ACRYLIC vs. Gel-Coat Fiberglass. Acrylic. One piece construction with dome. This adds strength to the unit and eliminates post installation. damage, no seams to caulk and gather mold and mildew, dome eliminates ceiling maintenance. Non porous surface, Easy to clean, no pores to catch soap, dirt, body oils.
In cold frame gardening, a cold frame is a simple structure that usually works like a mini-greenhouse. It has a wooden frame with a transparent roof made from glass and is always constructed low to the ground to provide proper insulation.
The oldest, and most commonly used, is the USDA Zone Hardiness map which calculates 11 zones and tells what level of winter cold a plant could experience in a location. Seattle falls into zone 8b with expected winter minimums of 15 to 20.