Insulating and Winterizing the Greenhouse

The temperatures are dropping, and it's time to get my new greenhouse ready for winter!  I'd be thrilled to keep my greenhouse above 55°F (13°C) for the plants that I want to keep in there, but I'd be fine with above 45°F (7°C) with our winter temperatures. We're using a space heater right now to heat the greenhouse, but in order to keep energy costs down, we want to insulate it the best we can.

After researching insulation techniques, here are the things that we did:

1. Insulate the inside with bubble wrap.

We're still working on bubble wrapping the entire thing - it takes awhile!  We used the kind with larger bubbles.

2. Place styrofoam insulation around lower half of the interior walls.

We have wooden walls on the bottom of our greenhouse.  We bought some styrofoam insulation, as well as supplemented with all the random pieces of styrofoam (and boxes of styrofoam bits) that we have been saving.

3.  Fill up large containers with water.

The water helps stabilize the temperatures.  During the day they will warm up, and at night they will release heat.  The more containers, the better!

4.  Stop air from leaking through.

We put foam weatherstripping around the door, since that is where a lot of heat escapes.  I also plan to make a weatherproof cushion to place at the base of the door outside, to further insulate the gap at the bottom of the door.  On the inside, we have a blanket pushed up against the door.

We realized that we had a lot of heat escaping from the foundation of the greenhouse, where the greenhouse meets the base that it sits on.  Since we had already put the styrofoam on the interior, we decided not to spray foam insulation into the cracks (and such ventilation is good in summer anyway.)  Instead we put salt marsh hay (this area's equivalent to pine straw) around the exterior.  It immediately made a difference and helped tremendously in keeping the greenhouse warm.

I do realize we've probably just invited all the mice in the area to come stay in our nice hay filled bed.  Mr. Red House says they'll add body heat and be of help.  I have my doubts about that and just hope that they don't do too much damage to my flower bed.  (My next order of business is looking into rodent repellants!)

The other option I've seen is to dig a trench next to the greenhouse and half bury sheets of styrofoam right next to the exterior for insulation.  After just building a wall around my shade garden, we were not keen on doing more digging, and a trench would disrupt my flower beds, so we decided against it.

I have to give a shout out to Mr. Red House for all his help with the sensors in the greenhouse.  As soon as I talked about wanting a greenhouse, he's been excited to integrate as much technology as he could in there.  One day, thanks to my technology-loving husband, I'm sure I will end up locked in my own house by an evil computer, but other than that I have to admit that technology is very useful. (Don't let Mr. Red House know I think that.)

The sensors Mr. Red House has put in the greenhouse have been immensely handy, as they feed information about the greenhouse status wirelessly to my phone and computer.  For all those techies out there, here is what we have:

top: Aeon Labs MultiSensor
bottom: Smart Sense Multi Sensor

The Aeon Labs MultiSensor senses temperature, humidity, motion, and light levels.  I have it placed next to my plants.

The Smart Sense Multi Sensor is placed near the greenhouse roof and detects when it opens or closes, as well as what the temperature is up near the roof.

The awesome Mr. Red House has also made a nice app displaying my greenhouse stats in real time.  Check it out at the bottom of my blog page!

the display of my greenhouse stats around 1:30pm today

Our greenhouse is coming along pretty well, but I know temperatures will be even colder in a couple months.  If anyone has other ideas about how to insulate greenhouses, I'd love to hear them!