Managing Weeds in Your Lawn without Pesticides

Some new cultural practices will soon need to be implemented in order to maintain lawns within historical expectations in regard to color, density and uniformity. We all understand that healthy lawns almost always means fewer weeds. Pesticides have been used as the main response to weed growth. Without pesticide intervention, we have to increase and focus on cultural practices. Mechanical intervention for weed control will in most cases increase the cost of managing weeds.

Drainage

• Most soils in the Greater Victoria area are clay based. These are mostly healthy soils, however, the down-side is compaction and that means poor drainage – especially if the sub-grade within the soil profile has not been adequately graded.

Healthy soils

• Healthy soils are not always a given. Most commercial installations have clay-based soils that are amended. Many are really no more or less than “catch of the day” products that have been cobbled together on mixing sites. This increases the challenges turf management.
• Amending the soil (as possible) is the first step towards a healthy lawn.
• Top soils can be renovated over time through top-dressing. Or, more dramatically by totalrenovation.

Choosing the right grass species

• There are many new lawn cultivars. It is suggested that if a lawn has not been seeded within the past 10 years, then there is a better grass cultivar on the market for your situation.
• Lawns should be seeded with the correct selection – however, they can also be over-seeded to achieve the same results.
• For most commercial and residential applications, perennial rye grass is the grass of choice. It provides for quick germination and recovery when over-seeded.Reducing Shade
• Very few turf grasses respond well to shade. As gardens mature and trees and shrubs grow, the lawn often receives less light. Advancing shade is often a major growth impediment to turf grasses.
• Pruning to increase light is an important cultural practice to increase turf growth.
• Removal of trees may also be necessary – if lawn is important.

Management Practices

• Aeration: the most important lawn practice in clay soils is aeration; most lawns should beaerated at least twice per year – or as required to maintain healthy growth.
• Mowing: mowing heights should be varied by season; taller grass during the warmer monthswill regulate the soil temperature promoting cool season grasses and removing light for weed growth. Perennial Rye grasses should be mowed to 2-3″ during the summer, 1-2″ in the cooler months.
• Irrigation: public enemy #1 for turf grasses is excessive watering – especially when automatic irrigation systems are installed. Watering should be limited to twice weekly cycles – irrigation should be deep and infrequent. Many commercial irrigation systems are not properly zoned or balanced, which creates serious management issues.
• Fertilizing: Slow release fertilizers are now available for turf grasses. Best management practices should always include these products. Also, many organic products are available – however, they tend to be more costly to apply. Fertilizing should be applied with the rule of less is often better than more.
• Acidity: Soil pH should be maintained at slightly acidic levels for local turf grass (pH = 6.5)
• Top dressing: Top dressing is an important management practice to improve top soils and drainage. The addition of top dressing material can increase drainage with medium sand.
• Drainage can also be increased with the inclusion of organic material in the top dressing. The breakdown of organic material is a natural source of bacteria and plant nutrients.

• Controlling thatch: Power-raking of the turf is a common management practice to controlthatch. If the lawn is raked, it provides an opportunity for top dressing and over-seeding for a full, economical lawn renovation.
• Soil biology is the best, natural defense against thatch build-up in the turf. Good aerationdevelops good microbial activity – reducing thatch.
• Reducing moss: Moss should be considered as a turf weed with no roots. Moss thrives inconditions where grass does not. Moss is tolerant of shade, compacted soils, excessive shade. Moss will grow where there is poor density in the lawn. Conditions that promote healthy turf normally mitigate against moss growth. The common chemical intervention is Iron Sulphate. This product is commonly available and is acceptable under most municipal pesticide bylaws.

Accepting some (more) weeds

• Healthy lawns can support some low levels of weed. As mowing heights are raised during summer months, low levels of weed are shaded out due to increased lack of light and increased density.