Home gardeners often ask whether wood ash can be used as a fertilizer in vegetable and flower beds, around landscape trees and shrubs, and on lawns. Ash can be a valuable source of certain nutrients and can also change the pH of the soil. However, it must come from an appropriate source and its use should be based on the recommendations of soil fertility tests. What is wood ash good for in the garden? Read on to learn important information to help you strengthen your plants naturally.
What are the benefits of using wood ash?
Wood ash contains nutrients that can be beneficial for plant growth. Calcium is the most common plant nutrient found in wood ash and can make up 20% or more of the content. Potassium (also called potash) is another common component of ash, found in concentrations of up to 5%. Magnesium, phosphorus and sulfur are also usually contained in ash in concentrations of up to 2%. Finallycan wood ashContain traces of iron, aluminum, manganese, zinc, boron and other nutrients required by plants.
In addition to its nutritional content, ash can help neutralize soil acidity. When wood is burned, large amounts of carbonates are formed. Carbonates react with the acid in the soil and neutralize it, increasing the pH of the soil. The carbonate content of wood ash (and therefore its acid-neutralizing properties) depends on the type of wood burned and the method of combustion.
What are the possible disadvantages?
Occasionally, even the best wood ash can contain heavy metals like cadmium and lead. However, the content of these metals can be minimized by careful selection of the wood burned to produce the ash. Additionally, the increase in soil pH associated with the use of wood ash reduces the likelihood that plants will absorb heavy metals.
When ash is used in recommended amounts, heavy metal concentrations should be low enough to not pose a threat to plants, animals, or people who eat crops grown on the treated areas. Because the use of ash tends to increase soil pH, application is unlikely to be beneficial in areas where acid-loving plants (e.g. blueberries, azaleas/rhododendrons, birches, red maples, English oaks) grow. TheUse of wood ashcan even be harmful and contribute to problems with chlorosis.
Additionally, many vegetable and other landscape plants prefer slightly acidic soils, so wood ash should be used carefully when growing these plants. Finally, increased pH due to the use of ash can promote certain diseases in some cases. For example, potatoes grown at a higher pH are more susceptible to potato scab
What type of ash should I use?
If you choose to use wood ash in your gardening, you should only use ashes from trees grown in natural areas. DO NOT use wood ash that comes from trees grown near industrial sites, in soil that may be contaminated with toxins or heavy metals, or if you do not know the origin of the wood you want to burn. Also, DO NOT use ash from burning treated wood.
Sift the wood ash before use to remove large pieces of charcoal and active embers. Apply only the amount of wood ash recommended based on a soil fertility test and the nutrient needs of the plants you plan to grow on the treated area. Application of excessive amounts may result in nutrient toxicity and/or nutrient deficiencies in plants. During the winter, spread the wood ash evenly over the area to be treated (e.g. vegetable bed, perennial flower bed, lawn or other landscape area).
Since the ash particles are very fine and can easily be blown away by the wind, you should not spread them in windy conditions.Bring wood ashif possible on moist ground. Where possible (e.g. in a vegetable garden), work the ash into the soil in early spring with a tiller, spade or rake. When working with ash, wear appropriate protective clothing (e.g., long pants, long-sleeved shirt, gloves, safety glasses, dust mask) to avoid exposure that could cause skin, eye, or respiratory irritation.
Plants that benefit from wood ash application
What is wood ash good for in the garden? Ash is beneficial to many plants and shrubs, but some are particularly fond of it. This includes:
- asparagus
- Tomatoes
- Brassicas such as cauliflower, broccoli and Brussels sprouts
- Conifers
- juniper
- Gras
Plants to avoid or limit the use of ash
Ash is not a good choice for plants that like acidic soil and is not recommended for all plants. As a rule, these are plants, trees and shrubs that prefer acidic soils and a lower pH value. Avoid thoseUse of wood ashat:
- Blueberries
- Azaleas
- Rhododendron
- potatoes
- Stechpalme
