Since the founding of Westminster Abbey medicinal herbs have been grown on the site that is now College Garden. Records kept in the Abbey Library mention the construction of a herbarium, which was completed in 1306. There is a further reference for that year to a 'little garden' with a locked gate, which may be this same small herb garden. Quite why it was kept locked is unclear.

Detailed research undertaken by the garden historian Dr. John Harvey, published in 1992, suggests that the herbarium of 1306 was located near the site of the Infirmary, in an area immediately to the right of the present entrance to the garden. This area is now occupied by a knot garden, its spaces filled with white and blue lavender. In the three borders to the sides a selection of medicinal herbs have been planted, with another dozen or so arranged among them in pots.