Consider compost

Unless you have your own compost pile at home, or perfect garden soil that drains well, buy bagged compost to add to the soil before planting annuals, edibles, and many ornamentals (trees and native plants generally do not need added compost). It’s often sold at nurseries in 1- and 2-cubic-foot bags, and in bulk at garden suppliers. Avoid bagged compost that looks as though it has been piled and stored in hot sun for months—it won’t do much for your soil.