Indoor Growing (v2): Insulated Garage Cabinet

A couple of weeks ago I finished (except for doors) building my indoor growing cabinet in our garage.  Last year I built a smaller version that was basically comprised of a shelf, full spectrum fluorescent lights, a heat mat, plastic sheeting, and a tray.  v2 is about the same width (48”) but taller and deeper (36” x 20”).  I lined it with insulating foam board and plastic sheeting.  I tried to overlap the sheeting so that lower layers extend above the bottom of sheets above.  I thought this would help moisture rise and leave the space as opposed to get caught in the walls of the cabinet. 

ASIDE: part of the delay in posting this was that I wanted to use a Python Tumblr module to automagically load the pics I wanted to share but haven’t had a chance to dig into it yet so I’m including a subset of pics which is probably ideal anyway.  I did finally figure out how to post high-res pics though I’m still looking for an “easy way.”

I built the cabinet/box out of some OSB (think wood chips glued together into a plywood like sheet) and some scrap 2x4’s I had lying around.  I used a nail gun and skilsaw (circular saw) to tie the parts together but nails/hammer or screws/automatic screwdriver will work—just more slowly.  I didn’t work from drawings but “made it work,” not worrying too much about having all the dimensions perfectly optimized.  I did make sure that two cans (the fixtures for the lighting) would fit within the confines of the box and that the top would be a good height to act as a counter/work surface.

I had just pulled some low voltage wire out of the crawl space so I re-purposed it to act as lines from which I could hang the lights.  The bottom of the box is lined with plastic like the sides but between it at the heat mat I placed cardboard and some plywood for insulation and to ensure the mat isn’t directly on top of more combustible plastic.

I placed starts I purchased at the Seattle Tilth edible plant sale in a flat bin I had lying around.  I set up a water jug with a spigot and attached some plastic tubing to the nozzle so that I can easily siphon water into the bin and onto each pot’s contents when needed (very handy… will have to post pics of this later).

Peppers, basil, eggplant, and tomatoes are prominent in this photo (front to back).  After taking this photo I’ve subsequently put the tall plants in back and the short ones in front and have one set of lights raised higher than the other set.  I’ve also had to spritz off aphids.  Haven’t seen them be a big issue in the past but the numbers I’m seeing make me think that I’d have a problem if I wasn’t blasting them with water from a spray bottle.

Eventually I want to put doors on the “cabinet.” At this point in the project it was getting late and I needed to get things up and running so I cut a heavy duty black plastic bag into two pieces and stapled it to the wood frame to act as a heat curtain.  It turned out to be the perfect solution because without a thermostat the heat from the lights and heat mat actually get hotter than I want so this serves as a crude thermostat (by not keeping the heat in too efficiently).  I’ve started to play with two timers to turn the mat on and off at varying intervals to keep the temp right.  I definitely should get a thermostat but that’s more $s and only really justified if I have doors (which is more work and will mean that I have to find a good way to run the wiring into the box and not just under the curtains).  I did purchase a GFCI extension cord and placed a smoke detector above the box to ensure that if something electrical goes wrong it will be shutdown and detected before there’s a problem.  I sure hope so anyway!

Here’s some of the tools I used to attach the plastic sheeting, insulate, and install the lights.

I’ve heard in the news recently that indoor pot growing (which I’m not doing) actually has a huge energy footprint.  As far as I understand, that scale/flavor of operation is using lights that are way more powerful than the fluorescents that I’m using.  That said, I’d like to figure out how much energy I’m using.  I don’t want to carelessly let free/clean solar energy go to waste outside because it’s convenient for me to grow indoors.  Next year I’ll get a little green house going and hopefully cut down on my energy footprint.  Speaking of footprint, I’ve been reading about drip irrigation which will be great for making irrigating easier and for conserving water. Combining the indoor growing with a good outdoor cold frame/green house is definitely where I hope to be next spring.

Peace out.

—Matt