That sounds like a great idea for geothermal hotspots. You might even consider going a step further, using geothermal to accelerate growth through enhanced temperatures and humidity control as well. If you plan to keep the resulting plant matter for a long time (e.g. as lumber for houses/cabins) your greenhouse might also help with carbon capture.
There's a movie (available on Youtube: "How Geothermal Energy Revolutionized Iceland's Greenhouses") that seems to validate your recommendation (especially starting ~4:50):
