fertilizer. Despite promises of no odor, I found my band-name fish emulsion fertilizer left a distinctive smell behind for several days and the next time it rained. My wife said it reeked.
Granular fertilizers break down more slowly and so will last longer. Look for N-P-K ratios of about 6-9-6 or 7-7-7. Generally speaking, you need only apply twice in a season — late spring and mid summer. Most will go on at the rate of about a handful to a square metre or yard — what garden writer Trevor Cole describes as “enough to see that you have put fertilizer on, not so much it looks as though it had snowed.”
(A column from 1995.)