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Is Wood Ash Good for the Garden? What You Need To Know!

wood ash used in garden

Wood ash contains a variety of nutrients that can be beneficial to certain plants. For instance, this ash includes a high amount of calcium and potassium, which is vital for a plant’s growth. Other important nutrients like magnesium, phosphorus, and sulfur are all present in wood ash as well.

Furthermore, word ash contains a high number of carbonates, which are produced when wood is burned. These carbonates react with the acid in the soil to neutralize it, which causes the soil pH to increase. Some plants love this, but those that prefer acidic soil will not.

The level of carbonates in wood depends on the type of wood and how it was burned since they are only produced during burning. Usually, wood tends to do a 50% worse job at neutralizing acid in soil than commercial options. However, wood ash is free, while other options are not.

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Does the Type of Wood Ash Matter?

The type of wood ash does matter substantially. You don’t want to use just any wood ash, as different types of wood do different things. However, you also don’t want to use potentially contaminated trees, like those grown near industrial sites. These trees may contain pesticides, as well as toxins and other heavy metals.

As you might imagine, these substances can seriously harm your plants.

You also don’t want to use any wood ash that was produced by burning treated wood, garbage, plastic, or other waste. These substances are typically not great for your plants, so they should be avoided.

In other words, you only want to use safe, untreated wood ash—nothing else.

wood ash
Image Credit: Pixabay

When Shouldn’t I Use Wood Ash?

Just because wood ash is readily accessible and includes nutrients doesn’t mean that you should use it all the time. There are many situations where using wood ash would not be recommended in the least.

Often, wood ash will include heavy metals like cadmium and lead. This is made even more troublesome by wood ash’s ability to increase the pH of the soil, which also increases the likelihood of the plants taking in these heavy metals. However, by choosing the best wood ash, you can minimize these heavy metals in your garden.

With that said, if you use wood ash occasionally, the heavy metal content will not be enough to matter. It shouldn’t harm your plants or anything that eats the plants. You can always test the wood ash for heavy metals if you are concerned about it.

Of course, because wood ash raises the pH of the soil, you don’t want to use it in areas with acid-loving plants. These plants may not approve of the wood ash and may grow worse after it is applied. In this way, wood ash can actually be detrimental to certain plants.

In some cases, the increased pH in the soil can also increase the odds of certain diseases. For instance, potatoes are more likely to develop potato scab at higher pH levels.

Therefore, you should only use quality wood ash in areas where the appropriate plants are growing. Some plants will like wood ash, while others do not.

wood ashes in the bucket
Image By: NordHelena, Shutterstock

How Do You Use Wood Ash?

Wood ash is typically pretty easy to use. You can apply it just like any other fertilizer.

Before use, sift the wood to remove any large pieces and charcoal. You only want the fine ash—not all of the other stuff that is mixed up with it. You should only use the wood ash in accordance with the nutritional needs of the plants in your garden. You don’t want too many nutrients, after all.

The best way to determine when to apply fertilizer is to test your soil. Too many nutrients can lead to toxicity or nutritional problems in the plants. Some minerals prevent other minerals from being absorbed, and therefore, it is vital that everything is balanced.

You should plan on using about 15 to 20 pounds per 1,000 sq. ft. every year. Apply it in the winter as evenly as possible by simply sprinkling it on the ground. Because the wood ash is very fine, you should avoid applying it on a windy day as it may just blow away. It is best to apply it to moist soil, as it helps it stick a bit better.

It is typically best to work the ash into the soil. If you’re already turning over the soil, you can work the wood ash into it at this point.

Because it is so alkaline, wood ash can pose a huge health risk. Therefore, we recommend using gloves when you apply it. Protective clothing is also recommended. Consider limiting exposure to skin, eyes, and mouth, and breathing wood ash in can also be damaging.

gardener's hand holding ashes
Image By: Sunny_Smile, Shutterstock

What Plants Like Wood Ash?

We recommend that you use wood ash with plants that like a higher pH. Some of these plants include garlic, chives, leeks, lettuces, asparagus, and stone-fruit trees.

Of course, we highly recommend that you get your soil tested before you apply any fertilizer. If your soil is already suitable, then you likely don’t need to use wood ash. Sometimes, you may not need to use any sort of fertilizer as your soil may already be great.

You should compare the needs of your plants with the current measurements of your soil and use wood ash only if it will help the numbers get closer to what your plants need. It isn’t that wood ash is always helpful—it is just helpful in certain situations.

When Should I Use Wood Ash in my Garden?

The best time to utilize wood ash is when you turn the soil over in early spring. However, this isn’t always possible. In some cases, you may be using wood ash on an area you aren’t tilling. In this case, it’s best to apply wood ash to the top of the soil three to six months before you do any planting.

You want to give the wood ash time to work into the soil, which typically takes a quarter to half a year if you apply it to the top—working it into the soil typically allows it to decay faster. A chemical change needs to occur, which takes a bit of time.

woman palnting vegetable at the garden
Image By: Piqsels

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Wood ash is a great fertilizer for gardens in certain situations. We highly recommend using this fertilizer when you need to increase your soil’s pH or add calcium (and other nutrients) to the soil. That said, we recommend that you test the soil before adding any fertilizer, as wood ash may not be the appropriate fertilizer for you.

If you use it in the appropriate situation, wood ash can be extremely helpful. However, it isn’t always better than other options—it’s dependent on the unique situation.

Featured Image Credit: FotoHelin, Shutterstock


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