August 2025 Newsletter
August is here with a smoky haze and not much rain. Agriculture Canada says that conditions in the GTA are “abnormally dry” to a “moderate drought”. There is a fire ban in effect in my small town. The lawn is brown and crunchy.
At the same time, my native plants are flourishing. Their roots have tapped into whatever water they can find, even in our sandy soil. Some of the species that prefer moist soil have started to droop in the heat, but a little water and an extra layer of mulch brings them right back. This is the magic that happens when the right plants are in the right place.
Mulch is a key element in this equation. Mulch helps to keep water in the soil, preventing it from evaporating away during hot, dry conditions. As a bonus, mulch also protects roots, reduces the number of weeds and prevents soil erosion. I cannot stress enough how important it is to keep soil covered with a layer of mulch.
What to use for mulch?
The great thing about mulch is that, with a little creativity, it is usually free. No need to go to the store to buy shredded wood chips that have been dyed an unnatural colour. In the fall, collect all the wonderful leaves and stash them in a pile in the corner of your yard, ready to be used as mulch in the spring. Or toss them directly on your beds in the fall. In the spring, grass clippings can be nestled around small seedlings. Use what you have and what works.
The one time that you don’t want to mulch is if you have directly seeded on top of the soil and you are waiting for your seeds to germinate. Many native plant seeds need light to germinate, so wait until the seedlings are growing well to cover the soil. I try to have all of my beds mulched by the end of June, ready for the heat of summer.
I have two main sites where I have seed production beds. At the one site there are lots of trees. They produce a lot of leaves and shelter the site from the wind. I mainly mulch with leaves at this site, because it is what I have and it works well. Pictured below is a bed of Tall thimbleweed (Anemone virginiana) mulched with leaves. I have not watered them at all.
At my second site, a sunny open field, I tried to use leaves and they all blew away. That site has lots of lawn growing on wet, clay soil, so I use grass clippings, which don’t blow away in the wind. Pictured below are New England Aster (Symphyotrichum novae-angliae) mulched with grass clippings. They also have not been watered this year.
Ultimately, you want the leaves of your mature plants to be touching so that they are shading the soil. One of my favorite quotes from Doug Tallamy is: “If you can see the soil, you don’t have enough plants”. You’ll need to leave some space when planting small seedlings, and mulch them well, but once they are full grown they will do most of the work of shading and mulching themselves.
You may hear that grass clippings, wood chips or other mulches leach nitrogen from the soil and harm your plants. The benefits of mulch far outweigh any potential loss of nitrogen. Keep your soil covered!
New Species
We have four new species this month, all of them sedges. Sedges form a wonderful backdrop of green in the garden. You can even use them as a living mulch, planting them in between showier plants. Their grassy foliage stays lush through the summer months as the leaves of the spring ephemerals fade. You might not be familiar with the sedges, but their subtle qualities will win you over once you try them in your garden.
Golden sedge thrives in sunny, dry, sandy locations. Dewey’s sedge, Peck’s sedge and Rosy sedge are all upland forest species that will grow well in woodland gardens.
Happy mulching!
Andrea D’Silva
Swallowtail Native Plants