Growing peppers. Peppers hate nitrogen/commercial fertilizer. Wait until plants flower before fertilizing. Then spray leaves with 1 tsp of Epsom salt to 1qt of water (peppers need Magnesium to set fruit). Peppers also enjoy small amounts of potassium (wood ashes).
Plant BFFs. Marigolds help tomatoes and roses grow better. Nasturtiums keep bugs away from squash and broccoli. Petunias protect beans from beetles and oregano chases them away from cucumbers. Geraniums keep Japanese beetles away from roses and corn. Chives make carrots sweeter, and basilmakes tomatoes even tastier.