Many natural substances and byproducts can be useful sources of fertilizer, and hair is no exception. Used as a mulch or in the compost pile, human and animal hair as a fertilizer can actually contribute much-needed nitrogen to the soil. While there are several pros to using hair as a fertilizer, including cost and effectiveness, there are also cons, including the decomposition time and potential problems with chemicals.
The hair that comes from humans and animals is composed of proteins and a significant amount of nitrogen, which plants need to thrive. Some gardeners take the excess hair brushed from a pet or clippings of their own hair and mix it into a compost pile. When the hair eventually breaks down and decomposes, it creates an especially nitrogen-rich fertilizer for the garden. Hair can take a very long time to break down, because of its high protein content, unless the compost pile is kept moist and turned often. This problem can be mitigated somewhat by cutting the hair into one-inch sections or smaller.
Instead of waiting for hair to decompose in the compost pile, some gardeners add it directly to the soil of flower beds or planters as a mulch. Hair works well to help soil retain moisture and keep plant roots hydrated as well as helping to regulate the plant’s temperature. Over time, the nitrogen will be released from the hair as fertilizer for plants, leading to greener, thriving plant growth. It does take a long time for the nutrients to be released from hair as fertilizer, however, so the first plants grown with hair may not be as vigorous as subsequent plantings. Due to this slow-release quality of hair as fertilizer, it might be better to use hair for plants that have a long growing cycle or slower overall growth.
Unlike chemical fertilizers, hair as fertilizer can be very low cost or free. Pet hair is a great source for fertilizer or compost, as is hair from shower drains, hair brushes, and home hair cuts. Local barbershops and hair salons may be willing to give away daily sweepings of hair to be used in the garden. Care must be taken when using chemically treated hair, however, such as hair that has been permed or dyed, as these chemicals can leach into the soil. In analyses of commercially prepared hair mats used in the garden, traces of lead have been found, which are likely linked to chemically treated hair being used.