His… last prop house was situated under a big oak. He had to walk a long ways across his yard and he shoveled for some unknown reason; He’d send pictures of 2 and 3 feet of snow he shoveled to walk there.
He ultimately heated with wood using a stove.
I think that might be because he want to use the greenhouse for propagation instead of fruit production. I don’t think you’d get enough sun on the North or East sides for plants/trees to fruit. I’m concerned about it on the SSW side.
I know it would get hot- maybe on a really sunny day I’d need to crack a window, as venting into the house may not be enough. I was thinking I could use it to warm the house during the day, then use the house (a decently efficient heat pump) to warm the greenhouse at night.
I was hoping to go with a dirt floor. I’m toying with the idea of building low mounds around the outside of the structure to help insulate things. I’m not all that fond of growing things in pots and figured that I could put landscaping fabric and stone on the ground, then plant through it.
Maybe one or two circulation fans and another couple exhaust fans. I need to check to see if they make exhaust fans that seal up during the winter, then open in the event they run.
Sounds like a walk I wouldn’t want to make, especially when it is 1F, like it is right now. Very possibly the coldest night of the year for us here. Hopefully it doesn’t go much lower or my non-astringent persimmons will be at risk. Looks like the figs will be growing back from the ground. I got spoiled by a few winters where it didn’t go lower than +10F.
Bob:
You are right, growing fruit and propagation aren’t the same goals and require a different setup. A greenhouse should be designed around your crop, climate, and goals.
Growing fruit in ground is a yr around setup and requires as much light as possible. That means full sun exposure. Full sun means extremes of heat and cold. To deal with that requires automated equipment and controls.
The reason people put greenhouses for fruit production in the shade or use shade cloth is because the GH isn’t designed to handle full sun.
I’m planting in ground right now. I’ll then put down drip and cover that with black weed barrier for weed control and cover that with white weed fabric to reflect light back up into the canopy.
They do make exhaust fans that open in use and close when not. I’ve got three that are 36 inches. You need at least one air exchange per minute to deal with heat. That will hold inside within 15F of outside. I add on a wet wall for evaporative cooling that keeps inside as cool or cooler than outside. In CT just good exhaust fans might be enough but I’d go more than one exchange per minute.
Your crop may affect design. In CT getting chilling shouldn’t be difficult. I heat to 37-40F at night for increased chilling because 37-48F is best chilling temp. Going with crops that don’t need chilling might be more compatible with the goal of heating the house with excess heat. Harvesting that excess heat does complicate the design but is a worthy goal.
What crops are you considering?
A big part would be things that I’ve given up on or am struggling with in the yard, like cherries (flat out gave up a long time ago), Apricots (they keep dying) and pluots (I get a few great ones, but must get stolen by animals or yellow jackets).
I also have a list of fruit that I think could keep producing far longer if it didn’t get cold. I’m interested to see if I can get them to produce indefinitely, though I may eventually discover they need a break. This would include jujubes (I get second crops on some…maybe 3rd would come?). day neutral strawberries (which also get stolen by animals), and primocane blackberries.
I’ve also got some potted tropicals that I’d want to grow in it. So far, I’ve gotten very little production- 1 small (but good) pineapple.
Maybe figs too, as I seem to recall you getting better production from them, than the in-ground ones. My fig production growing them unprotected outside is hit or miss. Once in a while I get lots from a few, and few from the rest.
Basically everything, which I know could complicate things.
You probably could grow some cold hardy mandarins in there too.
And you can grow PCNA persimmons with harvest till late Dec or even January.
Citrus are very adaptable to a greenhouse even one that’s pretty cool all winter. The main issue is scale and a few other pests. The foliage and branches are so thick it’s hard to get good spray coverage.
That’s a good GH choice. And I don’t think they need much chilling.
Jujube would need a break. And can be grown outside. I’d forget that. Grow what you want but now can’t. My favorites are nectarine, sweet cherry, pluots, and apricots. I’m planting mango but I think that’s a stretch even in a GH in CT.
Stone fruit is what fits that climate in a GH. They need chilling which is easy. Growing season length fits what you’d have.
Here’s something you need to know. Water use in a GH is at most 2/3 of outdoors. If you can’t get water under control the fruit will be watery. If I built another GH it would have a root barrier to hold roots inside. Heavy plastic root barrier material 3-4ft deep around the interior perimeter. And a gutter system to run water off the roof away from the GH.
You think he gonna need an opaque covering no matter what it is? I would think yes…
Just a guess.
I love jujubes, but the main issue I’ve seen is that they only keep for about a month in the fridge, I’m not that fond of the dried ones, and at least one variety I have is borderline too late for my climate, so that would probably make a good candidate to grow inside and give me fruit for another few weeks to a month, just like the PCNA persimmons. But you have a point that I have a lot of productive jujube trees outside (I picked more than 300lbs this year and each year it is increasing). Maybe just one to experiment with 
That’s a good thought. I wonder if disturbing the flow of water would also help keep cold out. It would leave only conduction, instead of conduction and convection (really osmosis) as the heat transfer mechanisms. The only path for water to take in would be from deeper, which is generally warmer anyway. By heavy plastic, do you mean something like 3 mil sheeting?
I like citrus, but am not as fond of it as stone fruit and jujubes. Two favorites are Sumo Mandarins and pomelos, but I’m not sure how difficult either would be to grow.
I’ve have a mango seedling in a pot for the better part of a decade. It has nice big leaves, but never produces. My Lychee and Logan don’t produce either. Just based on taste, I’d far prefer lychee/logan to mango. And they are also far more perishable and a lot harder to find in stores.
Not sure what opaque would mean. I like a covering that diffuses the light but allows as much transmittance of visible as possible.
Remember that fruit in the GH will mature a month or two earlier than outside. The better your GH is designed the longer season you can achieve.
Root barrier is at least 10X that thick. It’s easy to find. And if you trench for root barrier put some insulation in there as well. Or pour a concrete foundation in a 4ft trench with insulation on one side. Concrete would block the roots.
Pomelos would be my top choice for citrus. Probably my favorite and I can buy the others in the store.
I’ve thought about lychee/logan as well.
A good do it yourself root, heat, water barrier would be 4x8ft sheets of 3 inch foam insulation. Something that’s water resistant. Put that in a 4ft trench. And then cover that with 6 mil black poly that’s 8ft wide. That would further protect the insulation with a water proof covering. That or concrete/insulation/plastic is what I’d do.
A great point that I had completely missed. Rather than growing the latest ones, I should be growing early ones and getting them in July/August rather than September (where the first ones ripen here).
I like that idea, though cost may be a factor.
In my temporary hoop house style ones I have often used aquariums as plant racks. The water makes a good thermal sink and as “racks” it’s not in the way as big irrigation barrels in the corner. My favorite are 6ft used acrylic tanks that hold 100-120 gallons. I find them beat/scratched up for free on Craigslist all the time. If you put lids down the water does not mess with the RH at all. And acrylic tanks have top decks unlike glass aquariums. I like that they cool in the summer too.
I was donated a greenhouse this winter from a friend that moved out of state. This is exactly how I plan to make my plant racks. All up on aquariums
Yes, sorry. I meant something not see thru-completely and if not a super size structure maybe a whitish color. I was just concluding that with Polycarbonate that is clear, it’s still not see thru very well and Bob is talking the big money about plexiglass I thought. So, I just wonder what’s going to happen w/o a expert greenhouse consultant what’s gonna happen if he flips the switch and that thing goes over 120 before summer even hits.
I don’t know a damn thing so I’m staying away from this thread to comment on; no doubt about that, guys.
Good luck though Bob.
Dax