September 30, 2023

Most garden plants will bounce back after being exposed to smoke and ash. How to take care of them

Smoke from hundreds of wildfires burning across Canada this week has affected air quality in parts of the eastern U.S., a problem all too familiar in many western states. In the suburbs of New York City where I live, the sky turned smoky and orange, for a time categorized by control agencies as “dangerous.”

During the worst, I wore a mask in the house and kept my dog ​​indoors most of the time.

But my plants were in the garden and had no choice but to breathe the poisonous air through the tiny pores in their leaves.

Of course, if your area is heavily affected by smoke or ash, the first priorities should be the safety of people, homes and pets. But after you secure those, you may find that your plants need a little help too.

“If exposed to smoke particles for a short period of time, plants will bounce back, but a large amount of smoke is something other than a transient event,” said Oregon State University Extension horticulturist Brooke Edmunds, who is also a plant pathologist.

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

Pollutants and particulate matter that land on your plants can block sunlight, which is essential for photosynthesis. Decreased photosynthesis translates into reduced energy, and weaker plants will show slow growth and reduced vigor.

In addition, with prolonged exposure, volatile organic compounds in smoke can corrode leaves and other plant parts and interfere with plants’ ability to absorb nutrients. Any damage will not be immediately noticeable.

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

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

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

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

Ash deposits can affect soil chemistry, raise pH levels and reduce nutrient availability for some plants, especially plants that require acidic growing conditions. If you find more than ash in your yard after a bushfire, take a soil sample to your local extension service for testing and advice.

And if you live in a region prone to wildfires, plant less vulnerable varieties that are more resistant to future exposures. Native plants are generally more resilient than exotics. Your extension service, botanical garden or horticultural society can guide you in selecting suitable plants for your area.

“Often people worry about edible plants, but smoke doesn’t really penetrate fruits or vegetables,” Edmunds said. If they have a layer of ash on them, she recommends washing them with a solution of 1 part vinegar and 9 parts water, or peeling them off.

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


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


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