what can I plant under and around my new hawthorn tree? I can't picture anything in my mind!
If your tree has just been planted then it is advisable not to plant anything around its base until it becomes fully established.
You'll be able to put early spring bulbs in there, although you'd need to keep them quite far from the trunk as it will eventually get to a decent sized tree.
Depending on the size, the amount of shade created, and the amount of moisture in the soil, you might be able to put some other perennials there like hardy geraniums.
You are most welcome.