Baby its cold outside, but its nice and snug inside your Grow Y’own raised bed when the covers are on! Here are a few of the ways which people are keeping their crops warm during the coldest parts of the Winter!
1) By using the Summer cover, with the Winter cover on top of it, a ‘double-paned’ window effect has been created. The Summer cover serves as an insulation layer, while the Winter cover keeps the snow, hail, freezing rain, frost, and wind on the outside of the unit. Each layer you put on lowers the ‘Zone’ rating 1-1/2 times. Some people even put a layer of the Summer Insulate cloth draped over their plants inside.
2) Several clients have spray painted 1 gallon plastic milk jugs, black, filled them with water, and put them in the sun during the day to heat up. At night, they put 2-4 inside each 4’x8′ unit. During the night, the jugs radiate extra warmth.
3) Many people have used the light bulb inside the upside down flower pot method. I get a ‘work light’, that has an aluminum cage on it. I remove the cage, clamp, and other pieces, so that all you have left is the socket handle attached to the cord. You’ll have to drill a 1-1/4″ hole to get the plug through to the outside from inside the bed. I then fill the space around the cord in the hole I’ve drilled with a small piece of metal lath, wire, steel wool, or insulation. Using a 75 watt light bulb on the cord, simply set it upright inside a 10″ upside-down clay flower pot, with the small drainage hole of the pot on top. I put a small, flat rock over the hole so that water doesn’t get in and blow out the bulb. The flower pot heats up almost to the point that you can’t put your hand on it, and radiates the heat through the night. In the morning, you can either unplug the extension cord, or leave it on until the ambient temperature outside reaches about 45 degrees. If it stays super cold outside, simply leave it on.
We also use an ‘Easy Heat EH 38 plug’ to automatically control the heat. It has a sensor built in that kicks the power on to the cord when the temp outside hits 38 degrees. In the morning when it gets to 45 degrees, it kicks off. You plug the EH 38 into an outside receptacle, and the cord into it. The plug costs about $20, and they are available at your local hardware store, or electrical or plumbing store outlets. This is the most popular way to automatically control the temp inside your units.
4) Lining the outside of your bed(s) with straw bales keeps the soil temperature warmer, which also translates into a warmer ambient environment inside.
5) Locating your grow bed against a south-facing masonry or stucco wall helps tremendously. During the day, the wall absorbs the Winter sun heat, and then radiates it during the night back towards the unit. And it doesn’t cost a thing! This coupled with the black water jugs, has given people the ability to heat and grow profusely with- out any additional, supplemental costs.
I hope these tips help, as the main reason is to be able to grow year round, rather than just one Spring to Fall season.
I’d love to hear about other methods that you’ve tried, that work, and can be passed on to all our ‘farmers-in -arms’!