Weed control methods that workJun 01, 2022 03:15PM ● By Bryan Reed
Weeds perform the same functions as cover crops, adding organic matter to the soil, cycling nutrients from the subsoil into the topsoil, encouraging earthworms and beneficial microbes, breaking up compacted soils and providing nutrients to both humans and animals.
Contrariwise, they steal sunshine, suck up water destined for other crops and choke out vegetable growth. They can also make harvesting a real chore.
Weeds aren’t bad; they’re happy to grow and be part of our garden’s ecosystem—just not where we want them to be.
In her book “The Wild Wisdom of Weeds,” Katrina Blair documents the usefulness for 13 weeds commonly found in Colorado. Did you know that young lambsquarter can be a substitute for spinach, and it actually tastes way better? Dandelions contain vitamins C and E, iron, calcium, magnesium, manganese, potassium and protein, and they help with digestive issues, premenstrual syndrome and menopause. I even make a foliar spray from fermented dandelion leaves that stimulates growth in other crops.
How to prevent weeds
Like everything else in gardening, prevention goes a long way. Our biggest responsibility is not to let weeds flower and go to seed—which is difficult when they come in the wind and irrigation water, and from wildlife, animal manure and poorly made compost.
Crop-specific irrigation helps prevent weeds from spreading their seeds in your garden. Spray stakes, soaker hoses and drip irrigation supply water only to the plants we choose, whereas sprinklers water crops, weeds, the pavement and everything else in their path.
For plant starts, you can seed crops with a known range of germination days, then terminate the weeds just beforehand. For seeds with 7-10 days to germination, spray or flame weed the garden bed on Day 6 so the germinating vegetable seeds can outpace the weeds.
Another strategy is to thoroughly weed your garden beds, then transplant starts from 4-inch or 1-gallon pots so that they can stay ahead of the weeds.
If prevention doesn’t fully work, there are other sustainable ways to control weeds.
Mulch is a game changer for both suppressing weeds and retaining moisture in the soil. Overlapping cardboard or newspaper (four sheets minimum thickness), or using straw and leaves can also suppress weeds and add organic matter to the soil. (I prefer straw as opposed to leaves because it stays in place far better.)
Plastic mulch has become popular in the vegetable and hemp industries. Black plastic suppresses weed growth and lowers the soil temperature by shading it from the sun’s rays. White plastic reflects light up under large canopy crops (tomatoes, okra, etc.), red plastic increases tomato yields, blue plastic increases pollination in melons and cucumbers, and silver plastic has been documented to lower thrip populations on crops.
My PREFERRED method
When we weed whack bindweed, wild lettuce and plantain, we are actually pruning it back and forcing the plant to grow two new sprouts for every one we cut down. That’s why weeds come back stronger in just three to five days.
My favorite form of weed control is flame weeding. This non-chemical method is actually kind of fun and pretty easy to do, especially if you’re using a backpack propane tank (although any weed burner will work fine). It’s also gratifying to see all the crinkled leaves and brown, dead weeds the next day.
Flame weeding cooks the tips of the leaves (which is where the growth hormones are) and destroys the leaf tissue so that a new shoot must form at the roots and push up through the soil to grow back. This can take up to three weeks or more, making it far more effective than weekly weed whacking.
Flaming on low heat doesn’t use much propane, and pacing slowly back and forth usually does the trick. (Although I’ve been known to stand over goat heads and torch them to a glowing red! I’ve had too many bicycle tire repairs in recent years from goat head punctures.)
Weeds can be flamed within the rows of the garden, but remember to place a snow shovel as the base of the plant to shield your crops.
Pure vinegar is an excellent alternative to chemical herbicides that is very effective on weeds. Don’t use standard grocery store vinegar as it is only 5 or 6 percent acetic acid. You can find pure vinegar that is 30 percent acetic acid from most local hardware stores or garden centers. Acetic acid is also the main ingredient in naturally derived herbicide products like AllDown and Phydura, both which I’ve used effectively.
It's best to take down a majority of the weed biomass with a weed whacker or mower, then spray the vinegar on the remaining plant leaves and crown. Do this in the heat of the day when the sun is directly overhead. Wear gloves when pouring vinegar into a sprayer, as it can cause a rash on sensitive skin. And watch the wind so you don’t accidentally harm the plants you want to keep happy!