As above, all witches somehow practice solitary. Many who do this, are also in covens.
The thing is, a witch is a personal journey. While a group, can offer you help, love,ect. Learning is not spoonfed to people, therefore being a witch is based on knowledge and connection with yourself, and nature.
To me, hedge witchery is kinda like kitchen witchery? A solitary witch is still seen as the above. You can be doing kitchen magic, alone. Therefore you're solitary. Get it?