Taming Weeds

Their phenomenal growth rates and ability to survive in hostile environments have won some plants the unflattering designation of 'weed'. These maligned plants have a common trait: in their ideal environment, they almost always outgrow the fruits, vegetables, flowers and grasses we wish to cultivate. The question is how can you control weeds without destroying treasured plants or harming the environment? The place to start is with understanding why some weeds are more successful than others in the plant kingdom.

Along the sunny edges of forests and fields, blackberry bramble (a European import) overtakes its competitors by adding a metre of growth to its thorny branches every month in the spring and summer. Purple Loosestrife, sometimes referred to as a 'beautiful killer', hitched a ride in the grain and ship ballast from Europe approximately 200 years ago and now threatens to overtake vast tracts of wetlands and fertile fields. Purple Loosestrife destroys wildlife habitats by displacing the native vegetation that provides food, shelter, and breeding areas for birds and other wildlife. The secret to this weed's success is in its ability to produce up to 3 million windborne seeds each year! On ranch land and farms, knapweed greedily consumes water and light, crowding out other plants. In their native habitat, weeds such as these are somewhat contained by climate, insects and competing plants but some become noxious weeds when transplanted in a new area. There are also the indigenous weeds that most of us are familiar with from our own yards such as dandelion, clover and coltsfoot.

Weeds are spread in a number of different ways: by birds, animals, wind, water, vehicles, seed and plant shoots, to name just a few. People are also unwitting accomplices in the spread of weeds. For example, many garden varieties of purple loosestrife were considered to be sterile, safe horticultural cultivars. Recent scientific studies have shown that these varieties are indeed capable of pollen and seed production. These plants can readily cross-pollinate with other garden varieties, as well as wild loosestrife populations. In a Manitoba study, Morden Pink cultivars were planted near a wetland with purple loosestrife and six months later all Morden Pink plants produced viable seed. The majority of wild infestations of purple loosestrife are the result of garden escapes.

Methods to Control Weeds


Flamethrowers and handheld Butane or propane torches are an effective, non-chemical method of controlling weeds. Plant cells are full of liquid sap. When intense heat is applied to the plant, the sap boils bursting the cell walls and killing the plant or destroying a portion of it. Some hardy species can re-grow from the roots so it is essential to remove the roots as well. When using the flame method, be sure that there is no chance that fire can spread.

Soil Improvement

Keeping weeds out of lawns can be a full time job. Healthy soil gives your grass a fighting chance. Supplement your yard with compost, well-aged manure, and fish fertilizer. Heavy, infrequent watering will encourage your grass to develop deep roots. During extended dry periods, the grass will survive as young weeds wither. Adding lime and a nitrogen-rich fertilizer will help to create unfavourable conditions for weeds such as clover.


Aeration will also help to improve your soil and make it less favourable for some weeds, which thrive in compact turf. Use a handheld or motorized aerator to increase airflow and reduce soil compaction. Push the aerator down into the soil at an angle to remove soil cores then leave them on the lawn to dissolve.


Avoid mowing too low. Short grass offers less competition for weeds and also dries out faster in hot weather.


With the discovery that certain pesticides and herbicides contribute to leukemia and other diseases-especially in children--homeowners are looking for alternatives to chemicals. One of the most effective weed control methods is simply to dig them up. Over the years, many specialized implements have been developed to tackle different types of weeds. The "Fish Tail Weeder" is a long sharp implement perfect for digging up the taproots of dandelions. The Japanese Weeding Knife can cut through tough branches and fibrous roots. You will also find tools with such names as the "Claw", "The Ideal Weeder", and the "Gooseneck Weeder". Fill in holes left after removing weeds with soil and sow fresh grass seed.


A layer of horticultural fabric, bark chips, cocoa husks and other types of mulch will block out sunlight from weed seeds and seedlings. Mulch will also help the soil retain moisture reducing the need for watering.

Chemical Herbicides

Check with a qualified horticulturalist for information on the proper type of herbicide for your needs. Many herbicides can be harmful to people, pets and the environment. Applying the product at the right time of year and in the right quantity will help you maximize its effectiveness.

Alternative Herbicides

Burnout Weed is a non-toxic, non-selective herbicide containing a concentrated formula of vinegar and lemon oil. This product will stunt or kill many types of plants so use it as judiciously as you would a chemical herbicide.

Beneficial weeds

As the old saying goes, if you can't beat 'em, join 'em! With the wind blowing in seeds from neighbouring properties, it won't be possible to permanently eradicate weeds from your lawn and garden. Fortunately, weeds have their benefits. Clover, for example, will add nitrogen to the soil. Yarrow is rich in minerals and is a good addition to a compost heap. Yarrow also has medicinal properties, and if left uncut will produce attractive white flowers. Dandelion (Taraxacum officinale) has medicinal properties as a blood purifier and diuretic. In addition, its long taproot will mine minerals from deep in the subsoil to be made available via the compost heap.

Weeds can spread their seeds and outgrow many cultivated and indigenous species so your efforts to control weeds will not only make your lawn and garden look better, your neighbours and local farmers will thank you.

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