As the cold draws to a close, so does the fireplace. It’s getting about time to shut the doors on that old chestnut and move outside for the warm weather, sunshine, and glee. But, before we go, we should consider cleaning up all that wood ash because, fortuitously, the garden would really appreciate those winter scraps.

Well, before we get ahead of ourselves, we should note that, while wood ashes can be fantastic additions to gardens (and compost), they aren’t always the answer. Using wood ash can come with great benefits, but it can also cause a few issues if done improperly. Luckily, it’s not too difficult to decipher.


What’s more is that we need to acknowledge that not all ash is created equally. While wood ash can be a good thing for the garden, that doesn’t mean charcoal briquettes from the barbecue pit or ashes from those fake logs should be put under the tomatoes. We’ll just stick to regular old wood ash for now and figure out how that works.

Understanding What Wood Ash Contains


Unlike other former plant material, such as rotten veggies or grass clippings, wood ash has no nitrogen. Nitrogen is the fuel of the garden, the main component of fertilizer. However, what wood ash does have plenty of is other useful soil additives, such as phosphorus and potassium, the PK of NPK fertilizers. It also has calcium, boron, and other elements that go into making an all-around healthy plant. In other words, ash is fantastic at supplying a lot of the overlooked nutrients that plants ought to be getting.

Understanding the pH of Wood Ash

As most of us know, a balanced pH level is 7. Gardeners are generally aware that most vegetables and fruit plants like a mildly acidic soil level, somewhere in the 6.2 to 6.5 range. Wood ash, however, is alkaline, raising the pH number. Typically, soils are acidic, but in some cases, say, where limestone has been, the soil might be alkaline. Ashes shouldn’t be added to alkaline soils, as a high pH level will begin to lock up nutrients and make them unavailable to plants. Acid-loving plants like blueberries and potatoes probably won’t be great ash fans either.


Where and When to Use Wood Ash

Though it’s not perfect for everything in the garden, wood ash is simply fantastic for many things. This is why slash-and-burn techniques for growing crops have been around for centuries. Periodically adding wood ash will help soil rejuvenate, and adding it at the right time can give nutrient boosts that provide better harvests.

Wood ash can be added to lawns. It works great around the bases of trees, especially hardwood trees or fruit trees. When fruiting plants begin to flower, it will provide them with a boost of potassium that’ll increase crop quality, especially with tomatoes. If garden soil is acidic, particularly below 6.0, it’s good to add a little wood ash to help with pH level and add nutrients.

How to Use Wood Ash


Wood ash isn’t something to add in huge quantities. When working with soils, it’s better applied as a light dusting or a sprinkling, which is typically watered in. This would be the case when amending garden soils, adding it to lawns or feeding trees. When working with flowering vegetable plants, many people like to make a tea out of the wood ash and water the plants weekly with the tea. When using it in a compost heap, small amounts of ash are fine for a new pile, but it shouldn’t be added to mature piles as it will raise the pH level.


A Final Word on Wood Ash

Wood ash is definitely something to take advantage of if there is a free supply. However, it’s important to know where it comes from. Treated woods and fake logs (try these homemade newspaper logs) have chemicals that wouldn’t be appropriate for the garden. Look for natural sources and feed your organic vegetables with it.

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