Weeds are plants with an indomitable will to live — they are tough and strong and strategic. They can hug the ground, creating a large footprint, or they can stretch up into the air towering over everyone else. They can have long, deep taproots or delicate hairy ones, both of which will regenerate given the slightest chance. Some of them are creepers, reaching out above ground and sending down new roots at every node. Others travel underground, reaching upward for light at every node. And all of them produce seeds, whether they are annual or perennial.
Not at all scary, even edible, is the common pineapple weed — what country people back in the day called dishwater weed because it grew so well where nothing else would; in the cracks of your driveway, in dry gritty soils. It is a relative of chamomile and is edible, although it becomes somewhat bitter when it finally blooms. It has ferny leaves and small yellow flowers that look a little like a pineapple up close.
Another common weed is broadleaf plantain. It’s wide, ribbed leaves resemble a poor man’s hosta. They hug the ground, sending up five to 15-inch spikes of flowers that quickly become seeds. Imported to North America as a food for its nutritious leaves that are high is vitamins A, C, and K, as well as calcium and iron, it spread so rapidly that the aboriginal people called it “white man’s footprint”. It tastes like asparagus when harvested young or when new shoots appear after mowing. This is also a very useful medicinal plant that was considered by the Saxons to be one of the nine sacred herbs.
Useful or not, sometimes you just want those weeds out of your garden or lawn. Some gardeners say fall is a really good time to pay them some attention. As the days get shorter and the temperatures fall, all plants slow their metabolism down, storing food in their roots for the winter. It is hoped that weed killer, applied at this time, will be absorbed and stored down there giving the poison time to do its evil deed. In fall, it might be a good idea to mow first so that there are exposed surfaces open to the product penetration. And do it when the temperature is still above 10 degrees C (50 F).
Others suggest that spring is the best time because weeds are actively growing. Reality says that anytime is a good time to tackle weeds.
If you are going after weeds in the old fashioned and truly environmentally responsible way, you will pull them. In fall, the ground is likely to be hard and dry, making it hard to get tap roots and others out in one piece. Watering the night before will loosen the soil and aid this task.
After pulling by hand, sprinkle down a little topsoil and seed to provide competition for whatever bit of roots or weed seeds you left in the soil.
To reduce the new crop of seeds in spring, many people use a pre-emergent application of something such as corn-gluten meal. It will inhibit the germination of dandelion and other seeds. But it will also inhibit the emergence of any new grass seeds you might lay down. Non-selective weed killers such as Round-up (glyphosates) kill everything. Selective post–emergent killers will attack only certain weeds, such as broad leafed weeds (the ground huggers) and broadleaf plantain. Read the label to see if it will kill crabgrass and quack grass, but the best way to deal with these two is to pull them when they are young.
One savant recommends vodka as a weed spot-killer. The recipe is one ounce of vodka to two cups of water and a drop of dish soap to make it stick. The vodka is supposed to dry the weed out in much the same way as do salt and vinegar. These cures, by the way, are best used on patios or driveways, away from other plants, because they are non-selective. And remember, if you have a torch weed-killer, you don’t have to scorch the walkway. The University of Manitoba says it just takes a brief encounter with the heat to kill the plant down to the tips of its roots.
Some weeds are more than noxious, they are killers. While not to be found in your lawn, they are worth knowing about. Poison hemlock (Western water hemlock, in more westerly parts of the country) is one example. It is unrelated to the tree, but it is the weed whose seeds, steeped in water, were used to kill Socrates. Don’t confuse it with Queen Anne’s lace, a pretty and benign plant that it resembles. Poison hemlock (Conium maculatum) can grow three to eight feet tall, while Queen Anne’s lace tops out at three feet and presents denser flowerheads. Ingestion is the main danger, but even getting it on your skin or breathing in oils diffused into the air on a hot day can cause respiratory problems. It attacks the central nervous system and takes 48 to 72 hours to do its fatal job.
It’s not hard to identify giant hogweed (Heracleum mantegazzianum), the noxious plant whose sap can blind you and cause terrible burns and blisters when exposed to skin and sunlight. This plant is massive, growing 12 to 15 feet in height, with flowerheads that can become one to two feet in diameter. It looks like a giant Queen Anne’s lace, but its stems and leaves have purple splotches on them. Stay away!
Dorothy Dobbie is the publisher of the Manitoba Gardner Magazine, serving Manitoba for 20 years. Listen to her weekly radio show on CJNU, 93.7 FM at 8:00 Sunday mornings. For subscriptions to the Gardener, Call 204-940-2700 or go to localgardener.net