How to heat citrus in winter

Thanks for the thermostat link, I got a programable one for about 15$. Looks awesome. I’m going to go passive solar and water for the citrus inground, but this thermostat looks good for other projects like my seedlings.

Just an update: my plan worked really well. Of all my citrus, the Eureka lemon is in the best shape now despite being the most sensitive. It’s was next to the water tank with old windows for a shield. I left the top open and frost cloth. The tip was exposed a few inches and looks like someone took a blowtorch to it.

Trying to generate heat from a battery ,solar set up is a bad idea. Sorry.
I think you will end up with a dead battery and a frozen tree.
Your wallet will be a little lighter as well

I agree with you, I’m gonna focus on passive methods. The black water tank I used was pretty good, but the shape limits it s bit, and at $100 a pop, it would be a bit wasteful to do an orchard, one for each tree or two.
I have an old bathtub for collecting water at the garden, and all the weeds around it benefit from the heat it throws off in the winter.
I’m impressed with the durability of large clear plastic pop and alcohol bottles. They are free. It might make an interesting recycle project to epoxy a huge block of them together, or perhaps make a windshield wall. They are clear, so they should heat up quite a bit on sunny days.