Winter is the time of year we collect ashes, but what do we do with them? Do we add them to the compost pile? Do we apply a light dusting on the soil? Do we store them for the next growing season?
Research was required and here is what I found:
A cord of firewood can produce up to 50 pounds of ash depending on the wood. Hardwoods produce 3 times as much ash, and more nutrients than softwoods.
When wood burns, nitrogen and sulfur are lost as gases but Calcium, Potassium, Magnesium and trace elements remain.
Wood ash is a valuable liming agent, raising pH, thus neutralizing acid soils, therefore acid loving plants like blueberries, cranberries and strawberries will not benefit from the addition of wood ash. However, wood ash is especially good for breaking down pine needles, oak leaves or wood chips
The best time to apply wood ash is in the Spring when the soil is dry, because of its fine particle size, it reacts rapidly. The average ash (N-P-K) to 0-1-3 (One reference did suggest adding it in the fall.)
Wood ashes are best stored in a fire-proof container, until they can be moved to another bucket to keep for the next growing season.
Wood ashes can be added to the compost pile in layers. Never leave wood ash in lumps or piles because concentrated wood ash causes excessive salt build-up in the soil through leaching and can be harmful to plants nearby.
For most garden soils, 20 lbs of wood ash (about a 5 gallon bucket) per 1000 sq.ft., can be applied safely each year. That equals about 6 pounds of ground limestone applied to the same area.
Wood ash can repel slugs and snails because it draws water out of these invertebrates. Sprinkle around plants, but once it gets wet it loses it deterring properties. Too much ash can alter pH levels in soil. Use carefully.
Wood ash can be added to the hole when planting tomatoes, ¼ cup in the hole pumps up these calcium loving plants and adds potassium (7 – 8%)
Wood ash controls pond algae. 1 Tablespoon per 1000 gallons adds enough potassium to strengthen other aquatic plants that compete with algae, slowing its growth.
Wood ash can be used on fruit trees and root crops
Cautions Included:
Do not use ash from burning trash, cardboard, coal or pressure treated painted or stained wood, to many toxins exist.
Do not scatter on windy days.
Do not mix with nitrogen fertilizers such as ammonium sulfate or ammonium nitrates or urea. These fertilizers lose their nitrogen as ammonia gas when mixed with high pH materials such as wood ash. Leave a month’s time between application of each.
Sources:
Carolyn Herriot, A year on the Garden Path, You Bet Your Garden, Mike McGrath, Master’s Gardener’s emmitsburg.net, Oregon State University Extension Service, Ed Hume Seeds,
