Our garage is attached, and under the house built into the slope we live on.
The garage doors open on grade...and then the basement is behind the garage built into the slope.
You have to walk through a door in the garage into the basement. Then there is a staircase from the basement into the main house.
And when you stack the lotus and potted water lilies, they insulated each other, up against the back wall...they are very protected.
You just gotta keep the garage door closed at all times.
We keep a thermometer in the garage, never seen it go below 35* unless the door is open for too long. (usually DHs fault
)
Once you close the garage doors, the heat from the Jeep or Trucks engine brings it back up over freezing.