Did you know there are 6.2 million lawns in Canada? These days, many of us are concerned about the environmental impacts of maintaining all that turf grass. Read on for Astrid’s approach to sustainable fall lawn care in this, the year of the ecological garden.

It Begins with Soil

Caring for a lawn holistically means caring about the lawn that we DON’T see. Soil is home to 25% of the earth’s biodiversity; this species richness is an important part of healthy soil, which in turn supports healthy plants, including the grasses in your lawn. 

Sustainable lawn care means seeing things from the point of view of relationships in nature and working with, rather than against, natural systems.

What about Fertilizers?

Synthetic fertilizers are a quick fix for tired lawns, supplying the nutrients (primarily nitrogen, phosphorus and potassium) needed by all plants. Unfortunately, they are ultimately damaging to the soil that supports those plants. Synthetics are high in salts and reduce the numbers of beneficial soil microorganisms (responsible for decomposition of plants into nutrient rich organic matter). They may leach into nearby bodies of water as runoff. Over time, synthetic fertilizers damage the natural composition of soil and the all-important soil-food web. 

Lawn Challenges

Maintaining a “perfect” lawn certainly presents challenges. Perhaps foremost should be the decision as to whether a perfect lawn is a desirable goal!

That said, one concern of lawn owners is the buildup of thatch. This is a layer of partially decomposed plant stems and roots found between the green stems and crown of the grass plant and the soil layer. Because it is densely woven together, it resists penetration by water, which then tends to simply run off. Contrary to some sources, grass-cycling (leaving cut grass on the lawn) does not contribute to thatch, especially if grass is finely chopped with a sharp mower blade. The primary cause of thatch is poor soil – soil that is low in organic matter and beneficial soil microbes which prevents thatch build up. The result is compaction.

Mechanical aeration is another concern – whether to do it or not. This process uses a tool with a hollow cutting blade to remove plugs from a lawn. The purpose is to reduce soil compaction and to ensure water and air can penetrate into the soil more readily.  It is not generally necessary or recommended for a home lawn, though it may be useful in particularly high traffic, heavily used spaces. 

The solution for compaction then is not de-thatching or aeration but proper lawn care – maintaining soil health, seeding, watering and cutting.

Soil Health

Astrid boosts the health of her lawn by adding compost each fall. She uses AA fine grade (sieved) leaf and yard waste compost, from a local supplier, spread to a depth of about 0.5 cm. Beyond the benefits in terms of nutrients, this organic matter also increases the water holding capacity of soil and introduces microorganisms which in turn support plant growth.

Seeding

Fall is an ideal time to tackle over-seeding of bare or thin patches of lawn. Astrid advises choosing a seed mix with a variety of types such as fescues, perennial ryegrass and white clover (which fixes nitrogen). A combination of grass types tends to be more resilient than a single species. Reputable seed companies can advise what blends might work best in your conditions (zone, soil type, sun exposure). 

For her yard, Astrid prefers OSC low maintenance Eco Lawn mixture to which she adds clover.  She also adds an endo-mycorrhizal inoculum to the seed, as mycorrhizal fungi will colonize the root system of the grasses, increasing their ability to take up moisture and nutrients. These even help with water sharing in times of drought.

To over-seed (mid September):

• Scratch the surface of the soil gently with a stiff rake (avoid ripping the grass crowns)
• Coat the dampened grass seeds with the end-nycorrhizal fungi powder and let dry
• On a cloudy day (fungi are UV sensitive), broadcast the seed/mycorrhizae mixture according to the package instructions
• Cover with a 3-4 mm layer of fine compost
• Water every second day to ensure seed germination

Fall is Coming….

A thick layer of fall leaves will smother grass and should be raked. Astrid stores her collected leaves in a wire mesh bin allowing them to decompose. The following year her garden benefits from the resulting leaf mould, which she uses as a mulch and fertilizer.

A few leaves can be left on the ground and chopped with the lawn mower, thus providing a food source for the microorganisms in the soil.

Watering

Watering regimes depend in part on soil type. Sandy soils, for example, drain quickly and therefore may need more frequent watering than clay soils. Lawns generally prefer infrequent but deep watering, to encourage deep root growth. This can range from 2.5 cm weekly to monthly, depending on rainfall and other factors. A rain gauge is useful in determining whether rainfall needs to be supplemented with watering. And yes, lawns should be watered through the fall if rainfall does not suffice.

Cutting

In the fall, your lawn will typically grow more rapidly than in the sun scorched days of mid summer, when grass plants tend to go dormant. In cooler weather, mow regularly to a height of about 4.5 inches to encourage optimal root system development. Be sure to use a sharp mower blade to make a clean cut. A dull blade rips the grass, encouraging disease.

No more than one third of the leaf should be removed at each cutting, so that each blade still has plenty of surface area remaining for photosynthesis. There is no need to remove grass clippings as they will simply decompose, returning moisture and nutrients to the soil.

Sources

For compost: Tomlinson Organics

For grass seed: OSC Seeds