Keep in mind, roots will freeze in winter when exposed in containers without a protective insulated sleeve. It's the above ground growth that's most hardy. You can build large pressure treated wooden containers and unsulate them with polyurethane sheeting on all 4 sides and the bottom. Cheers, LPN.
Hi LPN- just want to clarify. Polyurethane sheeting is to be wrapped outside the box on the 4 corners and bottom correct? Palma
I would apply the insulation to the sides, and if practical throw some mulch over the top of the soil in the pot. Insulating the bottom works against our purpose, as the only source of heat for the media is from the ground.
I stand corrected ... polystyrene is the correct term and not "Polyurethane" as in my above post. Foam board is another term and can be purchased in varing thickness. I've lined the INSIDE of the square containers on all 4 sides and the bottom. It stays in place providing protection from winter freezing and summer heat.
