A knot garden is a garden of formal design in a square frame, consisting of a variety of aromatic plants and culinary herbs including germander, marjoram, thyme, southernwood, lemon balm, hyssop, costmary, acanthus, mallow, chamomile, rosemary, Calendula, Viola and Santolina. Most knot gardens now have edges made from box (Buxus sempervirens), which is easily cut into desired shapes, like dense miniature hedges, and stays green during winters when not all of the "filling" plants are visible or attractive. The paths in between are usually laid with fine gravel. However, the original designs of knot gardens did not have the low box hedges, and knot gardens with such hedges might more accurately be called parterres.

Most Renaissance knot gardens were composed of square compartments. A small garden might consist of one compartment, while large gardens might contain six or eight compartments.