More about seedlings and grow lights

Bob wrote a post earlier this week about LED grow lights and duration.

If you can’t afford LED grow lights, or you have some old shop light fixtures, you can make do with those inexpensive hanging shop fluorescent fixtures that use 2 tubes each. I converted the front hall closet into a grow op with two 4 ft units hung cup hooks screwed into the bottom of pine shelves. The only thing I would change is I would buy the fixture with the flared reflector so the seedlings at the edges of the trays were more evenly lit across the width of the tray (they tend to lean in a bit). I lined my closet with aluminum foil and drape some foil over the front of the trays to compensate.

If you buy a fluorescent tube set up, you need to know a little about colour temperature. Not much, though. ‘Kelvin’ is the scale used for colour temperature. If you’ve ever dabbled in photography, you’ll have a sense of what this means, because colour temperature has traditionally been used to describe the light sources, and setting ‘white balances’ and such. I read somewhere that was probably because the folks who invented photography were also physicists. It’s not really about light sources or levels, but you can go nerd out on this 3 minute video if you need to know more (yes, I watched it, of course I did).

Color temperatures over 5000 K are called “cool colors” (bluish), while lower color temperatures (2700–3000 K) are called “warm colors” (yellowish).

Anywho, when you purchase the fluorescent tubes, you want to make sure that the colour matches what you want to grow. Lightbulbs that are between 3,000 to 4,500K are better for growing leaves, while lower colour temperatures, around 2,700 K are good for flowering and fruiting stages.

I have 3,000K bulbs in my set up.