Organic Lawn Care with Astrid

Astrid shares her approach to lawn care – a regenerative practice. She explains this, and then goes on to discuss some commonly used lawn care methods. Finally she shares practical suggestions for lawn care and – a bonus – how to make compost tea. The blog ends as always, with your questions.

While there are a number of alternatives to lawn (think meadow), many of us still love the soft green expanse. It allows for children and animals to run and provides an ideal surface for playing sport.

So, how do you keep your lawn healthy and beautiful? Astrid suggests using regenerative practices . The aim in care is renewal or building rather than merely sustaining (prevention of depletion). This approach sees lawn, as a part of a complex relationship of interdependence with a soil teeming with life. Plants above the soil exchange nutrients and water with organisms below the soil. The health of the elements is this system are interdependent.

Did you know that grass, trades 50% to 80% of the carbohydrates it produces from photosynthesis with organisms in the soil.

The soil beneath our feet is the living source of all plant nutrition and the top few inches have the greatest biodiversity. Here we find microbes and mycorrhizal fungi.


  • Convert Nitrogen (which makes up 78% of air) into a form usable for plants
  • Build homes in the soil creating aggregates with improved air and water holding capacity
  • Constantly recycle organic matter

Mycorrhizal fungi

  • Connect most plants in the garden and are a first line of defence
  • Share water with the grass

To develop and maintain a healthy lawn, increase biodiversity; above ground using diverse seeds and clover, and below ground, with compost including microbes and mycorrhizal fungi.

For more information on soil health visit the Society for Organic Urban Land Care

The low down on some commonly touted lawn improvement techniques

Artificial fertilizers

While they are effective they have a number of disadvantages

  • They inhibits the forming of associations in the soil
  • High salt content can kill beneficial microorganisms.
  • The plants grow too fast and are not robust
  • The more you feed the more plants need – as if they are on crack.
  • Excess nutrients runoff, enter into our water systems and create problems with water quality. (One example; you can buy fertilizer with the following ratio of nutrients: 30 Nitrogen – 0 Phosphorous – 3 Potassium ; concentrations never found in nature).

Mechanical aeration

Use this only in the most desperate of situations as it is very invasive. Do once in the fall, then remediate by adding good compost and grass seed.

Dethatching services

Organo-lawn describes lawn thatch as “composed of a tightly intermingled layer of stems, leaves and grass roots, which accumulates between the vegetation and the soil. Too much thatch increases the turf’s susceptibility to lawn diseases, reduces its tolerance to drought, cold, and heat stress; and hinders the movement of air, water, fertilizers, and nutrients into the soil. In severe cases roots of the grass will not grow into the soil but only take root in the thatch layer making the turf susceptible to drought and heat stress.” Astrid says that thatch is an indicator of poor soil health which leads to compaction….so that’s the cause of thatch.

So dethatching will not solve the problem. A better approach is to encourage a healthy living soil and that means you have to add good quality compost to get the numbers and diversity of soil microbes up. Then, leaving the grass clippings after mowing will continuously feed the soil microbes – so no chance for thatch build-up. It’s the food chain sustaining your lawn.

Best regenerative practices

Lawn rehabilitation

The best time to rehabilitate your lawn is in the fall. Aerate (as a last resort), add compost and reseed bare patches with a biodiverse blend including fescues, ryes and up to 30% clover. (Clover fixes nitrogen in the soil). The compost will hold water which in turn will support germination of your seed.

Choose quality grade A seed and add mycorrhizal fungi powder. You can also purchase  seed with “inoculants” like endophytic grass seed (Speares Seed) . Your aim is to increase microbial diversity that helps feed the lawn so you get really good root development which can help the grass plants withstand all kinds of pressures, like drought.

Lawn maintenance

Compost: Add ¼ inch good quality compost to your soil each year, ideally in the fall (can be spring too) to enable the grass to develop a root system that will tolerate the stressful summer months.

Water: A healthy lawn needs ¼ inch water per week. In the hot summer months grass will go dormant but the water will keep the soil microbes alive. These in turn will support the lawn as it breaks dormancy.

Mowing: Keep your grass relatively long like 4.5″. Ensure your lawn mower has sharp blades and never mow more than 1/3 of the height of the plant – from 4.5″ to 3″. Remember mowing is like pruning. Mow when your grass needs it, not on a schedule, and leave the clippings (organic matter on which the soil microbes will feed ).

Soil remediation – compost tea

If you would just like to remediate your soil/lawn and you are unable to get compost, you can also use compost tea. While there is some controversy, it can be effective if you make and use it correctly.

“Lawn tea sommelier” crash course

What is Compost Tea?

First off, compost tea is a microbial inoculant. It is an all-purpose aerated solution made from quality compost (healthy & diverse) teaming with billions of beneficial microorganisms. It contains soluble nutrients including a diversity of bacteria, fungi, protozoa & nematodes. It can increase biodiversity of microorganisms both in depleted soil and on plant surfaces.

Compost tea is not:

  • something you steep.
  • a fertilizer. In Canada Fertilizers are legislated and there are specified minimum amounts of Nitrogen, Potassium and Phosphorous.
  • a pesticide. It won’t “cure” a diseased lawn, but beneficial organisms may prevent problems by outcompeting disease organisms. A rich diversity of healthy soil ecosystem prevents the over population of any one microbial species (think biodiversity below ground not just above).

It is different from and more diverse than AEM (Activated Effective Microorganisms) . Note AEM is a fermentation whereas compost tea is an aerobic process.

Compost tea recipe


Recommend a 5 gallon (20 L) pail brewer system. It is specially designed to aerate and circulate water which prevents dead zones which can result in harmful anaerobic microbes proliferating.


  • Sweet smelling good quality aerobic compost – ideally, use your own plus about 50% vermi-compost
  • Unsulphured molasses
  • Kelp
  • Humic acids
  • Rock dusts
  • Fish Meal
  • Water (ideally well water, or allow chlorine to dissipate by leaving water to sit overnight)


  1. Place about 3 – 4 cups of compost mix into a fine mesh bag (comes with the brewer system)
  2. Insert into pail on frame to suspend in water
  3. Turn on pump to circulate oxygen for aerobic bacteria
  4. Leave for 24 to 36 hours depending on the number of microbes present in the compost, the temperature and the food sources. (Experiment – compost tea will be a little different every time!)
  5. Use tea right away up to 6 hours after stopping aeration. The tea can’t be stored well as food resources are used up and microbes reach maximum concentration then start to die.
  6. Dilute approximately 1 to 10 times – This ratio is difficult to get super standardized as compost has many variables.
  7. Apply
    • Foliar spray provides nutrients directly to leaves. Rule of thumb; use 5 gallons of tea / acre – More for larger plants / trees. Aim for 70% coverage on leaves upper and lower.
    • You can also spray on poor soil to help inoculate it with healthy microbes.

Know that working with living systems takes time and working with “live organisms” takes practice and experimentation. To develop a healthy balanced soil can take up to three years.

Q and A

Recent repairs in the yard resulted in badly compacted grass and soil – it is almost impossible to dig into soil.  Best way to repair?

Aerate in the fall, pull out plugs, add living compost and water. Top-dress with good quality seed, add a thin layer of compost on top to keep the soil moist and encourage seed germination. A fall application avoids the stress of summer and allows time for the plants to grow and establish themselves before the next dry period.

Where to get a 5 gal aerating bucket system?

The Organic Gardener’s Pantry . This website also has a great deal of relevant information on compost tea.

How does one apply Mycorrhizal fungi to the lawn and to individual plants specifically?

Mycorrhizal fungi are UV sensitive.

Clay coated pellets are available for purchase. These can be broadcast on a dry cloudy day when rain is expected. The rain will wash off the coating and the fungi will be absorbed.

Mycorrhizal fungi powder is also available and can be used when planting grass seed.  Moisten the grass seed, add the powder then scatter on prepared area. Add 1/8th  to ¼ inch compost on top to protect from sunlight and hold water. Seeds will germinate quickly.

What seeds are native grasses?

Wildflower Farm has many different native grasses and lawn alternatives. One example is Fescues. Ideally consider planting a range of grasses. Monocultures don’t exist in nature. Developing an healthy eco systems allows the different plants to work  synergistically. Be patient, it takes time to work out what’s best for your site.

What about lawns for shady sites?

Think of using native ground covers like sedges.

What is the best way to get rid of weeds naturally?

Prevention is best. Keep lawn healthy, have variety of grasses and clover for a thick dense lawn to prevent weeds seeds from landing in. Also, a healthy soil is not what weeds like to grow in. And embrace the odd dandelion – these are pollinator friendly flowers! Wild strawberries are also good ground cover for shade and sun and attract pollinators. Many ground cover plants will grow where grass doesn’t.

What web site is recommended to identify grasses? I notice at least a dozen varieties around my area.

The iNaturalist App is useful to identify native local plants. In general it’s difficult to identify grasses and sedges. The best time to try is when they are in bloom.

How is Daikon Radish beneficial to a soil?

Daikon radish has deep roots which drill into soil…this is why it’s known as the “tiller” radish. It creates tunnels, aerates and allows space for water and microorganisms.

Where can you get Speares grass seed?

Potters sells inoculated grass seed. Another alternative is Conon’s. Visit Rideau Thousand Islands Master Gardener’s website.

My grass is all thin and dead-ish, what is your advice on over-seeding?

First question, why is your grass looking this way. Perhaps a two pronged approach is the wisest. First take care of the soil biology – add compost. Then over-seed bare or thin patches with good quality seed (diverse grasses). Don’t mow to short and water regularly. Best time to start all this is in the fall.

I have ground bees with one nest hole, that over the last 3 years has grown to 7 holes.  Do you know about the behavior of these bees?  Do they continue to grow their nests?

Could they be green sweat bees Joyce asks?

“These are solitary bees, meaning they nest alone. They dig burrows deep in the ground to lay their eggs. Sometimes these nests are communal, where a burrow entrance is shared by a group of females. Each female branches out from the entrance to create her own tunnel where she nests alone and takes care of her own young. The responsibility of guarding the main entrance is shared among the group.” They are important pollinators of smaller flowered native plants.

From what I read, if they are sweat bees, it doesn’t sound as if they should ever take over an area. If you really don’t want them all you need to do is increase the density of the vegetation as they dig their homes in bare ground or areas with sparse vegetation. If the grass is thin, with small bare patches, you could take the measures suggested by Astrid to strengthen your grass or plant into your grass some small ground covering plants that are good grass companions (clover, wild strawberry, barren strawberry, violets, self-heal…). 

Here’s a great guide to the Bees of Toronto. It does seem that some sweat bee species are social. See page 24 for a great description of the social behaviour of one type of sweat bee which may be what you’re seeing.

“Societies with a mother queen and worker daughters are called eusocial and this type of organisation is found in honey bees, bumble bees and many sweat bees. Bees in which the only societies are semisocial, i.e. made up of workers that are sisters of the queen, are rare. The Northeastern Augochloropsis may have this type of society. However, quite a few eusocial sweat bees have colonies that sometimes start with a group of sisters with one of them, usually the largest, becoming the queen whose hard working sisters rarely survive long enough to see their nieces become adults.”

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Happy gardening!

Reporting by Colette McKinnon, Master Gardener in Training, Rideau 1000 Island Master Gardeners