I'm playing an intellectual game with myself, where I'm creating magi along certain themes. The current challenge is to create an Herbam specialist, but the question is how to go with that. Affinity with Herbam seems almost a given. I don't think Puissant is the way to go, but perhaps Magic Focus of some sort.
The idea is that I want a magus who can grow plants that are larger and healthier than normal, who can grow them inside as well. I'm seeing this magus as someone who is at home in the natural world, working in harmony with the plants. I'm thinking Faerie Blood with a dryad somewhere in her family line.
The other question then becomes, which House? I don't think Bjornear, but Merinita seems a strong possibility.