Tips for Handling Ash in the Garden

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The OSU Extension Service warns that the closer your garden is to a house fire, the larger the chance the soil may be contaminated.

Wildfire ash is composed of organic matter, so it acts as a soil fertilizer wherever wind and gravity disperse the ashes and they settle to the ground. However, ashes from burned houses and human-made materials present a different scenario. The Oregon Department of Environmental Quality cautions that ashes from house fires may be contaminated with multiple toxins such as asbestos, mercury, lead, cadmium and chromium. These chemicals can leech into the soil wherever ashes fall.

In most cases, the level of toxins mixing with the soil is minimal, but the OSU Extension Service warns that the closer your garden is to a house fire, the larger the chance the soil may be contaminated. In such cases, they recommend collecting several soil samples from the garden and sending them for testing. Their guide, “Analytical Laboratories Serving Oregon” (available at lists all of the soil analysis services provided by labs in our state. OSU’s Central Analytical Laboratory in Corvallis offers a full complement of soil testing, including analysis for heavy metals, chemical contaminants, soil health and nutrient content. Instructions for collecting soil samples are provided at

If your garden has accumulated a thick layer of ash, it might be a good idea to amend the soil with compost or fresh soil, OSU says.

The Extension Service also provides useful guidelines for cleaning up ash from gardens and handling vegetables and fruit on which ash has accumulated. They recommend wearing a face mask when cleaning ash residue (N95 respirators are best if you can find them), and wearing gloves, eyewear and protective clothing.

Prevent dispersing ash into the air by using a gentle stream of water from the garden hose to rinse off plant foliage and produce. Direct the rinse water to a low-traffic area of the yard, rather than down the storm drain. Spritz large amounts of ground ash with water, and then gently sweep up the ash, seal in a bag and discard.

After rinsing ash from fruits and vegetables outside, they can be soaked in white vinegar (1 part vinegar to 9 parts water) and then rinsed again before eating or storing. As additional safety precautions, the skin of tomatoes, apples and root crops can be peeled off and the outer leaves of leafy greens can be removed.


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Nature's role for wildfires


“Nor shall this peace sleep with her: but as when

The bird of wonder dies, the maiden phoenix,

Her ashes new create another heir

As great in admiration as herself”

— Archbishop Cranmer in William Shakespeare’s “Henry VIII,” Act V, Scene 5

At the close of “Henry VIII,” the king finally has (almost) everything he longed for — a divorce, a new, young queen, and an heir to the throne. If only the baby, christened Elizabeth — were a boy. But the newly instated Archbishop Cranmer, eager to please the king, foretells a day when Elizabeth would hand over her throne to a son:

“Who from the sacred ashes of her honor

Shall star-like rise, as great in fame as she was,

And so stand fix’d: peace, plenty, love, truth, terror,

That were the servants to this chosen infant,

Shall then be his, and like a vine grow to him.”

Archbishop Cranmer’s mentioning of the “maiden phoenix” refers to a mythological bird of ancient Greece, which was said to be born from the ashes of its predecessor. In literature, the phoenix has long been associated with physical and spiritual renewal.

In the aftermath of the recent fire that devastated the city of Phoenix, the town’s namesake certainly inspires hope. (The town was originally called Gasburg but was officially named Phoenix in 1857 by Sylvester Wait, who owned the local flour mill and worked as an agent for the Phoenix Insurance Co.)

According to the phoenix myth, and Archbishop Cranmer, wondrous things emerge from ashes. It’s true that forest fires are regenerative. Fire stimulates new growth by creating openings in the forest canopy. Some conifer species are able to disperse their seeds only after a fire sweeps through and melts the resin off their cones, and the hard-coated seeds of some woodland flowers need extreme heat in order to germinate.

In fact, woodland habitats, as well as oak savannahs and prairies, evolved to rely on fire. In particular, wildfires (or controlled burns) nourish the soil by burning living and dead vegetation on the surface, which releases nutrients such as nitrogen, sulfur, phosphorus and carbon. Much of the nitrogen is lost to the atmosphere as a gas, but other nutrients mix in with the soil.

As I have been working on this column, I’ve watched some rain move in, which I hope will cap off this year’s fire season, and that autumn will be the “maiden phoenix” that rises up from the ashes to soothe our scorched earth and souls.



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