I have rosemary, tarragon, oregano, sage, parsley, and thyme in a heavy duty stoneware trough outside. When I filled it I made sure that I mixed small aggregate grit and sand with good top soil. After planting the herbs I covered the 'soil' with white Cambridge spar(the stuff used for pebble dashing). The trough is in full sun and I very rarely water it and give it a spring feed with general tomato plant type fertilizer. In a week or two depending on the weather I will cut everything right down to nothing and remove all debris and old growth and leaves. In the 4 years or so that it has been in situ I have only ever had to replace the Parsley, due to a heavy prolonged frost( I now cover it if that event seems likely). It is a joy to have, with little care or maintenance required after the initial effort, for the gift of fresh herbs all summer and most of the winter. Oregano, Thyme and Taragon are brilliant for salads and dressings.