Most garden plants will bounce back from exposure to smoke and ash. How to take care of them

Smoke from hundreds of wildfires in Canada has lowered air quality across swaths of the eastern United States this week, an all too well-known problem in many western states. In the suburbs of New York where I live, the air turned smoggy and orange, for a time classified by surveillance agencies as “hazardous.”

At worst, I wore a mask inside my house and kept my dog ​​mostly indoors.

But my plants stood in the garden with no choice but to breathe in the toxic air through the tiny pores of their leaves.

If your area is heavily affected by smoke or ash, the first priorities should of course be the safety of people, home and pets. But after securing them, you may find that your plants need a little help too.

“When exposed to smoke particles for a short time, plants bounce back, but a heavy amount of smoke is different from a transient event,” according to Brooke Edmunds, community horticulturist at Oregon State University Extension, who is also a plant pathologist.

“It depends on how close you are,” she said. “There could also be a localized effect, where a garden is covered in ash, and half a mile away there’s nothing because that’s how the wind was blowing things around.”

Pollutants and small particles that land on your plants can block sunlight, which is essential for photosynthesis. Reduced photosynthesis translates to reduced energy, and weaker plants will show slow growth and reduced vigor.

Additionally, with prolonged exposure, the volatile organic compounds in the smoke can affect leaves and other plant parts and disrupt the plants ability to absorb nutrients. Damage, if any, will not be immediately noticeable.

The best thing home gardeners can do is “keep an eye on the plants for the rest of the summer and give them TLC as these events can add to overall plant stress,” Edmunds advised, adding that “the most will make it.”

Wash the smoke residue off the plants with a gentle stream from a hose, then give them a long, slow drink to rehydrate them. Do not fertilize until the air has cleared and the plants have fully recovered.

If there are ashes, Edmunds cautions against using a leaf blower to remove them, which would increase the risk of inhalation.

“Always protect yourself as a gardener,” she said.

Ash deposits can affect soil chemistry, increase pH levels, and decrease nutrient availability for some plants, especially those that require acidic growing conditions. If you find more than a dusting of ash in your garden after a wildfire, take a soil sample to your local extension service for testing and advice.

And if you live in an area prone to wildfires, plant less vulnerable species that will better withstand future exposures. Native plants tend to be hardier than exotic plants. Your extension service, botanic garden, or horticultural society can guide you in selecting the appropriate plants for your area.

“A lot of times people are concerned about edible plants, but the smoke doesn’t actually penetrate fruits or vegetables,” Edmunds said. If there is a layer of ash on them, she advises washing them with a solution of 1 part vinegar and 9 parts water, or peeling them.

“It’s really early in the season, so there probably won’t be any issues,” Edmunds said.


Do you have questions about spring gardening? Please send them to Jessica Damiano at with “Gardening Question” in the subject line. She will answer selected questions in a future AP gardening column. Damiano regularly writes gardening columns for the AP and publishes the award-winning Weekly Dirt Newsletter. You can sign up here for weekly gardening tips and tricks.


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