March 14, 2010

diy grow light

Time to start seedlings! Inspired by our friends Tom and Susan, we made this grow light. Store-bought grow lights can cost a pretty penny, but you can use standard linear fluorescents. You don't even need special full-spectrum lamps. Wikipedia and another source say that cool blue color temperature lamps are better for the initial growth stage, whereas the warm red-orange spectrum lamps are better for the flowering stage. Full-spectrum lamps can be ten times as expensive as standard lamps and are less efficient at providing the blue spectrum necessary for the initial growth stage. You can use one cooler color lamp and one warmer color lamp if you want to keep growing into the flowering stage. If you are a plant biologist, please correct me if I am wrong.

I think much of what you pay for in a commercial grow light is the super-duper reflector. We just used a section of round aluminum ductwork and it seems to work very well.

If you own your abode or if you have a cool landlord, you can simply hang the fluorescent fixture from the ceiling above your seedling table. Since we don't own and our landlord isn't that cool, we built a stand out of PVC pipe to hold up the fluorescent bulbs. From what we've read, you're supposed to keep fluorescent lights 4 inches above the tops of the plants, so we incorporated a method to raise and lower the lights by adjusting the length of chain.

Our total cost was about $35 but I am sure if you found a used 4 foot fixture you could do it for way less. For maximum energy efficiency, look for T8 or T5 lamps, and avoid T12s. We spent most of the $35 on a new, energy efficient 2 foot T5 fixture because we live in a tiny apartment where counter space is limited.

Here's what we used:
4 - 5" long 3/4" diameter PVC pipe (stand base)
2 - 28" long 3/4" diameter PVC pipe (stand base)
2 - 20" long 3/4" diameter PVC pipe (stand verticals)
1 - 28" long 3/4" diameter PVC pipe (stand top)
8 - 3/4" PVC tee connector (stand joints)
2 - 1 1/4" diameter rings (hang around the top of the stand)
2 - carabiners (connect the light fixture to the rings)
1 - 2-lamp T5 linear fluorescent light fixture
1 - grounded power cord
1 - switch
1 - 3x24" aluminum snap lock duct vent (light reflector)

Optional bits:
2 - 6" chains (to adjust the height of the light fixture)
2 - carabiners (to adjust the height of the light fixture)
1 - lighting timer (to turn the light on and off when you're not around)


  1. i stopped by to look at recipes, and was so happy to find this awesome grow-light! we are starting our seedlings soon, and this will be so much help! thanks!

  2. cool! if you end up designing yours differently, you should totally post a picture in the comments here. it would be fun to see different people's projects.