Full of vinegar: Lee’s natural homemade weedkiller

Snow-in-summer (Cerastium tomentosum)

Oriental poppies, now in bloom with large, floppy, flaming-red blossoms, are worth oohing and aahing about. Likewise for snow-in-summer (Cerastium tomentosum), with small gray-green leaves and small white flowers, except that too few people know or grow this plant. Here, the two plants look especially congenial together, with snow-in-summer hugging the ground at the feet of the poppies and spilling over the rock wall that supports the bed in which these plants grow.

No skill is needed to grow snow-in-summer, or to propagate it. Plant it and it will spread, rooting as it creeps – but never with frightening speed.

Alas, the show from either plant is all too transient. Poppy foliage is soon to yellow and melt slowly back into the ground. And by the time you read this, blossoms of snow-in-summer will have tapered off and its leaves will have lost their exuberance of spring. The show’s transience makes it all the more appreciated.

A narrow yellow strip of vegetation – dead vegetation – sits at the bottom of the rock wall supporting the poppy and snow-in-summer bed (also home to espaliered pears, rugosa rose, alliums and other perennials) and at its upper border with the lawn. I can’t say that I’m proud of the yellowing strips of lawn and weeds, but the weedkiller that I applied is very effective at keeping errant weeds and grass out of beds, paths, from climbing the rock wall and growing in between bricks of my terrace and away from the bases of young trees.

Weedkiller?! Yes, I am spraying weedkiller – but the weedkiller that I’m spraying is very benign. I take straight household vinegar, which is five to six percent acetic acid, and add to it, per gallon, two tablespoons of canola oil and one tablespoon of dish detergent. The detergent and oil help the vinegar spread out on and stick to the leaves.

The USDA also has been researching the use of acetic acid as an organic spray to control weeds. It found 20 percent acetic acid to be very effective, which is not surprising. Twenty percent acetic acid, though, is neither very safe to use nor readily available.

My vinegar concoction, at five to six percent acetic acid, is, of course, not as effective as the USDA’s 20 percent. Nor is it nearly as effective as the widely used chemical weedkiller Roundup. My mix only kills green leaves; Roundup is translocated throughout a plant to kill roots, stems and leaves. Plants store energy in roots and stems, so can recover from my spray to grow new leaves. Eventually, with repeated spraying, vinegar-sprayed weeds run out of energy and die. Plus, my mix is not much different from salad dressing (except that it would need more oil, some herbs and no detergent).

My aim is to spray frequently enough to kill each emerging round of greenery while it’s still drawing on energy reserves, before the leaves start socking away excess energy in roots and stems. Early in the season, weekly sprays are needed; later, every two weeks or so.

Because vinegar only kills greenery by direct hit, it is most effective on smaller weeds where there is no “shadow effect.” The vinegar spray’s effectiveness drops at temperatures below 70 degrees Fahrenheit.

My farmden necessitates the application of about eight gallons of vinegar mix per session, most easily applied using a backpack sprayer. Mixing up and spraying the mix is no fun, but has become less unenjoyable with my new Jatco sprayer.

Anyone who has used a backpack sprayer will appreciate Jatco’s rather unique qualities: a carrying handle, clips for holding the pumping lever and spray wand during storage or carrying, a large mouth for easy filling and cleaning, a mixing paddle that moves with each pump of the handle and the totally internal pump that eliminates that awful sensation of spray material dripping down your lower back (even if it is just vinegar). The sprayer is almost perfect, two very minor shortcomings being the difficult-to-read volume indicator embossed on the tank and the lack of a bottom handle to grab when inverting the sprayer while cleaning it.

The best thing about the Jatco sprayer is the good leverage afforded by the way the pump handle is connected to the pump. Less pumping means less work. Carrying three or four gallons of liquid on your back in the hot sun is work enough.

Come visit my garden – and the garden of Teri Condon in Highland – on June 21 between 12 noon and 1 p.m. as part of the Open Days program of the Garden Conservancy. Admission costs $5. For more information, go to www.gardenconservancy.org/opendays/open-days-schedule/openday/884-ulster-county-open-day or call (888) 842-2442.

Any gardening questions? E-mail Lee at garden@leereich.com and he’ll try answering them directly or in his Almanac Weekly column. To read Lee’s previous “Gardener’s Notebook” columns, visit our Almanac Weekly website at www.HudsonValleyAlmanacWeekly.com. You can also visit Lee’s garden at www.leereich.blogspot.com.

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