An “herb spiral” garden accommodates for the unique needs of most culinary herbs. Made of stone, cement, brick–or another material with a high heat capacity–the spiral-shaped structure functions to create a series of different microclimates and drainage conditions.
Herbs that prefer dry conditions are planted near the top, where drainage is the best (ie. Thyme).
Herbs and other plants that prefer hot conditions are planted near the walls, where they take advantage of radiating heat at night (ie. Rosemary).
Herbs that prefer sheltered conditions are planted lower on the structure, where they are sheltered from prevailing winds (ie. Dill).
Herbs that prefer cool conditions are planted low on the side of the structure that receives less sunlight (ie. Chervil)
Herbs that prefer wet conditions are planted near the base of the spiral, to where the water drains (ie. Mint).
Right now, my herb spiral contains this baffling array or plants:
Mint (Moroccan, Spearmint, Chocolate, Garden, Water), Thyme (Lemon, Lemon Variegated, Lavender, English), Sage/Salvia (Italian, Purple), Chives (Garden, Chinese, Garlic, and Round-Headed Leek) Curry Plant, Lavender, Rosemary, Tarragon, Oregano, Parsley, Dill, Chervil, Sorrel, Black Cumin, and Coriander.