Answer: Sago palm is not really a palm, but a cycad. It is a tropical plant, preferring warm and humid conditions. It is rated for cold hardiness in USDA zones 9-11. USDA zone 9 has average annual minimum temperatures of 20 to 30 degrees F. I'm not sure where you are in RI, but that state is in USDA zones 5 or 6. USDA zone 6 has average annual minimum temperatures of minus 10 to 0 degrees F. USDA zone 5 has average annual minimum temperatures of minus 20 to minus 10 degrees F. Even with a makeshift greenhouse, I wouldn't recommend leaving them outdoors. Perhaps there's a friend or neighbor with enough space? If you must leave them outdoors, don't use plastic. Purchase a frost cloth/blanket rated for your temperature zone. The A-frame is a good idea, as you don't want anything touching the foliage. It wasn't clear from your question, but I'm assuming they are in pots. If you can put them in a spot out of wind, where there is reflected sun against a wall and/or heat from the house that forms a little microclimate that is a bit warmer than otherwise, that would help. You might also want to get a minimum/maximum thermometer and track the average outdoor temperatures at your house and keep a record of it. It will help you determine what plants will be best suited. Good luck!
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