Table 1: Weed-Control Techniques

1. Turn under the existing vegetation with a shovel, rototiller or tractor-pulled plough.
2. Allow weeds to grow to a height of 10 to 15 centimetres.
3. Remove weeds manually (hoe, cultivator) or by using a tractor-pulled disc. If perennial weeds are present, use a tractor-pulled harrow to drag roots to the surface, where they will wither.
4. Allow weeds to grow again and repeat step 3 until you are satisfied with weed control.* Each pass of the disc should be increasingly shallow until only the surface is cultivated on the final pass.

• Very effective at eliminating annual weeds.
• Loosens the soil to allow machine planting of plug plants.
• If perennial weeds are present in large numbers, the process can take one to three years, and some of the weeds may still persist.
• Not effective when tough perennial weeds such a Canada thistle and quack grass are present. When the roots of these plants are cultivated, many small pieces remain in the soil and each piece is capable of producing a new plant. Cultivation alone may increase these weeds.
• Cannot be used on waterlogged soils and may delay spring planting.
• Repeated use of heavy equipment can harm soil structure and beneficial soil life that has taken many years to develop.
• May leave soil prone to erosion by wind and water.
• Prolonged cultivation delays planting activity and results in loss of wildlife habitat for one to three seasons.
• Equipment suffers wear and tear.
• Cultivation machines consume fossil fuels and release emissions.

1. Glyphosate-based herbicide (e.g., Roundup®, Expedite Grass & Weed®) is applied to vegetation as per label instructions. Vegetation will be stressed or killed within two weeks.
2. Allow seed bank to germinate and grow up to 5 to 7 centimetres, then have the herbicide applied again. Repeat this process until you are satisfied with weed control.*
3. For shrub and tree removal, cut stems near ground level and treat stump with glyphosate-based herbicide (e.g., Roundup®, Vision®) as per label instructions to prevent resprouting.

* Measures required for effective weed control can vary. It is most important to gain control of perennial and biennial weeds.

• The Ontario Ministry of the Environment requires a glyphosate-based herbicide to be applied by a licensed commercial applicator who holds a valid Operator Licence and an appropriate Exterminator’s Licence. Homeowners can apply a glyphosate-based herbicide labelled as “domestic” on their own property without a licence. But remember, it must be applied according to the instructions. Read and understand the label before using the product.
• Suitable for small or large sites.
• Absorbed into the entire plant, including the roots, therefore effective at eliminating persistent perennial weeds.
• Does not disturb the seed bank; therefore, only the seed in the top layer of the seed bank germinates, reducing potential weed problems.
• Does not disrupt soil structure or soil life.
• Binds tightly to soil particles on contact so it will not leach into the water table.
• Does not persist in the soil.
• Kills or stresses all vegetation (even desirable species) that the chemical comes into contact with. In some cases it can be applied when desirable vegetation is dormant.
• Cannot be sprayed over water or on any wet area.
• Must be applied in dry weather and cannot be applied on windy days.

• Useful where topsoil has already been removed during construction activities.
• Prairie plants have a competitive edge on the poor soils that remain after the topsoil has been removed, although planting in very poor soil will result in less lush growth.
• Since the topsoil contains the seed bank and roots of weeds, removing it reduces the weed problem.
• If too much topsoil is removed, the subsoil below may be too acidic or too alkaline to support plant growth (do a soil test; pH should be in the range of 6 to 7.5; see Soil Analysis Services under Sources
  of Materials, Specialized Equipment and Services).
• Very expensive unless soil is removed as part of a construction process.
• Beneficial soil invertebrates are removed with the topsoil and can take years to become re-established.
• The specific fungi or bacteria that some plants
  require to survive are removed with the topsoil. Consider adding bacterial inoculant, see Beneficial Soil Organisms.

• Depletes nitrogen in the soil, which weakens weeds and reduces their competition with prairie plants.
• If too much organic matter is used, prairie plants become stunted and die.

• Practical only for very small projects.
• Plastic is difficult to pin or weigh down for extended periods (prairie and meadow are usually established on exposed sites).
• Most soil life is killed along with the plants and seeds. Life will eventually return to the soil but the long-term results are unknown.
• Persistent perennial weeds may not die.