Is Wood Ash Good For Grass? (And Does it Kill Grass?)

Everyone wants to have their front lawn looking lusciously green with grass. It is a perfect place to rest, play with your kids and it soothes the soul, not forgetting the admiration you will have from your neighbors and guests. It is for this reason people end up fertilizing their grass, but did you know you do not need to shop for the fertilizer because it is readily available?

Wood ash has served as a fertilizer, has been used for pottery, compost, and much more. This might not be a new concept for you, but there is a reason why wood ash would do your grass a lot of benefits. This article looks into the relationship between grass and wood ash.

Can Wood Ash Be Used For Grass?

Definitely! The myriad of sources will argue in favor of wood ash for grass because of the potassium properties, but the greatest potential benefit to lawns comes from the high levels of alkalinity present in the wood ash. Wood ashes have properties similar to lime products, primarily used to raise the pH of the soil.

Lawn grasses generally prefer slightly acidic soil in the 6.0 to 7.0 pH range, but high-nitrogen fertilizers tend to lower soil pH over time. Many homesteads and soils tend to have slightly acidic soils and when the soil’s pH drops below 6.0, it limits the ability of plants to take up essential nutrients, including nitrogen, phosphorus and iron.

When this happens, the lawn’s beauty, health and resilience suffer. If your soil is acidic or potassium-deficient, wood ashes can help your grass to grow.

However, some precautions have to be taken before and during the application of wood ash for grass. First, it is important to note that wood ash fertilizer is best used either lightly scattered, or by first being composted along with the rest of your compost.

This is because wood ash will produce lye and salts if it gets wet. In small quantities, the lye and salt will not cause problems, but in larger amounts, the lye and salt may burn your plants. Composting fireplace ashes allows the lye and salt to be leached away.

Secondly, not all wood ash fertilizers are the same. If the fireplace ashes in your compost are made primarily from hardwoods, like oak and maple, the nutrients and minerals in your wood ash will be much higher. If the fireplace ashes in your compost are made mostly by burning softwoods like pine or firs, there will be fewer nutrients and minerals in the ash.

Does Wood Ash Kill Grass?

Generally, wood ash should not kill grass, but if the application is not done correctly, it can kill the grass. Wood ash contains lots of micronutrients that are good for the soil, including lots of calcium. Calcium causes the wood ash from fireplaces and stoves to be highly alkaline with a pH of about 9 or higher, depending on the type of wood burned.

High alkalinity is not necessarily bad, but you must be very careful before spreading wood ash on your lawn. The significant majority of our soils are slightly acidic, which is why when the wood ash is added to adjust the pH, the result is a pH closer to neutral, making it best for grass. However, if the wood ash is added to soils that are alkaline already, it has the potential to kill or damage your law.

As such, before applying the wood ash, be sure to perform a pH test on the soil. If you apply lime or spread wood ash without doing a soil test first, you run the real risk of making your soil too alkaline, which could damage or kill your lawn. The recommendation to beat is running an annual soil test to monitor the chemistry of the lawn.

The results will dictate if your lawn requires the wood ash, and if so, how much of it. If it does, go cautiously and only spread the same amount of wood ash as you would lime and follow-up again next year with another soil test. The bottom line is, therefore, only apply the wood ash after a soil test has been done to confirm and has confirmed that it has a low pH, requiring the wood ash for adjustment.

Is Wood Ash Good Lawn Fertilizer?

Well, yes and no! suggests that “plants need to be fertilized because most soil does not provide the essential nutrients required for optimum growth” and “by fertilizing your garden, you replenish lost nutrients…”.

The six primary nutrients that are required in large quantities are carbon, hydrogen, oxygen, all from water and the air, and nitrogen, phosphorous and potassium, which mainly come from fertilizers. Nitrogen is the component that is vastly present in most fertilizers, but the unfortunate part is that wood ash contains no nitrogen.

It would therefore be correct to argue that wood ash does not provide any fertilizer value. When wood burns, it gives off all its nitrogen and sulfur as gasses. You can therefore not advocate for wood ash as a fertilizer if what you need most is nitrogen since it contains none.

Luckily, when wood burns, it does not volatilize calcium, magnesium, potassium and other trace elements which are equally important in a fertilizer. Wood ash is primarily known for containing potassium, which is beneficial as it helps promote root growth in plants.

Potassium also improves the overall vigor of the plant, helps the plants make carbohydrates, provides disease resistance and also helps regulate metabolic activities. Therefore, if you are going for fertilizer because of its potassium elements, wood ash will be the best of them all.

Nonetheless, it is important to note that you should not spread the wood ash if your soil is acidic, or if you are fertilizing acid-loving plants. For instance, keep away the wood ash from blueberries, azaleas, gardenias, rhododendrons and mountain laurel, among other plants, as the wood ash, being alkaline, will slow the growth of the plants.

Also, note that the nutrients in and volume of wood ash depends on the type of wood that is burning. Hardwoods produce about three times the ash and five times the nutrients per cord as softwoods.

Is It Ok to Put Wood Ash in The Garden?

It is very okay to put wood ash in the garden. Wood ash is vital for the garden as it helps control pests. The salt in the wood ash will kill bothersome pests like snails, slugs and some kinds of soft-bodied invertebrates.

As previously mentioned, wood ash is also helpful in the garden as it helps change the pH of the soil, making it ideal if you are growing neutral-based or alkaline-loving plants. Wood ash also provides potassium that is very vital to plants, for several reasons, including promoting root growth.

However, several precautions should strictly be adhered to:

1. When controlling pests

Sprinkle the ash around the base of plants being by soft-bodied pests. However, if the ash gets wet, you have to refresh the wood ashes as the water will leach away the salt that makes wood ashes an effective pest control.

2. Do not use contaminated ash

It is possible that while you were burning the wood for the ash, you introduced trash, coal, cardboards or pressure-treated painted or stained wood into the fire. These materials contain potentially harmful substances, which could leech the harmful products into the ash and subsequently into your soil and plants.

For instance, the glue in cardboard boxes and paper bags contains boron, an element that can inhibit plant growth if found in excessive levels.

3. Do not use with potatoes

You should not use wood ash where potatoes are to be planted. this is because it encourages scab disease. The same applies to when you use it on acid-loving plants like conifers, mountain laurels, camellias, oaks, strawberries, cranberries, blueberries, azaleas or rhododendrons.

4. When applying the wood ash

Do not scatter the ashes in the wind, as aside from affecting your eyes and inhibiting proper breathing if they are blown towards you, the ashes could scatter into acid-loving plants.

These plants do not like the alkaline conditions created by the wood ash and could result in low production. Therefore, apply the recommended amounts gently and more preferably, to moist soils and then rake lightly to mix.

5. Do not leave wood ash in lumps or piles

If you concentrate wood ash in one place, the excessive salt from the ash will leach into the soil and create a harmful environment for plants. Therefore, spread it evenly and never live the wood ash in piles.

6. Application during seeding

Never apply wood ash at the time of seeding. This is because ash contains too many salts for seedlings and could potentially damage their seeding process. Therefore, apply it either when preparing the land or garden before planting, or after the crops or plants are a bit developed.

7. Mixing with nitrogen

We have learned that wood ash contains no nitrogen, while other fertilizers do. This could tempt you to mix the two for the proper addition of nutrients to the soil or apply the two simultaneously. Do not do this! If you add wood ash with nitrogen fertilizers like ammonium sulphate, urea or ammonium nitrate, the fertilizers will lose their nitrogen content.

When ammonia gas is mixed with high pH materials such as wood ash, the nitrogen is lost. For proper application, wait at least a month after wood ash application before applying nitrogen fertilizer. This will allow time for the soil to reduce the alkalinity of the wood ash.

Which Plants Like Wood Ash the Most?

There is a myriad of plants that love wood ash. They include garden plants like artichokes and tomatillos, greens like collards and arugula, and brassicas like broccoli.

Also on this list includes lavender, candytuft, garlic, Boston Ivy, onions, Hosta, hydrangeas, maiden grass, lettuces, wild red columbine, and stone fruit trees, among others. They thrive in alkaline conditions, making wood ash their friend. However, there are three general types of plants that love wood ash:

1. Plants in overly acidic soils

Some plants can thrive in acidic soils, although some require a raise in the pH to survive. Artichokes, tomatillos, collards, arugula, and broccoli require alkaline soil for optimal health.

2. Plants overrun by disease and pests

Wood ash keeps various pests at bay and is vital for such plants. Brassicas like broccoli and cauliflower are commonly affected by clubroot disease and they would really love the addition of wood ash.

3. Plants with potassium deficiencies

Potassium is vital for healthy flowering and fruiting and strong roots. Potassium-0deficinet plants appear as brown or with discolored leaf edges and would benefit from some wood ash which adds the potassium they require into the soil.


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About Rinkesh

A true environmentalist by heart ❤️. Founded Conserve Energy Future with the sole motto of providing helpful information related to our rapidly depleting environment. Unless you strongly believe in Elon Musk‘s idea of making Mars as another habitable planet, do remember that there really is no 'Planet B' in this whole universe.