Using Wood Ash to Add Calcium to Your Organic Garden

Do you have a wood stove, a fireplace, or a fire pit? What do you do with all of the ash? If you’re in the habit of shoveling it into a trash bag and putting it in the garbage can, I’ve got good news for you — there’s a better way to recycle them that will benefit your garden.

Hot charcoal

What are the Benefits of Wood Ash?

Wood ash is naturally high in potassium, calcium, boron, phosphorus. Not to mention that it’s also very alkaline. Depending on what you are planting, you may need to lower the pH of your soil to create the ideal soil environment. Flowers like lilies and geraniums thrive in alkaline soil. If you live in an area with naturally acidic soil, you may also need to add alkalizing materials like wood ash to raise your soil’s pH up to a neutral level.

Does my Garden Need Wood Ash?

Very possibly, but before you get excited, do a soil test. If your garden has a pH of 7 or higher, you don’t need it. Wood ash raises the pH in your soil, so if you don’t need it, don’t use it. And those acid-loving plants like azaleas, rhododendrons, and blueberries? They don’t need it. Aaaand, lastly, if you have very young or tender plants like seedlings, I’d skip the wood ash treatment with them as well.

Too much potassium can cause a nitrogen deficiency, so it’s important to monitor your plants when treating with wood ash. Some telltale signs of nitrogen deficiency include pale foliage and stunted growth. If your plants are nitrogen-deficient, it is best to stop all wood ash treatments and use an organic fertilizer high in nitrogen to help restore balance to your soil.

Organic Gardening

Can I Use Any Ash?

No. Only wood ash will do. Ashes from coal, charcoal briquettes, or those faux logs will not cut it. These ashes can be thrown away, as they are of no use in the garden.

How Can I Use Wood Ash in my Garden?

    • Make a wood ash tea. Combine ashes with water, let the tea “steep” for a few days, and strain. The result, after brewing for a few days, is a potassium boost for plants that crave that extra potassium, like asparagus.
    • Sprinkle some on the lawn. Just a light layer will do, then thoroughly water in. If your lawn is needing lime and potassium, sprinkling wood ash is a great way to give your lawn the alkaline nutrients that it craves. Potassium helps your grass build thicker cell walls, which helps strengthen it. This strength comes in handy during times of stress, such as drought.
Keeping Warm
  • Feed your trees. The hardwood trees on your property will thank you forever if you spread a bit of wood ash cheer around their bases in late winter. Steer clear of using wood ash on trees like evergreen and juniper, however, as they require more acidic soil.
  • Compost. Adding some wood ash into your compost can increase the potassium and lime levels present. Decomposing materials within your compost can cause the compost to become acidic, which some plants may love. However, if you are looking to neutralize your compost for neutral or alkaline loving plants, adding wood ash is a great, easy, and organic way to achieve this. Make sure the wood is never treated with any sort of chemicals, as we only want to use organic in the garden. Adding wood ash to your compost comes with a caveat — a little wood ash in your compost pile is fine, but too much will over-alkalize your compost.

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