Gardeners who use banana peels as a plant fertilizer choose them as an organic alternative to synthetic fertilizers. However, most commercial production of bananas employs the use of synthetic chemicals, such as the fungicide chlorothalonil. Since chemicals are sprayed on banana trees and developing fruit, banana peels sustain residual effects of the chemicals. In the mid 1980s, chlorothalonil used by commercial banana growers contaminated nearby rivers and was proven to be toxic to fish, birds and other wildlife, according to the University of Victoria, B.C. Purchasing organic bananas is the answer for the gardener who doesn’t wish to introduce synthetic chemical residues into her plants’ environment.
Worked directly into the soil around landscape plants, banana peels decompose rapidly to release nutrients. They work the same way for outdoor container plants. Rapid decomposition generates heat, however, and this builds up easier in smaller spaces, such as plant pots. Placed too near, this heat can burn the roots of potted plants. In addition, the University of Maine advises gardeners to avoid using bananas, and even banana-scented toiletries, because they attract bees. The “alarm pheromone” released by bees smells like bananas and increases defensive behavior, according to the California Beekeepers Association.
Banana peels offer the same nutrients to houseplants as they do to landscape plants. The University of Maine website says that banana peels are so attractive to German cockroaches that they recommend using them as organic roach bait. Peels also attract fruit flies and fungus gnats, two persistent houseplant pests. Organic plant nutrition may not provide a large enough payoff for the indoor gardener who is unwilling to accept the invasion of uninvited bugs into his home; these populations are often difficult to eradicate.
A solution to using raw banana peels that attract bees, cockroaches and flying pests is by first composting the peels. They are best used in outside composters instead of kitchen composters because of their appeal to insect pests. When peels are thoroughly composted, they can be worked into the soil around inside and outside potted plants without risk of root burn. Drying banana peels in a food dehydrator or in the oven is another option for using peels as fertilizer. However, after the dried peels are incorporated into soil around plants, they are rehydrated after the plants are watered, and may still attract pests.