The Benefits of Wood Ash in the Garden

Unlike the decomposed remains of leaves and other green plant parts, wood ash doesn’t contain nitrogen. But it has potassium, phosphorus, calcium, magnesium and also contains trace amounts of sodium, zinc and iron. Therefore you can use wood ash as a good fertilizer. But before using it for feed your plants, you must get a soil test done, so you know whether it will benefit you or not. Calcium is the most abundant element in wood ash and gives ash properties similar to agricultural lime which can neutralize acidic soil. Therefore if you are growing acid loving plants like azaleas, rhododendrons, camellias and blueberries, it’s not good to use wood ash for your garden.

Many farmers and gardeners throughout the world use wood ash as a natural soil amendment because it’s created through the combustion of plant materials and contains many of the essential elements needed to support plant growth. However not all types of ashes are good for plant growth, so remember to use only wood ash. Ashes from charcoal briquettes, fake logs and coal contain toxins which can be harmful for your plants. Here are some of the useful things you can do with wood ash in your garden. You should follow the prescribed application rates and use common sense to prevent accidents and avoid environmental contamination.

Add it to Your Organic Compost Pile

Wood ash is rich in potassium, phosphorus, calcium and magnesium. Potassium is an essential nutrient for flowering and fruiting. Plants need phosphorus for energy storage and transfer, photosynthesis, cell division, cell enlargement and respiration. Without magnesium, chlorophyll can’t capture sun energy needed for photosynthesis because magnesium is essential for tree leaves to get their green color and calcium is responsible for holding together the cell walls of plants. Therefore adding wood ash to your compost pile is a free and beneficial way to boost these plant nutrients in it. But you need to add wood ash to your compost pile in moderation because too much of it can raise the pH value of your compost pile.

Neutralize Acidic Soil

If your soil already has a pH of 7.5 or above, wood ash isn’t an ideal addition for your garden. Wood ash can neutralize acidic soil, so if you are growing acid loving plants like blueberries and azaleas, there’s no point in spreading it around your plants. The pH is not an indication of fertility, but it does affect the availability of fertilizer nutrients. Therefore it’s always recommended to conduct a soil test before adding wood ash to your garden.

Make Ash Tea

Curling leaf tips, brown spots, reduced crop yield, slower plant growth and yellowing between leaf veins are some of the signs your plants are not getting enough potassium. You can use ash tea to correct or prevent these problems. Put five pounds of ash in a cloth bag and tie it closed. Then place it in a fifty gallon bucket filled with water for about five days. Once the ash tea is ready after five days, pour a cupful around your plants weekly to increase the potassium content.

Wood Ash for Pest Control

Wood ash is an effective natural pest control. You can use wood ash to repel insects, snails and slugs because it draws water from these soft bodied invertebrates. If you identify your plants being attacked by these soft bodied pests, simply sprinkle wood ash around the base of your plants to control them. Always remember to keep the wood ash fresh around the base of your plants because if the ash gets wet, water will drain away the salt that makes wood ash an effective pest control.

Use Wood Ash to Melt Snow and Ice

Fire place ashes are a natural abrasive and provide good traction in cold conditions. So you can use wood ash to melt ice and snow in moderate cold conditions. It doesn’t damage your trees, shrubs or lawns. It won’t corrode metals and concrete and it’s not harmful for your pets. Therefore you can consider using wood ash to melt ice and snow in your garden than buying rock salt and other chemicals for the same purpose.


Wood ash is the inorganic and organic residue remaining after combustion of wood or unbleached wood fiber. It’s a good source of calcium and potassium for your garden. You can use it to control harmful pests like snails and slugs. Not all wood ash fertilizers are the same. If the ashes are primarily made from hardwoods like maple and oak, minerals and nutrients in your wood ash will be much higher than the ashes made from softwoods like pine and birch. Always remember to keep wood ash dry before you use it, because if you leave your wood ash out in the rain, water will drain away nearly all the useful nutrients and leave you with a fairly useless sludge.

Wood Ash Facts

  • Wood Ash has a liming effect about 30% of the total neutralizing power of lime.
  • Wood Ash is also a good source of phosphorus, potassium, aluminum and magnesium.
  • The largest component of Wood Ash is calcium carbonate.
  • Wood Ash increases the alkalinity of the soil to beneficially affect plant nutrition.
  • Wood Ash contains less than 10% potash, 1% phosphate and trace amounts of micro nutrients including copper, iron, zinc, boron and manganese which are essential for adequate plant growth.
  • Wood ash may contain trace amounts of heavy metals including cadmium, lead, chromium and nickel.
  • Ash from treated timber may contain potentially harmful residues.
  • Wood ash is a great odor remover.
  • Storing seeds in wood ash is effective in both preventing rot and insect predation.
  • Adding some wood ash to your pond can slow down its algae growth.

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