Unheated Greenhouses

[R2elk]

@R2elk I love your greenhouse. It's even a great winter porch area!! I've been wanting to enclose my back porch in a similar way. Morning sun on back and southern exposure on end. Those pictures just spark my desire again. Dang you!!

My porch is a 3' raised, sand filled, brick outer and concrete poured on top, for the floor surface. Sounds like a heat sink storage area. wood rails and posts. I think there's possibility!

The outer panels are triple wall polycarbonate with a 1/2" space between the outer panels and the inner twin wall panels. The roof is corrugated polycarbonate panels with polycarbonate sheets on the bottom of the rafters. They were added later to create a dead air space for insulation purposes.

The proof that the roof dead air space works is that snow can be on the roof and the temperature in the greenhouse can be in the 80°s without the snow melting.

A fan driven ventilation system is a requirement. Without it the summer temps will be unbearable.

 

[Mini Horses]

Well mine would certainly be an enclosed sunroom porch where I could start plants, not a true greenhouse! That's ok....would suit me well. There's a solid roof over it, not going away. I actually would prefer windows from rails up, solid clear wall on lower area...I'd have a warmer place to sit and to start plants or chicks.

 

[tortoise]

Greenhouse has been doing well holding nighttime temp 46 - 50 degrees F when we have gotten as low as 28 degrees. This next week will be interesting test. We will have progressively colder overnight low temperatures, forecasted low next Friday is 18 degrees F.

 

[R2elk]

Greenhouse has been doing well holding nighttime temp 46 - 50 degrees F when we have gotten as low as 28 degrees. This next week will be interesting test. We will have progressively colder overnight low temperatures, forecasted low next Friday is 18 degrees F.

The real test is overcast days with freezing temperatures preventing any daytime heat gains.

 

[tortoise]

The real test is overcast days with freezing temperatures preventing any daytime heat gains.

We had one overcast day with no heat gain. It was windy so I left blankets over the domes all day. I was surprised it maintained temp overnight. But that will be different when the ground freezes.

 

[Mini Horses]

Would a 100 w bulb in greenhouse be possible? I've read that just a candle burning in a car can keep temps up...

 

[tortoise]

Would a 100 w bulb in greenhouse be possible? I've read that just a candle burning in a car can keep temps up...

There is an extension cord out there, so yes. I'm not sure I'm willing to use electricity on it.

I got started too late. A book I'm reading describes a winter greenhouse not as extending the growing season but as extending the harvest season. The author harvests through December, takes January off and starts growing again in February. I think that schedule will work for me, but I should have started my leafy green trays earlier.

 

[Britesea]

Yes, most plants do not actually Grow during the darkest months- they go into a kind of suspended state, but you can still harvest them. Also, I seem to recall that Elliot Coleman said that if the plants (greens) actually appear frozen, don't touch them. Often when they thaw, the plant is still ok, and you can even harvest those leaves to eat- just NOT while they are frozen.

 

[tortoise]

Yes, most plants do not actually Grow during the darkest months- they go into a kind of suspended state, but you can still harvest them. Also, I seem to recall that Elliot Coleman said that if the plants (greens) actually appear frozen, don't touch them. Often when they thaw, the plant is still ok, and you can even harvest those leaves to eat- just NOT while they are frozen.

I believe that's the author of the book I'm reading, but I either missed that comment or haven't gotten to it yet.

 

[Britesea]

The 4 Season Garden