By Susan Tweit, Houzz
Do you hate to weed? Love to weed? Are you confused about what’s a weed and what’s not? Weeding may not be what most excites us about gardening, but it is an integral part of the practice of bringing beauty to our nearby spaces, and restoring nature and our connection to it.
Practice involves the sense of something continual, something that when done mindfully yields rewards beyond the immediate task. These simple tips on why, what and how to weed will inform and inspire your gardening practice, and help improve your landscape and your relationship with it.
Why weed? Aren’t all plants good? Hardly, as the shelves of herbicides, both synthetic and natural, at any garden center demonstrate. Gardeners put a lot of energy into “editing” our landscapes to include the plants we want and to remove the ones we don’t.
How do we know which is which? That depends on our definition of a weed. The simplest is “a plant in the wrong place,” where “wrong” is subjective and dependent on personal taste. A more nuanced definition is ecological: A weed is a disrupter of ecosystems, an organism that doesn’t cooperate and play well with others, making life harder for all and upsetting the balances that keep natural and garden communities healthy.
The kudzu vine shown here, native to tropical Asia, is an example of a disrupter of ecosystems. This vine in the pea family flourishes so aggressively that it can smother buildings and large areas of landscape, including whole trees.
Knowing Your Weeds
The most important part of making weeding as painless as possible is knowing weeds at all stages of their life cycle, from seedling to seed. For help learning your weeds, you can take master gardener classes or find information at your local extension office or online.
The gray-green and fuzzy seedlings of Kochia scoparia (Bassia scoparia) in this photo, for instance, look nothing like the adult plants, which get as tall as 6 feet, and are pyramid-shaped with red stems, linear leaves and tiny green flowers that emit clouds of yellow and very allergenic pollen when the plant is touched.
Kochia, a native to the dry parts of Asia, is a serious invasive weed on disturbed soils in wild lands, agricultural areas, parks and gardens throughout the arid West. Knowing that the fuzzy blanket of cute seedlings will grow into the difficult-to-manage adults, with their ability to produce tens of thousands of seeds per plant and to break off at the base and blow about, releasing seeds as they go, is key to knowing how to deal with these annual weeds. (See tips in the following section about annuals and biennials.)
Susan J Tweit, original photo on Houzz
Annuals and biennials. Dealing with annual or biennial weeds like kochia, or the cheatgrass (Bromus tectorum) shown here, is very different from dealing with perennial weeds.
Annuals go through their whole life cycle in one growing season — sprouting, elongating into an adult plant, flowering and producing seeds. Biennials follow the same plan, only they devote one year to growing and storing energy, and the next to flowering and producing seeds.
Annuals and biennials invest most of their energy into producing aboveground parts, growing, flowering and producing massive quantities of seeds, and their root structure is relatively weak. Weeding is most effective when they’re small and haven’t flowered yet. At that stage, they can often simply be pulled, hoed up or mowed.
The point is to prevent these plants from seeding, since the parent plant will die anyway. Mowing or spraying them after they have begun to seed will only make the problem worse by stimulating them to produce more seeds (spraying) and spreading the seeds more widely (mowing).
Perennials. Many plants that are toughest to kill are perennials, because they store so much of their biomass belowground, where it is harder to reach, and they can sprout from their roots. The thickened taproot of houndstongue or gypsy flower (Cynoglossum officinale) in this photo is a great example. The plant dies back to that taproot in winter and springs up again the following season(s), drawing on its stored energy.
Successfully eradicating perennials means not just cutting off the top, but also killing the roots. You can cut back a thicket of Japanese honeysuckle (Lonicera japonica) or Himalayan blackberry (Rubus armeniacus), for example, and the following spring, the vines will grow back thicker than ever, fed by those underground food stores.
Knowing that you’re dealing with a perennial weed changes your options: You have to kill the roots, tubers or bulbs that keep the aboveground plant coming back year after year. That means digging it up wholesale, poisoning the roots (whether with a natural herbicide or a synthetic one), or repeatedly killing or cutting back the top until the roots are exhausted.
Space-hog weeds. Some weeds succeed by hogging the resource. If they’re annuals, they germinate so quickly when conditions are favorable that they get a jump on other plants and take all the water, nutrients, light and soil space for themselves. Getting rid of annual space hogs means first making space by weeding out the seedlings, and then seeding or planting something else while the resource is available.
Perennial space hogs like creeping or rampion bellflower (Campanula rapunculoides), shown here, can be even more challenging and frustrating to eradicate because they form mats belowground and aboveground, choking the soil so that other plants starve out. Large infestations of perennial weeds challenge our tendency to want perfection in our gardens, and perhaps change our sense of what we can live with and what we can’t.
Creeping bellflower is a great example: A common garden weed in rich clay soils across northern North America, it grows from thickened underground roots so persistent that often the most successful method for eradicating them is to dig up whole areas of soil to 6 inches deep and sift out the roots before replacing the soil. Small infestations can be controlled with vinegar and other natural herbicides; large infestations are often difficult to kill even with powerful chemical herbicides.
Applying the Right Techniques to Each Weed
The common dandelion (Taraxacum officinale), shown here, and Canada thistle (Cirsium arvense) are both perennials, yet dealing with them successfully means using very different techniques. This is where knowing your weeds pays off.
Dandelion grows from a taproot — simply pry it out of the ground, and it’s gone (if caught before its seeds blow around and proliferate).
Pry up a Canada thistle sprout, though, and soon you have more. These spiny weeds grow from rhizomes (underground stems); the rhizome responds to injury by producing more sprouts. Control involves repeatedly killing the sprouts spraying with ordinary white vinegar (works when they are small) until the rhizome itself is exhausted.
Keeping weeds out is not as simple as laying down layers of weed mat, no matter how careful you are. Pulling up weed cloth with plant roots tangled in it is no fun.
How can you prevent weeds? You can’t entirely. Weed seeds arrive on the wind, on the fur of your favorite pets and wildlife, on birds’ feet, and in other ways. You can be vigilant without being paranoid. Start by knowing your weeds through their life cycle so that you can recognize them at the seed and seedling stages, when they’re easier to control. Be careful about what you bring into your garden — check plant pots for “bonus” plants, make sure seed mixes are clean and don’t include contaminants, and check tools, boot soles and pet fur.
Don’t invite weeds in by leaving large areas of bare soil. Pay attention to what is sprouting where, and nip weed problems in the bud, or sprout, as quickly as you can. And remember that perfection is not natural.
Weeding as Good Citizenship
The second definition of a weed — the one about not playing well with others, where a plant disrupts ecological communities and processes — is an important one to remember.
Don’t garden in a way that allows plants with aggressive tendencies to escape into the wild. Hundreds of invasive weeds already cause problems on the North American continent — one study estimated that invasive species cause $100 billion in damages in the U.S. alone each year. Be a good neighbor by learning to identify and eradicate plants known as disruptive weeds.
Mindful weeding is simply good garden citizenship, part of leaving your patch of earth in better shape than you found it. We all want that.