Trichomes and cold climate

I brought five plants to flower at the same time. Four turned herm and were moved outside in Southern California, the other was left in the warm grow room. The indoor plant is a different strain that the outdoor four. The indoor plant is rich with trichomes. The outdoor plants are very sparse. Will cold weather (never cooler than 50°F) inhibit trichomes? Or is this a difference in the strain or a fault of hermaphrodites?