This time of year typically marks the beginning of summer’s hottest weather, a season when the growth of all our desirable plants — our carefully nurtured flowers and shrubs — stalls, and only the weeds seem to flourish unabated. This is more than annoying and unsightly. Weeds are masters at competing for resources. In particular, their roots are extremely effective at tapping the moisture in the soil, depriving their more desirable neighbors of what is often a scarce resource in summertime. This is especially harmful because plants typically need extra moisture in hot weather, so that they can evaporate it off the surface of their leaves and cool themselves. The solution is obvious, right? Rip those weeds out, roots and all! Actually, according to Larry Weaner, that is most often a mistake.
Who is Larry Weaner? He’s the founder of Larry Weaner Landscape Associates, one of the nation’s leading ecological landscape design firms. I got to know Larry when I co-authored a book with him about his style of gardening some years ago. Larry has a background in traditional gardening; besides on-the-job training with various landscaping companies, he studied ornamental horticulture at what is now Pennsylvania College of Technology. However, he has added to and emended what he learned in that way with years of study of landscape ecology and experimenting with ecological principles in action. In light of that study and his 40-plus years of experience in the field, he now holds, as he told me the other day, that pulling weeds—especially roots and all—is counterproductive.
The reason behind this position is that weeds are commonly symptoms of landscape disturbance. When a gap is opened up somehow by the death or removal of a plant, very often it is a weed seed in the soil that sprouts first so that it can take advantage of, and fill, the hole. Disturbance of the soil is particularly effective in prompting weed growth. If you still use a rototiller in your vegetable garden, you know how that disturbance of the soil raises a flock of new weed seedlings. On a smaller scale, ripping a weed out of the ground also disturbs that soil and is likely to provoke more weed growth.
That’s why, except in the case of the most pernicious and aggressive weeds, if an area contains significant amounts of desirable plants, Larry Weaner recommends reaching down and snipping weeds off at the base rather than pulling them. Decapitating the weed prevents it from setting seed, which in most cases stops its reproduction. It also weakens the weed and gives an advantage to the growth of nearby desirable plants, so that eventually, perhaps with a subsequent repetition of the snip, the weed is squeezed out. Snipping is quicker and easier than uprooting as well, which turns weeding into a less burdensome task.
Consistency in keeping weeds from setting seed can eventually pay big dividends. There are, in any given area of soil, large numbers of seeds lying dormant in the top few inches of the soil. This is what ecologists refer to as the “seed bank,” and as I mentioned above, the bulk of it is commonly weed seeds. If, however, you consistently frustrate the growth of weeds while letting more desirable plants go to seed, you can alter this balance. If you do, when a disturbance does infrequently occur — when a squirrel digs a hole, say — what is more likely to shoot up is some desirable plant. Such a situation makes for a garden that requires far less maintenance. This treatment is especially effective if you have been planting native species, plants that are naturally adapted to the area. If you succeed in filling the landscape and seed bank with them, you have created a landscape that can remain largely self-sufficient for a long time.
If you are interested in listening to the rest of my conversation with Larry Weaner, I suggest you go to my website, www.thomaschristophergardens.com, and click on “podcast.”
Be-a-Better-Gardener is a community service of Berkshire Botanical Garden, located in Stockbridge, MA. Its mission, to provide knowledge of gardening and the environment through a diverse range of classes and programs, informs and inspires thousands of students and visitors each year. Thomas Christopher is a volunteer at Berkshire Botanical Garden and is the author or co-author of more than a dozen books, including Nature into Art and The Gardens of Wave Hill (Timber Press, 2019). Be-a-Better Gardener is syndicated in 19 print and online publications, reaching 250,000 readers. Tom’s companion broadcast to this column, Growing Greener, streams on WESUFM.org, Pacifica Radio and NPR and is available at his website, https://www.thomaschristophergardens.com/podcast.