We may earn revenue from the products available on this page and participate in affiliate programs. Learn More ›. Adding fresh or composted manure to your flower, herb, or vegetable beds is one of the best ways to improve your soil and grow an organic garden on the cheap. Manure contains nitrogen, potassium, and other micro- and macro-nutrients that plants crave, but it also enhances soil structure, increases water retention, and boosts the activity of beneficial microbes and earthworms. However, if you want to use manure for plant and garden health, timing is everything.