Seed Starting Greenhouse

Seed starting has not been going very well this year. Wife started several a few weeks back, but they got leggy and tall very quickly with almost no root development. They weren't getting enough light, which is unsurprising - our only southern-exposed window is in the middle of our back door. We did our best, but ultimately starting anything but the lowest-light seeds in our house ain't gonna happen.

Enter a sale on greenhouses last weekend.

We picked up a plastic greenhouse for seed starting. It's about 5' by 5', and tall enough I can stand in it.

Our new seed-starting greenhouse, with the passive water temperature control being filled up.
That door in the back is the ONLY southern-facing window in the house.  :/

We had originally set it up on the deck, and put our kitchen herbs, aloe plant, and started tomatoes in it. Within a few short hours, our tomatoes were crispy, the aloe was cooked, and the herbs were simply destroyed. We had no idea how HOT it would get in there.

So, we started to leave the door open during the day and shut at night, but the temperature fluctuations were still pretty wild. Wife discovered online that we could use a "thermal mass" to help regulate heat. We decided on a 55-gallon drum of water (partially because it's a lot of mass at 400+ pounds, and partially because we had an extra drum out back). So, I moved the greenhouse off the deck, with Wife's and Thing #1's help. We set it down below the deck, where it is in full sun all day long. After moving it, I added the drum and filled it up.

After moving the seed trays in, the temperature was regulated very well during the day. It did NOT get too hot. It was warmer than the outside temperatures, but not hot.

Seed trays germinating in the greenhouse. 55-gallon passive heat drum to the left.

So, hopefully, this works out and keeps the temps stable and the light plentiful.