Nevada County Picayune and Gurdon Times Newspaper Archive

Fireplace Ashes Have Uses In Small Gardens

by Richard Maples

Extension Communications Specialist

WOOD ASHES PROVIDE A

Ashes left over from burning logs in the fireplace or tree limbs in a brush pile can provide some of the fertilizer nutrients your flowers or garden vegetables need, but probably not all, according to Dr. Stan Chapman, soils specialist for the Cooperative Extension Service, University of Arkansas.

"Wood ashes were among the first fertilizers ever used," notes Chapman. "You shouldn't have any problems as long as you don't apply too many ashes and the wood you're burning hasn't been treated with a preservative, such as arsenic or boron," says Chapman.

"You should know where the wood is coming from. If you burn old fence posts or lumber, you may be burning treated wood."

Chapman said an application rate of 50 pounds of ashes per 1,000 square feet of garden or flower bed should be safe. But don't expect the ashes to provide all of your plants' nutrient needs.

"Burning concentrates all of the wood's minerals except nitrogen," Chapman said. "What you get is a salt that accounts for about five percent of the wood's weight. This residue contains phosphorus, potassium, calcium -- but not enough to meet all your plant's fertilizer needs.

"Ashes are a relatively weak source of fertilizer and burnt lime," he continued. "It would probably take 10 times the amount of ashes to equal regular agricultural limestone. The ashes are quick reacting, but not very strong compared to commercial fertilizer."

Chapman said the main danger of fertilizing with ashes is that you may create a salt problem. "You could sterilize your soil. Nothing would grow until the mineral is leached out of the soil or diluted by rainfall. The same is true for boron or arsenic.

"It's the dose that makes the poison, so don't over-apply ashes to your garden or flower beds," he said.

Chapman added that because ashes are a liming material that reduces soil acidity, you don't want to apply them around acid-loving plants, such as azaleas, blueberries and gardenias. "You could make the soil too alkaline and possibly create an iron deficiency."

For more information about fertilizing plants, contact your county office of the Cooperative Extension Service, University of Arkansas.