As a gardening and landscaping expert, I am here to provide you with a detailed answer to the question: Are walnuts OK in compost?
When it comes to composting, it’s important to be aware that not all materials are suitable for every type of compost. In the case of walnuts, specifically black walnut hulls, nuts, leaves, or bark, it is generally advised to avoid using them in compost piles for vegetable gardens. However, this doesn’t mean that walnuts cannot be used in compost altogether.
The reason why black walnut residue should be kept out of vegetable garden compost is due to the presence of a chemical compound called juglone. Juglone is found in various parts of the black walnut tree, including the hulls, nuts, leaves, and bark. This compound is known to be allelopathic, meaning it can inhibit the growth of certain plants and even be toxic to them.
Vegetable plants are particularly sensitive to juglone, and its presence in compost can have detrimental effects on their growth and health. It can lead to stunted growth, yellowing of leaves, wilting, and even death of the plants. Therefore, it is best to avoid adding any black walnut residue to compost intended for vegetable gardens.
However, if you have a compost pile that is designated for use on turfgrass only, then compost containing black walnut residue can be beneficial. In fact, compost with black walnut residue can be excellent for use on lawns. The juglone in the compost can act as a natural herbicide, suppressing the growth of weeds and providing a nutrient-rich environment for the turfgrass to thrive.
Personal Experience: In my own gardening experience, I once made the mistake of adding black walnut leaves and bark to my vegetable garden compost. Unfortunately, this resulted in the poor growth and eventual death of several vegetable plants. Since then, I have learned the importance of avoiding black walnut residue in compost intended for vegetable gardens.
While walnuts can be used in compost, caution should be exercised when it comes to using black walnut hulls, nuts, leaves, or bark in compost piles for vegetable gardens. The presence of juglone in these materials can be detrimental to vegetable plants, leading to poor growth and even plant death. However, compost containing black walnut residue can be beneficial for use on lawns, as it acts as a natural herbicide and provides nutrients for turfgrass.
