Gardening Under Skies of Smoke

Two years ago I woke up and decided to have my early 30’s crisis. I resolved to run a marathon despite having no prior history of outstanding athleticism. Despite a history of mild asthma and overall laziness, I dove into a training plan, and my mileage increased steadily. That’s when the Canadian wildfires started and those long runs to become healthy seemed to have the opposite effect from the pollutants in the air. It made getting outside difficult, which is a special kind of punishment in the Midwest, where we only have so many good days of weather before winter returns.

Now, we’re still dealing with the smoke from Canadian wildfires and it is certainly affecting my desire to be out and building my garden. I’m compelled to find a way to nurture myself and my garden through this episode of smoke, and decided to learn as much as I can about what is happening to our air in the Midwest for us.

The source of the Smoke

The main source of the smoke is our good-natured neighbors to the North. The fires are originating in the Canadian boreal forests, which do have wildfires as part of their lifecycle. Unfortunately, climate change is exacerbating the conditions by creating higher temps and dryer conditions. This has led to “zombie” fires which smolder under the snow, and emerge from the dead in Spring. There are currently over 700 fires burning in Canada, which is leading to our skies of smoke.

Health & Air Quality Alerts

While the haze is fairly easy to spot visually, we have been getting multiple alerts to limit outdoor activity in the Midwest, particularly if you are in a sensitive group. It’s been a rough five years for asthmatics between infectious respiratory diseases and now wildfire smoke. I use Weatherbug on my phone to check for air quality alerts and I also found this website to check for air quality alerts.

Effects on Plants and Gardens

Since this is a gardening newsletter and not just a repository for my complaints about the air quality, we should explore how this affects plants. It’s easy to assume that the smoke in the air will harm our plants, but in reality some low levels of smoke can actually help plants by depositing nutrients. As with most things in life it is all about moderation, and if you are noticing a building on the plant leaves you can rinse them off with a hose. I’d recommend doing this in the morning so it has time to dry off before getting cooked in the mid day sun.

For some plants, the Ozone associated with smoke and fires can cause some stress symptoms, so keep an eye or for chlorotic flecks on leaves. (I have some on my Hydrangea’s and I wonder if this would be the culprit.)

Practical Tips

Wildfire smoke is more of a concern for our health than the plants. It can cause burning eyes, runny nose, chest pain, fatigue, coughing, difficulty breathing, and a rapid heartbeat. If the AQI is higher than 151 it is recommended to wear an N95 mask at a minimum. These should be treated as disposable and be replaced after 8 hours of use. This article from University of Minnesota Extension has more information on the health aspects.

Essentially, if the smoke is bad and you have stuff that must be done, then you can wear an N95. If it is not essential, then try not to spend too much time outdoors and wait until the air clears.

Outlook

While the daily smoke levels depend on weather events, it is likely that the wildfire season will last into early fall or possibly October. The smoke should ease up in the Midwest in fall when temperatures drop and we get our fall rain. Keep an eye out for bad days and try to do your best to avoid heavy gardening days when the air quality is particularly bad.

This Weekend in the Midwest Garden

Wash ash off plant leaves: Rinse plant leaves in the morning if they have collected ash over a smoky Summer. It’s best not to water leaves mid day because they can get burnt from the sun. I also prefer not to water leaves at night because the leaves stay wet too long, which foliar pathogens like powdery mildew love.

Sow native seeds: We’ve had a pretty wet and humid Summer. We can take advantage of this and sow some quick germinating native seeds like Blue Vervain and Monkey Flower.

Deadhead Spent Blooms: Now is a good time to deadhead blooms to encourage more growth. However, consider leaving some or all of the seed heads as a food source for birds if you don’t mind the look of dried seed heads.

Plot Notes

I spent last weekend at a lake house on Petenwell Lake in Wisconsin, so I did not spend much time gardening. The lake house was beautiful and had a few native plants planted. The coolest part was walking to the shoreline and seeing one of my favorite native plants Sweet fern (Comptonia peregrina) growing wild. This is not a true fern, but it is great for covering slopes and smells really nice.

The water lilies did arrive yesterday! Going to let them settle in and then I will share some photos! Some have just been chucked in a bucket, but I did get the Izia planted.

What I Loved This Week

• Read: Nature’s Best Hope - I’m reading through this and it is starting strong. There’s an early chapter covering the work of Aldo Leopold.

• Watch: What makes Dragonflies so extraordinary - Courtesy of the YouTube algorithm.

• Connect: UW-Madison Arboretum - Helpful for learning about local events like the upcoming Native Gardening Conference on September 14th. They are also hosting a native bee workshop on the 10th if you want to join me in learning about pollinators.

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Until next Thursday,
Ken Welch

About the Author

Ken Welch is a horticulturist and research professional at UW–Madison. He’s drawn to native ecosystems, community gardens, and helping others grow confidence in their craft.

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