After light, proper soil is the next most important factor in producing healthy herbs. When roots are confined in a pot or planter, water and air cannot move easily. To improve drainage without sacrificing nutrients, add sharp sand or perlite to a good sterilized compost-based mix. Most herbs do well in soils of pH 6 to 7. Many people incorrectly think that herbs grow better in poor soil.
Flavors are stronger when culinary herbs grow outdoors in gardens.
But in the confines of a pot, supplementary feedings with liquid fertilizer or organic fish emulsion are necessary. Feed herbs once a week when plants are actively growing, but not when dormant. Watering is not a trivial matter with herbs. In general, water less often and more thoroughly, and only when the soil is actually dry. When the soil is dry to the touch, add water until it comes out the bottom of the pot.