Some people repeat Ralph W. Emerson, saying “A weed is a plant whose virtues remain undiscovered.” But although I appreciate that many weeds do have virtues, I doubt that many gardeners would accept that definition as the final word. Most of us have had extensive experience with Bindweed, Thistle, Goathead, Ragweed, Dandelion and Cheat Grass; not to mention some aggressive natives like Whiplash Daisy, Wood’s Rose and Hairy Goldenaster; and certain herbs like mints, Comfrey and Sweet Grass. So in talking about managing weeds non-toxically, the main point seems to be: How can we keep certain plants under control?
Having over 60 years experience in dealing with weeds certainly does not make me an expert, nor does 30 years as a nursery professional, but I will attempt to be helpful. To be honest, and not too fatalistic, weeds are plants that are tremendously adaptable and successful, and no amount of digging or toxic herbicides have been able to defeat them. In fact, you may know that since that toxic cure-all Roundup has been the most popular herbicide, many weeds have become resistant to Roundup including 14 US species and up to 34 species worldwide.
The two ways that weeds (and other plants) spread, are by seeds and by roots. Sometimes the seeding types can be controlled by mowing or removing the seeds before they ripen. Sometimes this doesn’t work 100%, as with Dandelions that can bloom after mowing, below the level of the mower. Sometimes weeds that spread by roots can be controlled by digging repeatedly, not allowing green growth to photosynthesize. Sometimes digging aids in spreading the weed as with Comfrey and Snow on the Mountain (Aegopodium).
In general it is important to find out what a weed likes, and restrict that: water, light, fertilizer. Water-loving weedy plant like Creeping Charlie (Lysimachia), vinca, ivy, Creeping Buttercup (Ranunculus) all can be tamed with drier conditions. An important strategy in conserving water and managing aggressive plants is grouping plants with similar water needs. Another strategy is to disturb the soil as little as possible so you are not bringing weeds seeds up into the light to germinate. The weeds are often the hardest to control in a new garden. The more a garden is planted, especially with tough groundcovers around taller perennials, and/or mulched, the easier it is to keep weeded. And the stronger the plants, the more they will outcompete the weeds for light and nutrients.
One of the more interesting books on weeds is Katrina Blair’s The Wild Wisdom of Weeds. She spends a lot of time discussing the many values of weeds (with nutrient-dense recipes), especially 13 “essential plants for human survival.” Not just a dreamer, this Durango woman has a masters in holistic health education, and a lot of practical experience. Her Turtle Lake Refuge organization provides greens for Durango school lunches, has a wild foods café and manages at least one park in Durango organically, along with several organic lawn care projects, classes and field trips, locally and internationally. She has had positive results with a homeopathic weed ash remedy detailed in her book. She will be giving a class at Harlequin’s Gardens _____.
Dr. Lee Reich, writer and horticulturist, has written Weedless Gardening. His experience-based approach is to feed compost and nutrients from the top without digging, mulching, making paths to prevent compaction and using drip or focused irrigation. By not turning the soil, weed seeds don’t get the light to germinate, by pinpointing irrigation, watering does not help weeds, and by supporting strong plants, weeds are not a big problem.
Charles Walters, founder of ACRES USA, in his book Weeds: Control Without Poisons, states that the major agricultural weeds “can be rolled back best with fertility management, and not with herbicides.” And he is specific: calcium for quackgrass, manganese for thistles; reduce phosphorus for cocklebur. Ragweed is decreased with greater porosity, air in the soil and more irrigation. Bindweed prospers in soil low in organic matter, calcium and soil life, and Dandelion prospers in low calcium, high phosphorus and high nitrogen, etc. etc.
My personal approach to weeding my xeriscape garden for 30 years is to use hand weeders, one with a sharp point, one broad and deep, and sometimes a narrow spade for the weed that got away. I start early in February or March digging out the weed grasses. They grow very fast in cool weather and can soon bury a small perennial. If you wait too long, the perennial comes out with the weed. Then in April (March) when the Bindweed is no more that 1”-2” tall, I hold the weed with my left bare hand while my right pushes a long bladed weeder under, swings and cuts the root. When I feel this, I pull out the hopefully 3”-4” long root and put it in my bucket. Small annual and other weeds I will often just lay next to the plant for mulch, but Bindweed can re-root, and big weeds with seeds must be taken away. This slice and pull method does not turn the soil.
Then if I have cut the roots deep, the Bindweed is stressed since it has not photosynthesized for a few months. So maybe I won’t see a new top for two weeks, then before the weed is more than 2”-3”, I dig again. This really stresses the Bindweed. By the time it is 2”-3” high again, my perennials and shrubs are bigger and leafing out which deprives the Bindweed of sunlight—another big stressor. I don’t start watering until May unless it is really dry, which gives an advantage to my established plants. Then I mulch where the ground is bare and later another round or two of weeding.
There are a number of non-toxic herbicides; most are vinegar or citrus-based with soap and maybe salt. We tested 5 kinds four years ago and only two proved really effective: straight vinegar 15-20% acetic acid, and citrus-based Avenger. Both perform best in hot sunny weather on small weeds. Truthfully, I don’t see the point of spraying a big weed which when it dies is a black dead thing that has to be pulled. Why not pull or dig it in the first place? There is a broadleaf herbicide IronX that is supposed to be non-toxic that I have not researched enough to recommend. Mulch really helps with weeding because the weeds come out so much easier
In lawns use corn gluten as an organic weed and feed. It prevents seeds from germinating and supplies 9% nitrogen. It is very effective even with Dandelions if you apply it spring and fall every year. Weeding in lawns is also reduced by mowing 3” high so the plant is stronger. Aerate once a year (Sept is best) followed by corn gluten or low-nitrogen fertilizer, then occasionally topdress with a fine compost.
Really bad weeds can be killed by solarizing the whole area with clear plastic (read how), or by cutting off the light, water and air with a sheet of pond liner. Weed barrier fabrics promise the moon and deliver many problems: the pores plug up in a few years and prevent water and air penetration, tiny weed roots go through holes in the fabric and removing them makes a bigger hole; and often the mulch blows off and exposes the ugly fabric. Paper, newspaper and cardboard make a good weedbarrier, covered with mulch and compost.
Weeds are here to stay. Toxic herbicides don’t solve the problem and they poison you, kids, pets and many smaller valuable beings. If you discipline yourself to stay on top of weeds, and plant and mulch, the weed problem gets to be less and less.
SIDEBAR: Negative Effects of Roundup
Many studies equate Roundup with its active ingredient glyphosate, but the Roundup Original formula is more than 400 times more toxic than the active ingredient. Roundup kills tadpoles, earthworm eggs, the gut biology in bees and humans and many species of soil microbes. The World Health Organization declared Roundup a “probable carcinogen” and glyphosate has been found in 93% of the people tested in the US. Of course, Bayer, the new owner of the Monsanto product, claims that for 40 years Roundup is proved to be perfectly safe. The USDA does not routinely monitor for glyphosate in our foods. Roundup residues are found in many GMO foods like soybeans, corn and canola, and in many processed foods.
Ref: BIRC, MegaFood