Which Plants Cannot Tolerate Wood Ash? Gardeners Should Know

Wood ash is a popular eco-friendly fertilizer, but it is far from suitable for all plants. For some crops, fertilizing with ash can slow growth, reduce yield, or even damage plants. Gardeners should know which plants to keep away from ash.

Wood ash is an available and popular natural fertilizer in many Estonian households, containing nutrients essential for plants such as potassium, calcium, and phosphorus. However, this does not mean that ash is suitable for all garden plants – for some crops, its use can do more harm than good.

The main problem lies in the fact that wood ash raises the pH level of soil, making it more alkaline. Plants that prefer acidic soil, such as blueberries, lingonberries, cloudberries, and heather, suffer when fertilized with ash – their growth is slowed and the plants can no longer properly absorb nutrients available in the soil.

It is also advisable to avoid ash when growing potatoes. Higher pH promotes the spread of scab on potatoes, a common fungal disease that damages the appearance of tubers. Onions and garlic also prefer neutral to slightly acidic soil and do not need additional fertilization with ash.

Tomatoes, peppers, and other members of the nightshade family are similarly sensitive to changes in soil reaction. Excessive alkalization can cause nutrient deficiency and stunted growth. Ash is not recommended for use on freshly sown seeds either, as it can interfere with germination.

In summary, wood ash should be used thoughtfully. Before fertilizing, it is recommended to check the soil pH level and research which crops grown in your garden prefer an acidic environment. Ash works well for rose gardens, bulbous flowers, and many vegetables such as cabbage, beets, and carrots – but those plants that prefer acidic soil should definitely be spared from ash.