Here is a shot of the boxes that protect my two biggest trachys. The box on the left is 8 feet tall and the box on the right is 6 feet tall. The interior dimensions are 40 inches by 40 inches. As you can see, I have removed the south side foam panel to let in light. I do this every day and it also gives me free heat. It goes back on at night. Each is heated with a 750 watt space heater set at 40F.
The trachy on the right has been with me since 2008 and started as a 3 gallon. I planted the one on the left this past June and was a 15 gallon.
Here is a closeup of the protection. Double poly (one layer on inside, one layer on outside, 1 1/2-inch gap in between. Then 1 1/2-inch foam on the outside screwed on with lag bolts and washers. The lid is a 2-by-2 frame with plywood top and 1 1/2-inch foam insulation underneath.
Here is a shot of the protection for the four trachys I planted this spring. These boxes are 30 inches by 30 inches inside and are doubly poly. These are each heated with a single strand of 100 mini Christmas lights that runs on a thermocube, 35F on/45F off. The 5-gallon bucket is filled with leaves and has a tiny trachy in that is just starting its character leaves. The other side of the property has one of these too. No heat is in these buckets, just a test to see what happens.
And finally, here is a wide-angle shot of my yard.
Some stats for you, current temperature is 28F outside at 1:30 pm.
Inside the 8-foot trachy enclosure the temp is: 64.0F
Inside the 6-foot trachy enclosure the temp is: 56.7F
Inside the little trachy boxes the temp is: 66.7F
They have reached their peak temps with full sun, so all looks good I think.
Last night it fell to 15.2F.
Temp temps in both the insulated boxes were 40F as expected because of the space heaters. The temps in the uninsulated poly boxes fell to 34.0F. So I think the mini lights will be a "win".
