Wood Ash as an Organic Garden Fertilizer

For those with a fireplace or a wood stove, don’t throw wood ashes away – use them as a fertilizer in the organic garden. Wood ash raises soil pH and contains valuable nutrients. When used properly,wood ash can improve soil and recycle a byproduct of wood burning. For the organic vegetable garden, the addition of wood ash adds potassium, a critical nutrient, back into the soil.

Safely Handle and Store Wood Ash

For those with wood burning stoves, wood burning household heat or wood burning fireplaces, collecting the ashes is a messy chore. Keep a dust pan and small broom especially for the chore or special implements sold where you bought your wood stove to scrape and collect wood ashes. One five gallon metal pail holds ashes from about one cord of wood, or about 20 pound of ashes. This is enough to spread over 1,000 square feet of garden or mix into the compost pile.

Always store wood ashes in a metal pail. Store them outside of the house on a cement or dirt area well away from anything combustible. Use a metal lid or cover on the pail and place a weight, such as a rock or brick, onto the pail. While wood ashes may appear to be dry and lifeless, all it takes is one spark to light a fire. That’s why it’s important to keep ashes outside, in a closed metal container, well away from anything combustible including the home, outbuildings, dry leaves, and wood piles.

Using Wood Ashes in Organic Vegetable Gardening

Wood ashes have a high pH and will raise soil pH naturally. What is the soil pH? The pH scale is a scale ranging from 0 (pure acid) to 14 (pure alkaline). Depending on the plant, it will prefer acidic soil, neutral or slightly alkaline soil. Most vegetables prefer a pH close to neutral, around 6.5 to 7.5 or so. To check the soil pH, scoop up about half a cup of soil from several spots in the garden.

Place each sample in an individual plastic container or bag and take it to the local garden center or County Cooperative Extension Office. The professionals can conduct a soil test and determine the pH as well as nutrient levels in the organic vegetable garden soil. They can also make recommendations on which amendments to add to raise or lower the pH or counter any nutrient imbalances in the soil.

Wood ash may be applied directly to the vegetable garden if and only if the soil is acidic. If the soil is already alkaline, the safest use of wood ashes is to mix them into the compost pile to allow them to decompose and blend into the existing compost. They can also be spread directly onto a lawn area at a rate of one pail (20 pounds of ash) to 1,000 or more square feet.

To spread wood ash, choose a calm day without wind so that the ash doesn’t blow back. Sprinkle it on the lawn or garden. The benefit of this organic fertilizer is that it will raise the soil pH almost immediately. Lime, another amendment frequently added to acidic soils to raise the pH, takes weeks or months to alter soil pH. Wood ashes will create a noticeable change in about a week. For organic vegetable gardening, mix the wood ash into the soil at least two weeks prior to planting and only if the soil pH reading indicates it safe to add it. While plants are generally forgiving of soil pH slightly out of their range, they will struggle if the pH is very high or very low.

Wood Ashes as an Organic Fertilizer

Wood ashes contain all the nutrients once found in the wood itself, except for nitrogen and sulfur which are lost when the wood is burned. Potassium is one of the three major elements needed in the garden, and wood ash contains an abundance of usable potassium. They also contain phosphorous and calcium, two additional nutrients necessary for good vegetable production.

When using organic gardening methods, composting or recycling organic material back into the garden adds abundant nutrients and enhances the soil structure. Wood ash is just one of many by products of life that can be added back into the soil, reducing landfill waste and enhancing vegetable production.