Bupleurum (the yellow umbels), growing in Amdo, China.

      Some soils are stony, or have stony layers. Provided that the water table is not too high, stones help to improve aeration and can be a helpful source of minerals for the soil as they weather. Large stones can however make cultivation or the harvesting of root crops more difficult. If you are planning mechanized cultivation and harvesting on your land you may need to consider some stone removal. This is not usually necessary for herb growing on a small scale. If you find yourself with a particularly stony area, you can make the most of it by growing alpine plants or those that require very free-draining conditions such as Pulsatilla (Pulsatilla vulgaris), Bupleurum (Bupleurum chinensis), Arnica (Arnica montana), and Gentians (Gentiana spp.).

      If you have a large site, differences in the soil profile in different parts of your growing area may help you to decide which species to grow where. While over time most cultivated sites move towards more versatile cropping, it is usually much better to let the choice of species be influenced by the soil conditions than to have a very fixed idea of what you intend to grow where. If you try to mould a site to your theoretical plans rather than working with it, you could find yourself expending a huge amount of energy and resources in trying to adapt the conditions to fit. The influence of varied soil types on your plot is a perfect opportunity to cultivate acceptance as well as to cultivate herbs. If you are lucky enough to have a medium-textured well-drained soil with a neutral pH, you will be able to grow pretty much any herb that you want, where you want.

      Slope and aspect

      It is easiest to manage a herb-growing area that is level or nearly level, but if you have a steeply sloping site, that need not be a negative attribute – it can be useful. Slopes lend themselves to the creation of different habitats; for example, you can create areas to grow wetland plants at the base of the slope and areas for plants that need warmer soils and more sunshine at the top. In temperate climates with high rainfall, provided the soil is free-draining and you can replicate woodland conditions, it may be possible to grow scarce woodland herbs that require free-draining, shaded conditions. Species to consider include Golden Seal (Hydrastis canadensis), Beth Root (Trillium erectum), and American Ginseng (Eleutherococcus senticosus).

      South-facing sites will have more sunlight and will tend to get warm more quickly in the spring. If you are growing aromatic herbs for their volatile oil content, you will find that south-facing sites will be preferable. North-facing sites can be better for herbs that prefer cooler, moister conditions. Although they receive less sunlight, they are less prone to drought and the burning-off of crops.

      As cooler air sinks below warm air, sloping sites can influence the likelihood of frost damage in cooler climates. In winter, icy air tends to gather and stay in the lowest part of your garden. The longer this icy air stays, the more frost damage will be inflicted on your plants. Frost pockets are areas where frost collects but cannot escape: a low-lying hollow or an area at the base of a slope by a wall, for example. When planning your herb garden, it is a good idea to pay attention to where frost lingers the longest. See if there are frost pockets, and either choose these areas for hardy crops or plan a means for the cold air to flow out rather than be trapped there.