The purpose of the present invention is to establish a technology that enables individuals who do not have any special knowledge regarding soil to easily obtain soil that is rich in microorganisms in good balance and is suited to growing plants. This kit for producing a plant growth medium is provided with a base medium 1 comprising organic matter and a microorganism-containing capsule 2 serving as a packaging container comprising microorganisms. The plant growth medium 3 is produced by adding the microorganisms included in the microorganism-containing capsule 2 to the base medium 1.
