This episode of Plain Gardening takes place on Bill Finch’s porch…or as he calls it, his “cold weather greenhouse”. The plants, including ferns, citrus, and nasturtium, look great despite several recent frigid cold snaps.
With more cold weather on the way, potted plants are in the most danger because air circulates around the roots. Bill has some suggestions that may help your plants survive and thrive using heat from the earth. You may recall an earlier episode where we showed a ground temperature of over 60 degrees even with air temperatures in the 30s!
Let’s start with hanging plants. With nothing to connect them to the warm ground, their roots get cold very quickly, and that can kill them. Don’t just put a sheet over hanging plants; either take them inside or set them on the ground before covering with a sheet.
Bill took lots of plants indoors when temperatures dropped into the teens and low 20s, including a very large blood orange. He says it was worth the effort…but that’s probably the last time he’ll lug such a heavy pot indoors. So what do you do with large potted plants?
First, if you have a south-facing porch, move the plants there. Sheltered from the wind and with a roof above to hold in heat, some porches can act like a greenhouse. Even moreso if the porch sides are covered with plastic. North-facing porches don’t work as well because the cold winds blow directly onto them.
Another method is to tip the pot over onto the ground in your yard. That puts leaves and branches as close as possible to the ground. Cover with a cloth sheet and then a tarp. The sheet keeps the cold plastic from contacting the plant. The tarp contains heat from the ground, keeping plants alive to very low temperatures. Don’t forget to cover the pot—that’s where the roots are!