As this is the first year for the hoop house, we've been tracking temps and comparing the plants indoors vs the ones outside. Here's an update:
Temps have varied greatly, with highs inside the hoop house hitting 86 on sunny days (only briefly, or I'd spend all my time there), and lows averaging 2 to 4 degrees warmer than the outdoor lows.
Soil temperature is generally 8 to 10 degrees warmer inside than out.
As for the plants, all of the pics below were taken on the same day for comparison, just last week (Feb. 3).
Grand Rapids Lettuce outside
Grand Rapids Lettuce inside
Toscano Kale indoors.
Toscano Kale outdoors. Obviously not a fan of the cold.
Collards inside hoop house.
Red Cabbage inside hoop house.
Red Cabbage outside.
Red Russian Kale inside hoop house.
As you can see by this last photo, not all kale is created equal. This variety is more cold hardy than the Toscano kale.
Varieties do make a difference. Some are bred for cold tolerance, while others are bred for heat tolerance, or disease resistance, or all of the above. Do your research before choosing your hoop house plants.
Happy Gardening! And don't miss tomorrow's seed starting workshop!!