small greenhouse heating question

This time of year it is close to 50* overnight many nights. During the day this little puppy will heat up to 100 quickly, but cools off so fast after the sun drops lower in the sky by mid afternoon.

Anyway suggestions on how to hold the heat inside? I do have a small electric heater, but that might get expensive. I just don't want it to go below 50-55* overnite. Then I can put out some pepper and tomato starts I have going in the garage.

Then of couse they might cook at 90* during the day.

Any help would be greatly appreciated.

Thanks,

Steve

We use black 5-gal pails filled with water--or they could be green--during the day the water will heat up, and release during the night. In your climate, a few may be all you need. You could put plant shelves on top of them.

I've friends who saved all their green "Real Lemon" bottles. They built little ledges along the walls of their g.h. and put the water-filled bottles on that--they didn't look too bad, and my friends swear it helped with cool nights.

Thanks. I was thinking some way to store the heat.

Wonder if I can find a small black garbage can...

As you can see my puppy is small! NO doors.

S

One way to solve the problem is to insulate to keep the heat in. I think if you cover the whole greenhouse with plastic and make sure it is on the ground all around you will need a lot less heat. Water bottles probably won't store enough heat and it will cool very quickly. A stone floor will probably be better. Also string some christmas lights inside -- that will probably give you enough heat. If the picture comes out (my first try!), the box in the snow was made from foam insulation with an outside layer of plastic. I laid three strings of Christmas lights in the bottom and put the seedling trays directly on the lights. Now 20 degrees out and 70 degrees in! During the day when the sun was out I would take the lid off leaving the plastic on. On a really nice day I took the plastic off.

Also, if you have room in the bottom for a cement stepping stone or pea gravel or something similar, that might help too. They also release a bit of humidity when it is warm. I can't tell what your GH is sitting on so you may already have the first part covered. :)

Right now my GH is sitting on the new deck boards. I could put in the stepping stones and then cover with some black gardening cloth I have. I wonder if there is such a thing as black pea gravel? That might loook a lot nicer since the GH is on the deck. Of course I could wash all 16 window panes too!

Steve

You'd be surprised how long the water holds its heat--and it releases it slowly. Remember, we're talking only 50F outside temperatures--not very cold. Experiment! Check the water temperature when the sun sets and again the next morning. Good idea about the extra layer of plastic; it would make a huge difference to retaining the inside heat.

You're right about not wanting peppers and tomatoes to go below 55F but I think your bigger concern, Steve, is the high temperatures during the day! Tomatoes don't like to set fruit at temps over 85, and probably peppers are the same. I imagine you've arranged for good daytime venting? Just remember to button it all up before the sun starts to fade.

Do you have a max-min thermometer? It's really a good idea for any size greenhouse. Establish your temperature fluctuation before you put your plants in.

I've been reading that green works as well as black--maybe a non-toxic paint spray for the pea gravel????
But really, the natural colour is not at all offensive. Just doesn't absorb heat as well.