Assume you are talking about the regular garden sage, salvia officianilis. That is the one you use for most recipes requiring sage leaves. Not knowing your climate but basically best choice for planting is outside, morning or partial sun, sandy soil, good drainage as it despises “wet feet”. No fertilizers at all, herbs are generally regarded as “beneficial weeds” so keep in mind what you do to weeds to make them grow. Do the same with herbs.

Repotting generally does stress a plant however if the plant was not well rooted to start with then anything will stress it. When you buy an herb look for roots coming out bottom of plant. What matters is what is under the dirt, not on top. Good root structure is the best indicator of success and the structure is found by observing the roots exiting the container.

Good luck.

Herbanite Bob