It’s all about the pH

  • Published in MyView

By Mimi Clark

Forty-four years ago, I was a young bride on the Maynard farm in Moretown. The social outing I looked forward to most back then was the Farm Show in Barre. I wasn’t interested in the big tractors or other heavy equipment nor the animals, but I was inexplicably drawn to the soil. That year at the farm show, my expectations were more than met with a brochure from the New York Lime Association. In their glossy pamphlet was what I needed to know to transform the clay subsoil behind our house where I was to work wonders and create a lush prolific vegetable garden.

The black, shiny pages of the article taught me about fertilizer availability, specifically nitrogen, particle aeration and the proper pH. I became convinced that the only way to obtain favorable results growing most plants was to use limestone powder to make up for what the average Vermont soil lacked. The article explained that the limestone particle was the only one that could wedge itself between clay particles and loosen the otherwise flat platelets that stacked on top of each other excluding oxygen. The lime particle helped to release nutrients locked in because of the acidity. I was an instant believer.

According to Random House, pH is the chemical symbol for the logarithm of the reciprocal of hydrogen ion concentration in gram atoms per liter. Fear not, what one needs to know is just the desired number for a plant or location on this critical scale that goes from 1 to 14. Most plants favor and grow in a range of 5 to 8 with 7 being neutral. Anything below 7 is acidic; anything above is alkaline. I memorized the charts in Rodale’s Organic Encyclopedia pertaining to each vegetable and flowering plant’s pH and began having results in my garden that few people have had in Vermont. My father-in-law, a third-generation dairy farmer from Warren, was skeptical at first but later began to praise me because in a dozen years I did what would have taken a thousand years naturally which was a huge exaggeration, but I accepted the compliment.

Years later, in the “S” turns of Moretown, I was to have my favorite garden on the Mad River surrounded by monolithic stones and guardrail borders out front on the road with the topsoil being the salt and sand that the plow trucks added every winter and the tons of organic matter that I contributed. I had learned many years before that there are 20,000 particles of clay to one in a sandy soil. The first time back on the farm I ordered soil tests, the results came back nonspecific to either soil type so I learned to pioneer my own weights and measures considering lime and pH. I limed my sandy borders spring and fall and grew 75 roses from many of the 16 classifications. I learned a few secrets to their hardiness in our cold country and one was to keep the pH high or slightly under neutral; so although I had salt and sand and less than three-quarters of a day of sunlight, I was able to make up for what lacked by keeping the pH high, around 6.8, which is what most vegetables favor as well and I was thrilled with the success. One year, I was obsessed with a plant named omphalodes verna. It was a beautiful light periwinkle star-studded ground-hugging slow creeper I had ordered from the Kentucky Appalachians. Before the flood of 1998 when I lost a sizable chunk of land behind the house, there were deep pockets of humus that were acidic and perfect for my new addition. It sat there all summer and did nothing. In desperation, I decided to put it out front in a guardrail garden and the craziest thing happened; the plant became rampageous. It quadrupled itself daily and I ripped it out shortly after. But the lesson here was huge! I saw firsthand how a seemingly “native” plant could turn into a monster given conditions other than its own habitat, a radical change in pH!

I didn’t have any knotweed on my riverfront property yet, but I was getting nervous after making the discovery about the plant from Kentucky. At that time, I had no bishop’s weed either but started to wonder if there were ways to play with the pH to alter existing conditions that would make them unfavorable for invasive plants, without harming the environment and actually bringing it back to its more original state. Why couldn’t it work both ways?

I learned that east of the Continental Divide in the U.S., the soils are for the most part acidic. West, they are alkaline or the higher end of neutral 7 on the pH scale. Acid rain from the Midwest had long since been showering down more acidity on Vermont. I began to speculate that all of this activity was pulling the pH of the soil down making it more favorable to the knotweed. I looked online at the Friends of the Mad River site and found that they listed the favorable pH range of knotweed to be 4 to 7. So, what would happen if I brought the pH up on my property close to neutral, which is what I had been doing all along? I reasoned that dairy farmers have been liming their fields up The Valley for a long time as they know that alfalfa and corn won’t grow if the pH isn’t high enough and that Vermont soils are deplete of calcium and magnesium, two other nutrients in Dolomitic limestone. There was no discussion about pH at the Friends’ site. The risks of liming and altering the river favorably or unfavorably had not been explored. I knew that the lime particle was very heavy and by nature of gravity sank deeply, quickly reaching down where the roots of the knotweed ran. I had also memorized a list of plants that are lime haters or calcifuges and found none that grew locally.

Experiments along the river impact the entire river and must be handled with extreme care. I would like to be involved with other experts in the field in designing such research as all of my results have proven positive. Why aren’t I rich and famous? Because I’ve never written anything down, never officially documented what I have done. I was content to grow enormous poppies on the pavement for the sheer pleasure of it. I feel the call to make my knowledge known; my science has been evident to all of you who have passed my gardens. There is a greater cause at hand. The film Hidden Figures about the three African-American ladies who saved the space program to the moon inspired me to speak up, to have the confidence in what I know and to say that there is a solution to invasive plants readily at hand, just waiting to be acknowledged and discovered. It might look like a combination of hacking, Roundup and limestone.

Mimi Clark lives in Moretown.