Pictured here is mainly a patch of Canada goldenrod that has expanded from one specimen that I rescued from a construction site year before last. I was sure that I had killed it with my less-than-skilled approach to transplanting. But Canada goldenrod is a vigorous plant. And it rapidly spawns numerous progeny.
Canada goldenrod is a “weed” in the best sense of the word. Let’s rethink weeds and weeding.
I’m starting to think that the smartest thing we can do in almost any landscape is to strategically choose our weeds and let them run riot. The alternative is to exercise too much control and squander the solar energy that would otherwise make plants grow and set the stage for life.
There’s a time to weed, but when we weed, are we contributing to biomass and biodiversity, or are we eroding biomass and biodiversity? I submit to you that most of our weeding reduces biomass and biodiversity. That’s why I choose to minimize weeding.
I weed when it’s absolutely necessary for aesthetic purposes. And I weed when the plant in questions threatens to dominate and thereby reduce biodiversity. Otherwise I let it grow.
The leaves of goldenrod support an impressive 105 species of caterpillars in my county, making goldenrod (solidago species) rank first among all “flowers and grasses” in the database of the National Wildlife Federation.
Also pictured here (the dark green in the bottom left) is ironweed. Its leaves support 22 species of caterpillars in my county.
This caterpillar food is vital to bird populations, because most songbirds need hundreds—if not thousands—of caterpillars to raise a single nest of chicks.
The diminutive Carolina chickadee requires 6,000-9,000 caterpillars to raise a single nest of young, according to Dr. Doug Tallamy, the famed ecologist and native plant expert.
The Virginia creeper pictured in the background is another “weed” in the best sense of the word. It grows wild in the eastern 2/3 of the US and Canada. You don’t need to plant it. It plants itself. It volunteers.
And Virginia creeper fills in spaces only a vine can fill, such as fences and tree trunks. But it will also crawl across the ground and serve as ground cover if you let it.
In my landscape Virginia creeper intermingles with common violets and jewelweed (aka, touch-me-not, impatiens), forming a tapestry of shade tolerant photosynthesizers that conserve water and pump carbon into the ground, enriching the soil for future generations of people and plants.
Virginia creeper supports 30 species of caterpillars in my county and ranks 48th on the list of 300 plants (ranked by genus) that support caterpillars in my county.
So if I want to support maximum biodiversity with minimal effort, I will pick a few native “weeds” and let them create a lush, green landscape that supports wildlife.
If goldenrod supports 105 species of caterpillars, ironweed supports 22 species, Virginia creeper supports 30 species, jewelweed supports 12 species and common violets support 28 species, that’s a lot of caterpillar food, which are in turn food for baby birds.
And then there are volunteer oak trees, maple trees, cherry trees, hackberry trees, walnuts, catalpas and mulberries, all of which have volunteered to grow in my yard.
I didn’t have to buy them, plant them or fertilize them. I only had to refrain from cutting them down.
And collectively, these trees support over 1000 species of caterpillars in my county. Oaks alone support 478 species of caterpillars and possibly twice that many other leaf eating insects, all of which does wonders for the food chain.
THE COOLING EFFECT OF PLANTS
If we can let plants grow then they will also cool our cities and home landscapes. Plants cool the air not just by casting shade but by emitting water vapor, in a process called transpiration.
Plants take the sun’s energy and use it to transpire countless gallons of water per day. Each gallon of water that evaporates creates a measurable, quantifiable cooling effect that feels like an air conditioner, as compared with a nearby treeless lawn.
When you have enough plant-rich landscapes, the rain falls more easily because the raindrops are not evaporating as they fall, which is what happens in countless places around the world, not because of an absence of water vapor in the sky, but because the air is too hot and dry to accommodate rain. By contrast, rain falls more easily into relatively cool, moist landscapes.
We can have more of these cool, moist landscapes worldwide by letting plants grow. This does not, by the way, preclude animal agriculture which, if done right, can give life to a landscape and its plant community. But it has to be done right. It’s usually not. Industrial crop farming also does needless harm, but could be done differently. Recommended reading: “Dirt to Soil” by Gabe Brown.
The changes I’m suggesting do not take a lot of time and effort. In fact we are making work for ourselves through mismanagement and the pursuit of dubious goals and a flawed vision. Nature will do much of the work that matters. Sometimes the trick is refraining from what need not be done, i.e., pulling a perfectly good “weed.”