Since I knew next-to-nothing about medieval gardening, I started with a broad overview of the early medieval period and the British Isles. There seem to be several good books on the subject, and I'm working my way through them. (I'll post more on those sources later.)
These sources have a heavy focus on monastic gardens, since those are some of the most well documented and preserved. There is also some discussion of lay gardens, most of which are utilitarian kitchen gardens and/or small crop fields.
My initial impression is that there are some different types of gardens I can create and look more into:
1. Orchard - an open stand of fruit trees
2. Herber - a small, enclosed garden with mixed elements for utility, beauty, shade, and recreation
3. Kitchen Garden - a utility garden planted with herbs and possibly fruits and vegetables for the kitchen
4. Physic Garden - a small garden with medicinal plants and sometimes space for patients to take walks
5. Vegetable Field - a garden or field of varying size where vegetables are planted and cultivated in traditional row or mound formation
6. Vineyard - a grape garden, either with vines cultivated onto supports or trailing along the ground
7. Leisure Garden - a garden where the focus is beauty and tranquility rather than utility, usually with flowers, sweet-smelling shade trees, open lawns with or without flowers, and seating areas for enjoying it in relative comfort
8. Pleasure Park - a managed and enclosed forest where game animals could be hunted for sport
These are all attractive options, but I think I'll probably get started on the orchard, herber, and vineyard first. The herber will let me play around with elements from most of the others to get started!