My peppers have recovered beautifully from the last 20 degree freeze in their new micro-greenhouse. Now I am preparing to keep them alive as winter progresses with likely much deeper freezes.
I kept my peppers alive a couple of weeks ago during the 20 freezes by using a heat lamp. But it is my preference to find off-grid solutions that are also inexpensive. I have used kerosene lamps before for this purpose but they tend to deposit soot on the plastic which is a problem to clean off, and kerosene is expensive. This year I am going to try these home made flower pot heaters. They should provide comparable heat to a kerosene lamp (at least the larger size I am making) but should be less expensive to operate and the soot should remain inside the pot.
There are several problems with the standard directions for these pots. One is the tea light candles most frequently recommended for this. Their burn time is just not long enough to get through the night. I don’t know about you, but I really don’t want to go out on a cold, cold night to switch them out with new ones. So I wanted to be able to use much larger, longer burning candles that also don’t cost a fortune. My solution is to use home-made, multi-wick candles using shortening or lard or other rendered fat from the homestead as a fuel (will make another post specifically on that). But to use this, I needed a deeper base that can hold them safely under the pots.
This leads into problem number 2 most commonly associated with this. Some use bread pans which are deeper but unstable. Another person screwed on the base which looked really nice, but would require more time and effort to screw off to put in new candles, especially if you are using something larger than the standard tea lights recommended for this. And his base was way too shallow for anything bigger than tea lights. I solved this problem by finding a clay square shaped pot that the larger pot (10″ can comfortably rest on) and the smaller 8″ pot can snugly fit inside, making a very stable and secure fit. The corners provide opening for oxygen to feed the candles so that I do not have to worry about any spacers. And the base is heavy enough to not be tippy when the heavy pots are fitted on top.
I used a 6″ carriage bolt to hold the two pots together. It also allowed me to create a nice little handle so that I can easily lift the pots from the base.
Materials I used for creating my pot heaters
1 10″ clay pot
1 8″ clay pot
1 9″x4″ square clay pot for base
1 6″x1/2″ carriage bolt
(could be wider, the holes in these pots are closer to 3/4″ but this is what I had)
At least 2 2″x1/2″ washers (larger holes if you use wider bolts)
8 1″ (or 2″) x 1/2″ washers (again, should be sized to fit the bolt used)
9 1/2″ nuts (or sized to fit bolt used)
I first screw on a nut to the carriage bolt, but not all the way to leave enough to easily grab. I then slide on a 2 inch washer and then 10″ pot.
Inside the pot I slid in a 2″ washer and then screw in tightly another nut.
I then slide in another washer before sliding on the 8″ pot.
I then alternate washers and nuts to fill the remaining length of bolt. It is my understanding that the purpose of this is to provide more thermal mass and store more heat. Not all pot heater directions, however, include this and a shorter bolt and fewer nuts and washers could be used.
I do not have grandiose expectations with this heater. It certainly is not a high btu device. But it is my hope that it is comparable to a kerosene lamp and will be enough to keep my peppers from freezing in their very small greenhouse. If we are expecting very low teens or single digit lows, I will probably put blankets over the greenhouses. But after my experience with the last freeze, I know a heat source is necessary. The black water barrels should help. But it is my hope that this simple and inexpensive device should provide an extra edge. We will see…