Many green house owners, both commercial and private have discovered that root zone heating is both a very efficient way to heat plants and that it develops a much healthier plant.
   In designing a root zone heating system you need at least 30 Btu. inside and at least 50 Btu. per square foot outside. 12 inch centers work in most cases.
    You can place the tubing in the soil, in concrete or staple it under the benches, remember that the pex tubing must be protected from direct sun light.
     Many green house operators vent the exhaust from gas heaters inside the green house to stimulate plant growth.
     A common mistake for first timers installing a small system is under sizing the heater, standard water heaters and instantaneous heaters are a very poor choice, and seldom are satisfactory.