Herbs such as rosemary were commonly grown in medieval England and used extensively in medieval recipes as well as for medicinal purposes.
Herbs and flowers were used extensively in medieval times. In fact they had a dual purpose being used for both cooking and for medicinal purposes.
Most households, rich or poor, grew their own medieval herbs and flowers because health was a serious issue and adding extra flavour to food was important given how bland the pottage, meat and vegetables could taste in their own right.
The definitive idea of a herb garden still prevails today. There are many medieval castles with wonderful gardens, an intrinsic part of which is a dedicated herb garden. We owe much to our medieval ancestors for passing down the tradition of growing our own herbs and flowers.