By the next day (Fri the 18th) the plants were over 10cm tall, I think closer to 12. In the meantime I'd been frying my brain by reading about how much light was needed and was getting worried I had an inadequate supply. Since it was a payday of sorts I had a little bit of cash, and went out to improve the lighting setup.

I bought 2 light sockets, 2 light socket Y-splitters, and a short length of 14/2 house wire, and a small package of 333 size marrettes from Home Depot - about $15 in total with tax. (I also found some 5000K 27W CFL bulbs - a pack of 4 for about $17.50 + tax - but when I got home I found they were broken inside the package so did not end up using them.) At the dollar store, I bought 2 of those "Emergency blankets" made of thin, shiny Mylar-like plastic, some cup hooks, a short extension cord, and a dog leash made of chain (obviously, $5 plus tax). At Wal-Mart I bought another small 6" clip-on fan to replace the one I had stuck in the greenhouse.

The next day, we took everything out of the greenhouse. While the wife lined the interior walls with pieces of the emergency blankets, I used a piece of plywood the size of the 2 sockets, used a hole saw to cut out spaces in the wood for the wires to pass through, wired and mounted the sockets, and stapled down the wires on the back of the piece of plywood leaving some working length. I then cut off the female end of the extension cord and stripped the wires, marked it so I would know which one was the line and which was the neutral, and connected the end of the newly created power cord to the appropriate wires from the light sockets with the marrettes. I then put 2 cup hooks in the back of the piece of plywood, removed the handle from the dog leash, and strung the chain from the hooks over the top bar of the greenhouse and back onto the other hook, and then screwed in the Y-sockets. Since the bulbs were broken this meant a return trip to HD, but those bulbs ended up just being returned when I found 2-packs of 26W 6500K CFLs at another store for $7.50 or so - 2x$7.50+tax= about $17 total. Into the 4 available sockets they went.

I have some timers around which I had received from Freecycle, so I connected the lights to the timer, set it to be on 23 hours and off for 1. Closed things up, and off to bed.