Bury the peel of one banana in the potting soil for containerized roses. Place the soil with the banana peel below the shrub's root zone. Plant the rose and refill the surrounding space with potting mix. Water the potted shrub until excess runs out of the drainage holes.
Cut two or three banana peels in sections. Dig a hole outside for a rose bush. Drop the banana-peel pieces into the hole. Cover them with a thin layer of compost. Plant the rose bush and backfill the hole with topsoil. Mix banana peels with the soil around the base of the rose bush throughout the growing season. Push small pieces into the ground close to the surface gently to prevent root injury.
Cut banana peels into small pieces. Dig holes in the garden for tomato and green pepper transplants. Place three or four banana-peel pieces on the bottom of each hole to promote strong stems. Plant the seedlings and refill the hole with topsoil. Water each plant to the root zone.