I'm building a 3rd greenhouse to go along with my existing 12' x 24' x 6.5' aquaponics tunnel and 14' x 55' x 7.5' semi-pit tunnel.  This new pit tunnel will be around 16' x 75' x 9.5' and about 4' deep.

This time, instead of doing all of the digging by hand with a shovel and wheelbarrow, I rented a Bobcat for the first day.  After the 1st day, I thought, "Eh, that's enough help, I'll just do the rest by hand."  Now, 3 weeks and many blisters and sore muscles later, I think another day with the Bobcat would have been a good choice!

Here's what the trench looked like after using the Bobcat on the first day:
 
 

And here's what it looks like now:
 
 
There's still a lot more to do before it's done, but it'll get there. 

Great project! I was considering doing this for my tiny 6x8 greenhouse to help regulate temps. Good to see that it works nicely. You can probably extend your fig harvest this way too.

Thanks for the kind words, Brian.

Yeah, these structures give me a really extended season.  I'm still ripening fruit in my 1st semi-pit tunnel, and none of the figs in there seem to have been bothered by this current cold snap.  I think we're going to have a relatively mild winter, so I don't think those fig trees will go dormant until late December or January this year.

Super way to build a green house with extended benefits of deep dirt floors and dirt walls. Nice concept.

Very nice! 

The bobcat was a great idea.  Can't believe you tried to dig that by hand.  Crazy.  Looks like a really good start.  Good luck.

How do you handle water with heavy rains? Does it collect in the trench?
Do you install some kind of drainage?
If I dug that trench in my area it would be a pond much of the year - heavy clay under a few inches of topsoil.

James I'm considering building that type of greenhouse too. Which leads me to the same question as Ed, How do you keep the hole from filling up with water. I would think the ground water would wick it's way in through the walls eventually causing them to crumble also. Do you have a type of drainage under the floor and sides?

That's a great project. 
Thanks for the posting and please keep us posted on your progress.

It looks like the first few feet of soil is really nice black dirt.    Are the vegetables and bananas located at different sections of the aquaponics greenhouse?

Man I wish I had a bunch of land out back of my house.!

James,

Very impressed.  Great project and looks so well done.  

Nice setup. I've considered the design shown here but the cost has me hesitating to pull the trigger: http://www.greenhouseinthesnow.com

How did you go about designing these? Did you find plans somewhere?

Thanks for the nice comments, everybody.

Here's the one I'm working on.


It's 5' X 20', 3' deep. I'll enlarge it next year, but I'm just trying to make a place to get the plants out of the house for now. I'm digging a trench to it now, for access and drainage. I'll post more when I get it further along.

How long does it take to grow bananas. Is this just a labor of love. Or are you able to turn a profit I know a couple of people who started aquoponics on a large scale and just say it is not feasible right now to turn a profit. They also bought top of the line stuff And it seems you have spent there bare minimum. Besides your back aches.

James
This is an amazing thing you accomplished with your aquaponics greenhouse and pit greenhouses. 
Who would have thought you could overwinter bananas outside in zone 6a. 

James, I would like to know how you keep them heated in the cold weather. Also, I can't really tell how deep the trench is. I am in zone 6, too. I have a simple 12x25 hoop house and half of it has a double layer of plastic. With the double layer of plastic it doesn't need much heat - just a simple space heater that cycles on and off. I would love to see pictures of your other greenhouses, sometime. I have looked at some info on aquaponics but the heating issue just seemed to expensive...

Thanks, James! That gives me a lot to think about. Don't know if I'm up to digging that trench but maybe - Good soil here and no clay for at least 2 feet. I wanted to set up a small lean-to green house just for seedlings this spring but I may completely change my plans. What kind of fish are you raising (if you don't mind my asking....)?