Place the Herbs
Now it's time to start filling in all the spaces with a variety of herbs. The herbs chosen for this garden will look and smell great, and they're also very long-lived perennials. First we spot all the plants, or set them in place while still in their pots. After everything has been spotted, we can begin digging.
The vertical center of the knot is a noble bay tree (Laurus nobilis) (Image 1). This herb was grown by the ancient Greeks and Romans and is the bay that is used in cooking.
Rosemary (Rosemarinus officinalis) (Image 2) is a perennial shrubby herb that will live for decades — once it's in the ground, you'll never have to replant it. This upright form of rosemary will form the hedge outside the knot garden and will provide intermediate height.
Two lavender varieties, lavender cotton (Santolina chamaecyparissus) and green lavender cotton (Santolina virens) (Image 3) are of similar stature but vastly different colors. Since the key to knot gardens is to use highly contrasting plants against one another to emphasize the geometry you've created, these two work beautifully together in such a setting.
East Friesland meadow sage (Salvia nemerosa 'East Friesland') (Image 4) was a popular perennial, but is too tall for this application. A new variety is perfect for knot gardens, however: it stays very low, produces perfectly sized little flower spikes and is very fragrant. This herbaceous perennial prefers good drainage and drier soils.