Bottom Heated Greenhouse Tables *Electric*

Heated Greenhouse Benches can be a great tool for consistently happy seed germinating and transplant growth. My benches are not just for starting seeds but for maintaining suitable growing conditions without the use of an additional propane heater for the air.
Root Zone heating systems are often hydronic- which means that propane or electric is used to heat water and then that hot water transfers its heat into the table and trays on the water pipes. This electric system is a variation on that theme and required a bit of a build-out.
🥬The heated tables shown here are 80 square foot (two 40 squarefoot tables).
🥬The two tables provide 3280 BTU/hr at 1000 watts
🥬This means that the operating cost is about $3.00 per 24 hours (the heater is rarely on for a whole day since the sun warms it during the daytime I estimate its more like 1.00 per day during the cold months)
They definitely work best when the trays cover the entire surface and the rowcover helps slow down the heat loss (without it, the air temp can damage the plants and the heating tables have a hard time keeping up!)
To heat a greenhouse that is this small (10x 16) using a propane heater to heat the air would require at least 10,000 BTUS, a propane tank and cost about $450 in propane per year ( I estimate that it costs about $144 per year to heat these tables), and a heater to be installed into the small space and vented to the outside. They normally don't make propane heaters this small that are also vented (essential in a GH), so that is what led me to explore this option and see if it provided all the heat that the plants required.
Additional resources on the benefits of 'root zone heating systems' and other popular designs:
ceac.arizona.e...
for calculating the BTU requirement for heating yoru greenhouse AIR: www.littlegreen...
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ABOUT: Kat Johnson began learning about organic farming in 2005, as a high school intern on an organic farm in California. Since then, she has worked on ten organic vegetable, urban, and livestock farms in four states and gotten her hands dirty in all aspects of farming operations from hauling water, to management, sales. In 2021 she began designing her own ‘Farmlet’ In Floyd County and went full time as Kat The Farmer growing salad-centric crops along with creating value added products. Kat believes in transparency in growing practices, and in creating a community of growers that can share information so that we all succeed in creating more resilient farms, food systems, and the communities they support.

[@cpnotill9264]

Well done Kat! Very nice set up.....❤🌱

[@katthefarmer]

Thanks so much! 😊

[@davidmalinowski7930]

Great video!

[@katthefarmer]

Glad you enjoyed it

[@Rymorin4]

Thank you so much most helpful video of it's kind so far. I am going to build one with the same tools, but I would like to use pea gravel or sand instead of concrete. Did you install the electrical cable on your own or did you get help from an electrician? Was it easy to install?