ideas how to turn front porch into greenhouse

I have a 6 ' x 22 ' open porch I want to enclose for both a greenhouse and passive solar heat. I am also considering a rainwater catch system below the porch which may be used a thermal mass. Also considering solar panels for fans and water pumps . Any suggestions on what to use for a rainwater catch systen and design ideas for the greenhouse would be great. I am also planning on installing radient floor heat from a woodburning water based furnace which will also be heating my house.