But no matter how many weeds they've plucked, even veteren gardeners get stumped at times trying to determine what is, and what is not, a weed — particularly in the spring when everything is just beginning to peek out of the soil and your winter brain has wiped all your geographical gardening memories clean. "Is this where I planted a patch of Primrose or are these weeds that need to be annihilated?"
JP: Since every province is unique, it's wise to refer to websites with information specific to the province you live in.
What should you do if you aren't sure if it's a weed or a flower?
A plant expert answers questions about every gardener’s nemesis.
Purslane ( Portulaca oleracea ) is one of the most common garden weeds and you'll also find it creeping along the cracks of your driveway and between your interlocking brick work. This 'annual' weed whose origins are debated features fleshy, flat reddish-green leaves which creep along the soil on thick prostrate stems and small yellow flowers which open only on bright sunny mornings. The fleshy leaves and stems are basically organs for water and nutrient storage which can give them an advantage in dry soil and drought conditions and help them tolerate compacted soils. The fleshy nature of purslane enables it to continue to flower and produce seeds for several days after being pulled and it is important to get every part of the root removed as it will re-establish quite effectively from even a small portion of root remaining in the soil. Just like dandelion, this species has a long ethnobotanical history and is becoming popular once again in the culinary world.
It really comes down to hard work. Hand pulling is my go-to control method — I like to provide some irrigation or wait until after a good rain to pull weeds while the soil is moist so the pulling is easier. Also, try to find time to pull weeds regularly as the smaller they are, the easier they will be to remove. Timing of pulling some weeds is also critical. You want to ensure you pull them before they set seed so that the problem isn't persistent. Also, remove all pulled weed debris from the garden and do not incorporate it into your compost bin. Other methods of control can be used at the proper time of year (and some with guidance recommended) including: cultivating and tilling the soil, solarisation (using polyethylene sheets laid on the soil surface to cook the weeds and their seeds); adding nutrients (as many weeds prefer nutrient poor soils); and by planting a plethora of desirable plants. By filling the empty spaces with desirable trees, shrubs, perennials and groundcovers, you will eliminate the soil space and sun exposure available for weeds to germinate and multiply.
I'm lucky. I get to spend most mornings strolling through my garden, coffee in hand, admiring my plants and pulling weeds that dare to raise their unwelcome heads. I find that weeding regularly makes gardening less of a chore and it's an effective way to stretch a little before breakfast as well.
JP: Weeds vary dramatically within small areas so every region of Canada is unique. However, from province to province and within each local ecotype, certain weed species will be more prevalent than others. Many common weeds and invasive species are thankfully more prominent in agriculture (Lamb's-quarters — Chenopodium album ) and in natural areas (Common Reed — Phragmites australis ) than they are in our gardens; however, there is some crossover between those areas and our gardens.
JP: Weeds can move around in a variety of ways — sexually and asexually, as discussed above, but they can also travel by wind, water, birds, insects, animals and even by hitching a ride on garden tools, power equipment, the mud on your boots or the tires on your truck. When a weed spreads asexually like this, it only requires one parent and the offspring is genetically identical to that parent.
Dandelion ( Taraxacum officinale ) is most prominent within our over-abundance of turfgrass but are prevalent within our garden beds as well. A plant which needs no description and is one of the most easily recognized plant species in Canada, dandelions can grow in a variety of conditions and are very successful in their reproduction and dissemination via wind dispersed seeds. Their thick taproots can make them virtually impossible to pull and eradicate and dandelions provide early food sources for pollinators in spring, so some Canadians have learned to live with them. Interesting that they were probably brought to North America as a medicinal herb and are again becoming popular as a culinary superfood.
JP: Weeds can tell you a lot about your soil because all plant species prefer specific environmental conditions in order to thrive. Does the soil have too little nitrogen or is it eroded or too compacted? Spotting weeds that signal these issues can help you make helpful changes such as tilling and/or adding organic matter. Some 'weeds' such as Goldenrod ( Solidago species) and Joe Pye Weed ( Eutrochium purpureum ) are native species which support Canada's pollinating insects and birds and contribute to the ecosystem. Milkweed ( Asclepias species), for example, provides a nursery for the offspring of Monarch butterflies. Also, Queen Anne's Lace ( Daucus carota ) is also considered a weed but can be beneficial in that it attracts predatory wasps, flies and lady beetles which prey on garden pests such as aphids.
Canada Thistle ( Cirsium arvense ) sounds like it's native to Canada however, it's actually a descendent from Asia and Europe and should be called 'Creeping Thistle' or 'Field Thistle' in order not to confuse us. This "noxious weed" reproduces by wind-dispersed seed and by a colonizing root system which allows it to form dense patches or monocultures. Canada Thistle is a ruderal species — a species which is first to colonize disturbed land. The spread by an underground network of roots, along with the spiny leaf edges and stems, make this weed difficult to deal with in any situation. Though it's a pest in the garden, this species also plays an important role in the ecosystem. Its purple flowers are visited by a wide variety of insects, the seeds are an important food source for birds like goldfinch and its leaves are used as food by many species of butterflies and moths.
JP: There are some commonalities which weeds possess in order to gain advantage over desirable ornamental plants. First, they reproduce in a variety of ways. They can spread sexually by seed as well as asexually via rhizomes — a stem that runs underground and shoots out roots like tentacles. Second, some weeds outcompete other species by leafing out earlier and blocking the sun to slower growers. Also, they often hold green leaves later in the fall as well, giving them more time for photosynthesis which ultimately provides them more time and energy to grow, create more seeds and reproduce. By thriving in a multitude of conditions, rapidly establishing and spreading, and by populating areas during droughts, floods and other extreme conditions, weeds have cornered the market on survival.
What weed-killing options can you recommend?
Do you think gardeners are too touchy about weeds — should we be more forgiving?
JP: No, all weeds come from the kingdom of plants and all weeds will produce flowers (or equivalent reproductive organs). They're definitely the underappreciated relatives of some of our most beloved garden plants. For example, what may be considered a weed in British Columbia might be considered a garden gem in Ontario. On a larger scale, a beautiful culinary herb that is desirable in Europe and brought to North America for its desirable characteristics can become a menace — even invasive. Such was the case with Garlic Mustard ( Alliaria petiolata ) which is now a common unwelcome resident in many Ontario gardens.
Which Canadian weeds are particularly dangerous and/or invasive?
JP: There are a number of weeds which are considered noxious or invasive and they are generally defined as species whose introduction or spread threatens the environment, the economy, or human health. In Ontario alone, there are over 400 species considered to be invasive. In Canada, invasive plants cost an estimated $2.2 billion each year by reducing crop yields and quality and increasing the cost of weed control and harvesting.
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You can typically recognize this plant by the following particularities.
This weed can reach an impressive size about the maturity time. In the proper climate, it can even grow to 7 or 8 feet (2 – 2.5 m) in height.
A layer of hair covers all parts of the plant, giving these plants a silvery appearance. However, the densest is found on the surface of the leaves.
5. Japanese Knotweed.
Himalayan balsam (scientific name Impatiens glandulifera) is also commonly known as policeman’s helmet, copper tops, gnome’s hatstand, Ornamental jewelweed, Indian jewelweed, bobby tops, touch-me-not, as well as a few other names.
These are ten plants with a tall thick stalk that might pop up in your yard or garden without your allowance. The list could probably go on and on since there are a lot of other weeds that would fit these criteria.
Tall weeds with thick stalks are invading your yard or garden and don’t know what kind of plants are those? I made a list of plants with thick and tall stems to help you identify the intruders.
Wild lettuce is an annual or biennial herb in the family of Asteraceae (same family as dandelions). It is widely considered a weed and is the closest wild relative of cultivated lettuce.
When pokeweed doesn’t carry fruits, you should be able to recognize this plant by its thick purple stems with green-to-white flowers or lance-shaped green leaves.
Ricinus (Ricinus communis), also known as the castor bean or castor oil plant, is a fast-growing perennial shrub in the spurge family. It is a plant native to Asia and Africa and grown as an ornamental plant in many parts of the world. Ricinus can reach the size of a small tree, about 12 m (40 ft), in hot climates.
When are only saplings, the paulownia tree can be easily mistaken with a gigantic weed if you’ve never seen one before. It has a thick and tall stalk and large flat green leaves.
7. Giant Hogweed.
Pokeweed is a perennial weed in the Phytolaccaceae family, native to eastern North America, the Midwest, and the Gulf Coast, as well as to some European and Asian countries.
Giant hogweed has a stiff stalk that can grow more than 4 m (13 ft) high and up to 10 cm (3.9 in) in diameter. A mature plant has gigantic incised and intensely lobed leaves that can reach between 1 and 1.5 m (3-4 ft) wide.
Giant hogweed (scientific name Heracleum mantegazzianum) is a perennial flowering shrub in the family of Apiaceae (same family as carrots). This plant is indigenous to the western Caucasus region of Eurasia. Just like many other weeds, Giant Hogweed has spread as an ornamental plant to numerous countries, and it is now on the noxious weed list of many.
While a blooming agave is probably the champion when it comes to plants with tall thick stalks, I have omitted from including it in the following list because it’s not usually a plant that simply pops in someone’s yard out of the blue.
Besides the production of oil and food, some species of sunflowers are also used as ornamental plants in landscaping.
9. Common Mullein.
A mature plant has hollow robust stems with distinct raised nodes similar to those of bamboo. These can grow up to 13 ft (4 m) each season.
Pokeweed holds a potent toxin, which is extremely poisonous to humans, pets, cattle, and other farm animals. Its fruits look like berries but are also very toxic. However, there are some species of birds and small animals that are immune to this poisonous substance and consume them.
During the first year of life, the plant only produces a rosette of leaves on the ground, and only in its second year, it develops a stalk that can grow up to 2 m (6.5 ft) tall. This ends in a dense inflorescence that can occupy up to half of the stem length. The flowers are yellowish and have very short pedicels.
Common Mullein by Ryan Hodnett / CC BY-SA.
This plant has several other names such as phytolacca Americana, dragon berries, American pokeweed, or poke sallet.
Creeping Thistle by AnRo0002 / CC0.
The Spruce / K. Dave.
The flowers of stinging nettle plants are inconspicuous. You'll pay plenty of attention to its barbs, however, if you're unfortunate enough to brush against stinging nettle! The discomfort these weeds can cause seems incongruous with the fact that stinging nettle is edible. But the young leaves of stinging nettle are, indeed, cooked and eaten by wild foods enthusiasts. Just be sure to pick at the right time and prepare properly to ensure safe consumption.
The Spruce / Evgeniya Vlasova.
It's not for nothing that this plant is named, "giant ragweed." It can grow up to 15 feet tall, with thick roots and branches. Like its ragweed cousin (and unlike goldenrod), giant ragweed produces a great deal of pollen which causes serious allergies.
The Spruce / David Beaulieu.
Purslane (Portulaca olearacea))
Here are 17 types of weeds you might encounter in your garden.
Bgfoto / Getty Images.
The Spruce / K. Dave.
Polygonum cuspidatum goes by several other common names, including Japanese knotweed and fleece flower. Several other common names include the term, "bamboo," such as "Mexican bamboo." While its autumn flower does, indeed, look fleecy, "fleece flower" is just too dainty a name for so tenacious a weed!
Purslane is the edible weed, par excellence . Purslane contains five times the amount of essential omega-3 fatty acid that spinach has, and its stems are high in vitamin C. A succulent mat-forming plant, it has a crispy texture and interesting peppery flavor. It is often served raw in salads but can also be cooked as a side dish.
Once you've identified nuisance plants, you can more readily access information on eradication. In some cases, however, finding out more about the plants in question may persuade you to show more tolerance toward them. There are even some edible weeds. Some are worth your time to remove while others don't cause much harm (and may even have beneficial aspects).
Like curly dock, orange jewelweed (or “jewel weed”) can be used as a home remedy for poison ivy. The taxonomic name of orange jewelweed, Impatiens capensis , classifies it as a wild version of the colorful impatiens flowers sold so widely for shady annual beds.
There are three plants named, “bittersweet.” American bittersweet is harmless, but Oriental bittersweet should be regarded as a weed since it can harm your trees. The third type of weed that goes by this name (bittersweet nightshade) is one of our most poisonous plants, despite being related to the tomato.
The Spruce / Jordan Provost.
Stinging Nettle (Urtica dioica)
Several of these weeds can cause rashes. Use proper clothing and gloves when working around these weeds, or enlist professional help to eradicate them.
While many consider clover a “weed,” there’s really nothing wrong with having a little clover mixed into your lawn. The Irish consider various tripartite clover leaves (such as the one in the photo here) to be “shamrocks.” The tradition behind the shamrock is quite distinct from that behind four-leaf clovers.
Dandelions are a harbinger of spring. Their bright yellow flowers often poke up through lawns and appear between cracks in driveways and sidewalks. The seed heads of dandelions are probably better known than those of crabgrass, but dandelions are perennial, not annual weeds.
Poison sumac is a shrub (some consider it a small tree) that grows in wet areas, often next to Cinnamon ferns and cattails. You will not find it trailing over the ground or climbing trees, as you sometimes find poison ivy. Every part of the plant is poisonous, meaning it can cause serious rashes if touched. As is often the case with toxic plants, it can also be very attractive; its white berries and bright fall foliage is pretty as well as dangerous.
The Spruce / Lindsay Talley.
While dandelions have multiple medicinal uses and can be eaten in salads or used to make wine, many homeowners would prefer to eliminate dandelions. Keeping dandelion seeds from germinating won’t be enough to get rid of dandelions. It’s possible to use herbicide to eliminate your dandelions, but the most effective and least harmful approach is to dig the flowers up from the roots.
Giant Ragweed (Ambrosia trifida)
The Spruce / Adrienne Legault.
The Spruce / Evgeniya Vlasova.
The Spruce / David Beaulieu.
Hedge bindweed has a fairly attractive bloom, similar to that of the morning glory, which can be white or pink and have a pleasant fragrance. But this is no innocuous weed. If you let hedge bindweed get out of control, your yard will feel like Gulliver in Lilliput. There is a reason for that "bind" in "bindweed."
The Spruce / David Beaulieu.
Ground ivy, a common lawn weed, goes by a number of names. For instance, it is also called "gill," "gill-over-the-ground" and "creeping charlie." Although considered a weed, ground ivy has a pretty flower and, when you mow this weed, it gives off a pleasing aroma. Ground ivy is also used as a medicinal herb.
Wild madder is, like sweet woodruff, in the Galium genus. Wild madder is also called "bedstraw." Apparently, people did actually once use this weed as a bedding material. Sweet woodruff is a creeping, mat-forming perennial that pretty clusters of white star-shaped flowers in spring and has very fragrant, lance-shaped dark-green leaves.