Indoor houseplant fertilizers fall into two groups: water soluble (liquid quick release), and granular, slow release fertilizers. Jack's Classic Indoor plant food works well as a powder for String of Pearls Plants. On the other hand Osmocote Indoor/Outdoor is an option as a granular, slow release fertilizer that can be applied while potting and planting. Any type of fertilizer offers nutrients that help plants with the transition to a new environment.