So I built myself a small greenhouse.  I've never had one before and devised the plans to fit my small backyard arrangement and from information found on the web, pictures and videos.  It's about 7' x 4' and 5' tall, has two doors on the front that open outwards and a hinged lid.  Shelf inside made with PVC slats and sized to fit 12 flats of Stuewe 4x4x9 (144) Mini-Treepots.  The base is constructed with pressure treated wood.  The bones are 2x3 construction with a coat of white outdoor paint.  Everything is screwed together.  The outside is skinned with reinforced plastic sheeting. All door and lid seams have been weatherstripped.  It is standing on a concrete pad up against the back of the house with a southwestern view more or less.  It is in full sun from about 11:00 on.  Installed a Univent automatic vent opener to keep it cool when the weather starts to get a little warmer (cylinder removed in the picture).  Using a small space heater to help warm it up for now. 

      

It has been overcast and cold for the last few days here in Staten Island.  The nighttime outside temps  have gone down to the low and mid 40's.  During the day the outside temps have been in the high 40's and low 50's.  Without the heater, temps in the green house are about 5 degrees higher than outside.  With the heater running, temps are about 20 degrees higher than outside.  With nothing in the greenhouse the humidity levels have been about the same as outside more or less.

My plan is to add cuttings to 5-1-1-1 mix in mini-treepots and put them in the greenhouse.  I know the conditions are not ideal right now but the warming trend is on and the 10-day forecast is showing daytime temps in the mid to high 60's and nighttime temps at 50 and above.  My expectations are to start transitioning out of the greenhouse by late June or early July.  My goal is to have plants that will be strong enough to be stored and make it through next winter in a heated shed.

I will be moving forward with my plan today but I'd like to hear some thoughts or criticism on the set-up.   With a 10-day forecast like that and using the heater, will I be 'in the zone'?  What should I expect when the sun comes out and really starts to shine on it?  Are there any reasons why the green house wouldn't work?  Would you change anything?

Have at it!

I think you did a great job!  I have one of those flimsy el cheapos, so it never gets used.  Congratulations on the great job!!

Suzi

Job well done Danny!  You're gonna love it!  If I were you, I'd go ahead and start on another one that can sit on top of this one.  Why? Because every person that I know that built a GH wish they had built it twice the size!  I have one that's 6'x8'.  Just 2 weeks ago, I bought another one.  It's at home waiting to be built.  And it's 12'x20'!  

On your GH, go ahead and call up Grower's SUpply and order some shade cloth.  Trust me, you will need it!  I have 70% sun block shade cloth but you will need 90%.  Once that sun hits it, it will be 20 degree warmer inside and vents isn't enough to keep it cool.  And get some wasp spray!  Every year, this time I fight wasp like crazy.  They will put a nest where you least expect it! 

Looks super, I may have to copy.

Thank you for the compliments, everyone.

It's hard to think that the greenhouse will be that much warmer on its own when the temps are still low outside.  I will take your advice, Dennis, and purchase some shade cloth.  I wish that it could have been bigger but space is limited in my tiny yard.  Maybe I'll get rid of the shed one day and replace it with a bigger greenhouse.  

Nice work, Danny. I made one myself last weekend, using mostly free materials. Will post photos this weekend.
Where did you buy the reinforced plastic, and how much does it cost?

Looks great Danny. For me, the value of the greenhouse will be in the future, mine is 8ft tall and I plan to get as many trees as possible in there as my plants grow up, so as to get those leaves breaking bud as early as possible. Temps in sunshine with heater on can easily get near 90F during this past month. Cloudy and cold like today, it is 70-75 w heater on. Get down around 60-65 at nite. I have not opened vents yet but I will next week. Also, fighting off a gnat infestation, and had scale last fall in there, so beware of critters.

Mat - Got the reinforced plastic  at a yard sale a few years ago.  Huge roll of 20' x ??.  Looks to be at least 100' long.  Paid $8 for the roll.

Rafael - Do you think having plants in there has anything to do with raising the temperatures?  Even with the heater, mine seemed pretty cool.  We'll see tonight.  Potting up right now.  :)

Very nicely built my friend. I think we will start getting warmer this weekend. I was shuffling a bit last week when it was warmer but have left the plants out the last 2 chilly nights. I just can't baby them any longer. They are out and are not going back in.

Hi nycfig,
Nice job . Is that greenhouse sealed once closed ? It seems to me I see spaces around the door that would let the cold air and cold wind come in.
With cold temps outside, you need the greenhouse to be sealed once closed.
I use one made of 4 reused windows + one plastic sheet face for raising my tomatoes from seeds .
Last year I had some cuttings inside after the tomatoes, and those cuttings loved it there.
For humidity, put inside a bucket full of water in the greenhouse - it seems to me that it helps a lot.
If you have some space left inside your gh , try to raise tomato seedlings inside. You will learn a lot on how effective your greenhouse is at keeping the temps in the safe zone.

Coop - Thank you.  Hoping this is the last cold night.

JDS - Thanks for the feedback.  I'm glad the cuttings loved it in your greenhouse.  Makes me feel better.  What looks like (dark) spaces around the doors and lid is actually weatherstripping.  In hindsight I should have used grey instead of black for aesthetics.  It seems to be sealed up pretty tight.  I like the bucket of water idea and will add that in the morning.  Thanks.

Danny

I don't think the plants do much to raise temps. I sealed cracks with silicone caulking, at floor level, since my greenhouse is not on a base but on cement tiles. Seal it up good. I had a pot of water in the GH and nasty pink mold formed all over it, doesn't seem like a good idea. Get a mister of some sort and mist the leaves with that, the greenhouse will seal in the moisture and it will stay moist a bit longer that way.

Good Job Danny!

Looks great Dan! I absolutely agree with snaglpus. Mine is 9' deep 13' wide and 7' high and I wish it was bigger. I can't wait for it to warm up at night so I can move my tomatoes and bananas outside to make more room for peppers and eggplants.

You did a marvelous job on your gh!! You will get a lot of enjoyment out of it!!

Looks great - bet you will want a larger one soon! :>)

Outstanding!!! Nice job.

Thanks again for the kind words, everyone.  Had a chance to start potting up cuttings and did about 50 cuttings.

 

They seem to be happy in there.

The vent opener attached to the lid of the greenhouse seems to be working well.  Monitored the temps in there this morning.  As soon as the sun hit the greenhouse it shot up from 69 degrees to 98 degrees in a matter of 15 minutes.  The temps leveled off at 95 degrees and the lid was wide open.  Finally realized the sun was hitting the wireless thermometer directly and giving me an incorrect reading.  Anyone know of an accurate thermometer that will give me a correct reading, even in the sun?