Mini Greenhouses

Gardening probably isn't the best hobby for me to have.  I don't have the patience.  When I read a seed packet and it says, "Germinates in 18-21 days." I think, "Gah!  That's like forever!  I want to put seeds in the ground and see stuff come up tomorrow!"  (Note:  That 18-21 days is under ideal conditions with soil temps of 70-80* and proper moisture.  It takes longer if it's cooler.)

The other problem with gardening is winter.  Stuff just doesn't want to grow when it's too cold out.  While I can't do anything about germination times, I've found that there are a couple of solutions to the winter problem.

1. Move to where it's warmer.  We did this in 2010 when we left Pennsylvania and relocated to North Carolina.  While it is warmer here, we still get 2 months of winter.
2. Get a greenhouse.  

There are plenty of places on the internet where you can buy pre-manufactured greenhouses.  There are little 4-shelf units and great big hoop style ones.  Of course the issue with a big structure is that you need a place to put it (and there's the cost).  I have a lot of trees, which means I have a lot of shade.

So I decided to see what I could do with a mini-greenhouse.

This is what I came up with.  I built it out of 2x2 stick lumber and plastic drop clothe from Home Depot (or was it Lowes?).  Total cost was $13.  I threw the thing together pretty quickly using 2" screws and a reciprocating saw.  

 

I stapled some black felt to the back in the hope that it would absorb more heat from the sun.  If you look closely you can see kale sprouting in the back container.

I also used some twine to string up an old 120mm computer fan for air circulation.

 

I bought digital thermometer with a wireless sensor so I could keep track of the temperatures.  The pictures below show the ambient temperature outside as well as the temperature in the greenhouse.  There was a 30* difference at 9:30 AM.

 

A difference of 20-30* seems to be the norm.  I've seen the greenhouse get into the 80's when it was 60* outside.  

The biggest problem I have right now is retaining that heat.  Overnight the greenhouse gives up all of its heat and is the same as the ambient temp early in the morning.  I haven't come up with a full solution that I'm satisfied with yet, but I'm working on it.