Fruit Trenches: Cultivating Subtropical Plants in Freezing Temperatures

There's another great research article out from low-tech magazine!

The page goes into much more detail than I can here, but the jest of it is between the 1920's-1950's the Russians developed a system for growing citrus in sub-freezing climates using a number of innovations including cold-hardening, trenches (of course), and forcing the trees to grow very close to the ground.  Some rather extreme, though interesting, ideas!

Neat!

Around here we'd call those 'seasonal ponds', unfortunately... unless I built a giant berm of very well drained soil and put the trench on top.... hm.

Thanks for posting that K!!!  So they could grow citrus in areas where it got very cold.  And the trenches were just one way they did it.  

I'd wondered about digging a hole to put a lemon tree in on my property but it would've been a miserable failure the way I was thinking of doing it.  This article gives me some serious hope.

They didn't say how they incorporated the small amount of glass into the trench design.  I'm wondering if they just spaced the boards apart a bit and laid glass on top of it and then the mats on top of that.

Or for my situation, I wonder about a layer of twin wall poly as the roof (along with boards for support) starting when the first frosts are expected.  Then it will be covered by snow for Nov-Mar and I can open it back up in the spring...

They said that roofs were sloped at 30-35 degrees but the picture made it look much flatter than that.

Thanks!  Just found this myself... and I think some radical pruning was used in some places... plus 'hardening' varieties by growing from seed in harsh climates, etc.

A government department in my region of India promoted sunken greenhouses a bit like that one year, and our school tried it out. I didn't like two things about it. One is, the south wall of it cast a long shadow in midwinter. Another thing I didn't like is that entry was by peeling back a corner of the top and climbing down inside, and then ours was too low to work in comfortably. The advantage of course is the heat of the earth.

I believe the point of these trenches is to have them open for spring/summer/autumn and then cover them for the winter.  Since the trees are kind of dormant in winter you shouldn't need to access them much, if at all.  And the shade from the south wall also wouldn't be an issue in winter.  

I assume they accessed them at the end via a series of steps or ramp that was also covered for the winter.

If the roof was really sloped at 30-35 degrees, then it would let decent sunlight in around the solstices.  But the sketches sure don't seem to show them at 30 degrees.

I was looking up cold hardy citrus from Mckenzie Farms and the Owari Satsuma sounds like a candidate for this.  Good down to 12F.  I'd imagine that tree in a 6' deep and 5' wide trench with a blanket of snow above it would easily get through my winter above 12F.  I think...  

I built a climate battery greenhouse in Anacortes WA, pretty far north, but not as cold as Montana. It worked great March through October, but not in the other months because we just don't have enough sunlight to warm it up during the day...also a lot of grey days here as well.

These greenhouses do work well on the more eastern locations that are further south but still much colder than we get here.

Just something to factor in when considering experimenting with this sort of thing is, "do you get enough sunlight for these clever techniques to work?"

https://www.buildingconservation.com/articles/pineapples/pineapples.htm

Pineapple pits at Kew Gardens in England.

I think this is the most important take-away from the article (at least for us northerners with little sun in the winter months!)

Citrus plants tolerate very low light levels for 3-4 months per year, provided that the temperature of the air in contact with the crown is maintained between 1 and 4 degrees Celsius. At this temperature, the metabolism of the plants weakens, which improves their resistance to cold.

Coolest thing I've seen in a while

this is a better way

Meme grant wrote:this is a better way

Wouldn't say "better" - maybe "different" fits there. More modern technology reliant (meaning more expensive money-wise) and doesn't take advantage of many of the things happening there with the russian trenches like open-air growth and selective breeding.

I, for one, prefer food grown in natural rain with naturally occurring pollinators and predatory insects taking care of my pests. Not going to get that as easy in a modern greenhouse method like the nebraska citrus. You still get local citrus grown in (ostensibly) real soil from it, so can't complain

I've read that some people train figs to the ground so they can better protect them in the winter in cold climates and the bit about bringing the stem up roughly 10 inches before "sprawling" the branches got me thinking. Super neat stuff