You may have already mentioned this, but I would add pollination as a significant challenge. In the winter and spring when food is more scarce I get a lot of ants which is great, but I haven’t figured out what to do with flowers that bloom in the summer.
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Alfalfa leafcutter bees seem to be the best option
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I use bumblebees for stone fruit pollination. A hive lasts about 4-6 weeks. I’ve thought about trying alfalfa leaf cutter bees. @Phlogopite have you tried them? My main concern is that they won’t hatch out when I need them. Mason bees were a no show. I tried them the first year.
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I haven’t done it myself, just read reports. You might be able to keep a bunch of eggs chilled for most of the year and place them in the GH when needed, hopefully each generation would lay more eggs for you if given some reeds but I’m not sure
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Thanks! I think managing the temperatures of any fruit crop is critical, and even more so for plants grown inside. You have really come up with some ‘cool’ solutions, and I’m taking notes. I have some small citrus which I winter over in an unheated crawlspace under the house. Low temperatures there brush against freezing sometimes, but all of them make it, even keeping their leaves though it is pitch dark. Humidity stays over 90%, but there is very little condensation so fungal problems are minimal. Some plants actually suffer from drying out in pots.
One other question. Do you use the white ground cover to help improve light levels, or is that just incidental?
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I’ve got down black weed barrier for weed control. Then on top of that the white material for improved light conditions. After 20 years a few weeds are invading the edges in places. Nutsedge and Bermuda grass are both very invasive.
On another subject, potted trees are easier to manage and much more flexible. They can be moved around, removed, or added at any time. In ground trees have an advantage in fruit quality because the trees can more easily sustain a water deficient. But in ground can be too vigorous and difficult to manage. You can get a lot more trees and different things in a GH using pots vs in ground.
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I can see trying it both ways. Not that I have all the room I would like (mostly site limitations) but keeping a few risk - averse potted trees would be a small bit of potted stuff. I think planted trees would take a lot less time to water. Do you use an irrigation system? Since I have such shallow soil even planted trees would be in some sort of raised bed.
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I’ve got drip irrigation under the weed barrier. My current planting is only 6-18 months in the ground. It’s actually the third planting. The drip lines are pretty close together. About every 18 inches. That’s twice as close as my first planting.
I’m still trying to work out how much to water. I think it’s going to come out to near 2-3 inches per month. Two inches a month is about the number I have in my head from the first planting. That’s not much for an environment where it’s 90F high every day for 6-8 months straight.
Watering is easier in pots. That usually works out to once every day or two after full leaf.
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Good timing, I just came in from watering pots. It’s in the 8o’s here, and if we get sun it will be every day, for sure. And as you said, the plants are often under more stress because I can’t always be on top of it. But in rainy stretches it can be a week between, since these are all outside. In the commercial greenhouses I managed (all potted plants) the watering took one person all day, almost every day. Hanging plants got drip irrigation, but all the stuff on benches was moved too often to make it worth doing the drip lines. I’m impressed that you’ve gotten your planted trees down to a regular schedule.
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Thanks for sharing lot of good info here!
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I just started leveling my greenhouse floor and putting in 6 spots to plant in ground. I plan to put 2 figs, 2 olives, 2 avocado in ground.
I’m at 2k elevation, a little more maybe. high desert so summer cooling in there will be just as important as winter heating. in winter I cover with a concrete tarp outside on the north/east side, and a solar pool tarp over the entire thing. I use reflectix on the inside long west/south facing side, and heat mats under some bigger pots and hot lights in the day - I’ll supplement with a small space heater on the coldest nights.
I’m not sure how to cool it well in summer. doors and windows wide open, a fan- and a vent up top. but it’s 110 outside! then it gets up to 120F inside no matter what I do. I really can’t afford to use AC and we have dry dry drought here. so I’m at a bit of a loss for next year.
it’s a 11x13 foot plants, with the sloped roof (we get snow and wind storms).
what’s cheapest to use for cooling? the greenhouse steps down about a foot inside from the outside ground.
it runs north/south, at a slight angle. it does get morning shade in summer, no shade in winter. leveled with native soil, sand, and I’m using some cinder blocks to set shelves on later. it won’t be ready until the fall this year, I’m mostly concerned for next summer
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Your chilling cycle sounds like just a normal winter in my greenhouse, except it’s for 3-4 months or more. It’s no wonder most of my mangos died last winter. But a few made it through ok.
It’s funny how the avocados flourish with that kind of winter, but pretty much everything else (including most citrus) really struggles. Luckily for me, it’s only the avocados I really care about in there.
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I guess there’s no easy way to modify the greenhouse so that the panels can be removed in summer? That’s about all I can think of if you want the stuff inside to survive summer and not be under such thick shade cloth that it can barely photosynthesize.
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the thing is a nightmare to put together/deconstruct. I could possibly pull a panel on the sunny side most easily, the vent is on the opposite side top. but again it’s 110 outside so, it’s always going to be slightly hotter inside. it’s a real dilemma because it needs to be shut tight and insulated for winter.
I used to have a hoophouse there instead and taking the plastic up and down twice a year was so awful. a friend (who is a bit rich) helped once and went and got me the greenhouse as a gift.
ye olde hoophouse being deconstructed for summer one year. lots of plastic waste- bubble wrap inside in layers, big greenhouse plastic layers to cover, etc etc. and smaller- 8x14 feet
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Where are the photos??
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The cheapest cooling especially in a dry climate is a wet wall and exhaust fans. My GH is 32x54x16ft tall. It has a 4x25ft wet wall on the north end and three 36 inch exhaust fans on the south end. It has held 91F high every day all summer running just two fans and the wet wall part time. We’re hotter and more humid than Spokane. So, yours would work better than mine if properly built.
People build wet walls by themselves. In a 11x13x8ft GH you’d need an exhaust fan of about 1200 cfm or more. The standard is one air exchange per minute. Without the wet wall I’d go twice that, 2500 cfm. That would hold inside ~ 5-10F warmer than outside.
My 36 inch exhaust fans have only 1/3 hp motors. The cost to run them isn’t much. Even in summer it’s only one fan running for about 15 hours a day, two the rest of the day.
It’s the wet wall that allows such efficient chilling in winter and cooling in summer.
If anyone needs more help contact me.
Evaporative Cooling for Greenhouses - J&D Manufacturing (jdmfg.com)
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Another consideration for in-ground fruit tree growing in a greenhouse is root control. By that I mean take measures to keep all tree roots inside the GH. Either a concrete footing around the perimeter or more economically a root barrier. Dig a trench 3-4ft deep just inside the exterior walls and place a root barrier in the trench. They make root barrier material of thick poly about 30-50 mil.
If one did pour a concrete footing, the weed barrier on the inside of the concrete would be smart.
Water control is everything when it comes to stone fruit quality. So, maximize your water control from the start.
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hopefully you dont mind me asking you about an overwintering structure ive had in mind. its intended goal is to be used as a storage space to keep my potted fig collection alive in winter.
i want to use standard construction materials at their standard sizes. it would mostly be built from modular 2x4" panel sections at 4x8’ sizing. these would be wrapped like a present in 1 or 2 layers thick of standard 6mil poly. im not worry about longevity. should be easy enough to rewrap individual sections as needed. plus its mostly for late fall/winter/early spring and would be taken down for when the weather is nice and be able to be stacked flat for storage when not in use. i dont have the sides done up here but would be two other modular sections and two triangles. the principal would be to use the 3.5" air gap of the 2x4 as insulation. it obviously wouldnt be perfectly sealed but i would use a clear tape for seams thats also easily replaceable. would probably need supplemental heat in the coldest of times here in z5. i havent really though about how it would be in contact with the ground yet.
do you think something like this would be viable?
I ended up grabbing a swamp cooler on sale, it can sit on the ground. I have a fan. it’s real dry here so it should work fine
I still keep delaying putting in the roof vent but there is a window above each door on the ends
now I’m just going to try to figure out air flow and how to not waste the cooling. I’m planting olive, fig and avocado into the ground along the east wall of the gh
getting ready to pull the insulation and roll it off the greenhouse. shade will go on instead
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Two layers of poly with an air gap is not much insulation. It is better than nothing and with some heat on cold nights might work. I’d use over wintering poly not clear. Over wintering is nearly white and designed to not heat up as much during the day. If you could cover the fig pots with heavy duty frost blanket inside the shelter then you might be in good shape. Just be careful or mice/voles will eat up your plants.
Real insulated panels would be a lot more insulation.
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