Heating row tunnels and grow box with Christmas lights


Currently it is 16 degrees outside and given my grow box containing jalapeno peppers is in my unheated detached garage, which can bring some challenges.  Like most plants, peppers will continue to grow in the range of 60 to 90 degrees, but thrive in 70 to 90 degrees.  With the lights on the grow box gets to about 60 degrees but drips to the 50’s at night.  This will result in plants having stunted growth and begin dropping blossoms before they can start bearing fruit.

My solution, a string of green mini Christmas lights.  Just to clarify these are your typical small bulb Christmas lights not LEDs, given the efficiency of LEDs they do not product much extra heat which is what I am going for here. I also chose green Christmas lights because plants do not absorb this wavelength very well so they can be left on at night to keep heating while still letting the plants “sleep”. 

Of course results will vary depending on the size of your grow box or outside row tunnel, insulation, and exterior temperature, but I am seeing 8-10 degree increase in temperature with a single string (50 bulbs)

I am always open to new ideas to safely, cheaply and efficiently heat my grow box or row tunnel so if anyone has any other suggestions please add a comment.

11 Responses to “Heating row tunnels and grow box with Christmas lights”

  1. The Eclectic Engineer Says:

    it's seems like your getting awfully complicated. Wouldn't it be simpler, more efficient and cheaper to put in a heating pad/reptile aquarium heater in the enclosure and use a relay to turn it on/off?

  2. The Cheap Vegetable Gardener Says:

    Actually I tried the heating pad though it helps with the surface temperature though the abient still stays very cold. I'll have to take a look at the pet store, only retile heaters I have seen is a heat lamp though it was thermostat controlled so could be too intense and also add light during what the plants thinks should be night time. I will have to see if they have any non-light options out there so I could get one relay back for watering or an air pump

  3. The Eclectic Engineer Says:

  4. Red Icculus Says:

    Great idea with the green LED's. Jalapenos will grow just fine in cold weather down to freezing, they just won't be as spicy when they are ripe.

  5. The Cheap Vegetable Gardener Says:

    Engineer, Thanks for the links never seen the ceramic heater variety would be pretty easy addition for a grow box though wouldn't trust the high voltage in a row tunnel though.Red, well technically not LEDs those are too efficient and don't put out enough heat. I am new to the growing peppers during the winter, though from what I have read peppers will drop their blossoms if they get out of the 50-90 degree range. Though I agree after they have some fruit growing they are pretty hardy.

  6. Anonymous Says:

  7. Diego Says:

    Great stuff. http://www.cheapvegetablegardener.com is amazing.

  8. SilverGhost Says:

    Hey, pretty impressive website and ideas, being a developper myself I had the idea of creating something like this for my daughter ;).

    Why don’t you just use a heating resistor salvaged from a toaster or grill controlled by a TRIAC, and blow a fan into it.

    I know it is FAR too much heat, but you may be able to use it in very small step ?

  9. The Cheap Vegetable Gardener Says:

    SilverGhost, fire hazard would be my first concern I have seen someone use a hair dryer as well which I thought was good idea though got to ensure everything is waterproof 🙂

  10. robbert Says:

    easy get a propagater tern it upside down works like a heat mat put grow tub on top keeps plants lovly and warm are better still this what i will be doing get a plant box that you see in garden centers put load a led chrismass lights in on the inside of the planter get a heated long window sill propagater tern planter upside down put on propagater of you go heating for the plants and light

  11. LED/Christmas light projects - The Cheap Vegetable Gardener Says:

    […] Heating row tunnels and grow box with Christmas lights […]

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