Need advice on starting a tropical food forest

Thanks for the reminder!  I acquired many of the plants and I've had them in pots the last year and a half.  One slight hangup is that my greenhouse isn't naturally maintaining above freezing temps :(   Unless I add a heater, it gets down to 20F in there on the coldest nights.  

To skate by last winter I made a mini greenhouse inside the main greenhouse and moved all the nervous plants in there.  Last winter I still had hope of the greenhouse staying warm enough, this year I suffer under none of those illusions.  This winter I did make a temporary greenhouse for them but the quantity of plants will have to decrease in the future.

As for my list of plants, here's what happened:

bananas - they grew well in the ground.  Last year they got 8' tall before dying in the cold.  They actually made it down to about 32 before dying.
avocados - they are growing slowly but seem healthy
mangos - it's struggling and looks like crap but isn't dead yet
pineapples - they stay alive if I keep them warm but haven't fruited in two years so I'm not wasting space on them any more
cinnamon - didn't try since I felt I needed to put them in the ground
dragonfruit - grew slowly (1 foot in first year) but died before I had the mini greenhouse set up
ginger/turmeric - Grow ok in the summer but didn't come back up in year #2.
loquat? - didn't try
papaya? - I planted Mountain Papaya seeds in the ground and a couple grew but died come winter
miracleberry - it struggled for a half a year and died
vanilla orchid - it was doing great but died before I had the greenhouse set up
yagrumo? - didn't try
lemon - they do fine.  Harvested 5 lemons this year
mandarin - Growing well but no fruit yet

My current plan is to reimagine the greenhouse as a Mediterranean greenhouse with plants that can handle 15F.  Need to figure out that list this winter and make my plans.  Along with that I'll have a small part of the greenhouse that can be cordoned off with poly to keep warmer for winter growing.  The lemons and maybe another citrus will hide inside the edge of that area for protection while not taking up too much floor space.

Did you think about having a small meat chicken house inside the greenhouse? They don't need a lot of space and they will add some heat to maybe keep things above freezing. After 4 months of doing heating they can go into the freezer as a good measure for irony

No, I didn't really consider chickens.  I think I need about 100,000 BTU of energy on cold days to keep it above freezing.  I suspect that's a lot of chickens

A few ideas looking at your list of stuff, from zone 9b:

avocados & mangos - if you can keep them pruned to a size where they fruit and also can be moved in and out, I think you might be okay. Especially with the avocados. Mangoes are a tad more sensitive but avocados live through frosts here. I don't have a source, but I read years ago that there is a fruiting avocado in WI somewhere. Maybe worth checking out.
pineapples: I don't think you have a shot. Their season is so long. My uncle has them, he is probably two zones hotter than me and never frosts, and it is just barely warm enough to get a small stunted pineapple every once in a while. They need hot all the time.
dragonfruit: same as pineapple, growth is so slow that interrupting for seasonal cold means it's practically impossible
ginger/turmeric: probably worth trying again, especially turmeric (if you're so inclined). They will do decently enough over a hot summer, and you can also do them in containers to extend the season a bit.
loquat: you should try, if you`re so inclined. They do well with cold, maybe not wisconsin cold but they're a nice plant and I could see you getting one in a barrel to move in and out. The fruit is nothing exciting, compared to a WI apple, say, but it does have medicinal uses and it's pretty enough.
vanilla orchid: my dream, but they need total stability with no fluctuations. I don`t have time for that, not sure about you
lemon/mandarin: both should do just fine!

Thanks Tereza!  I think I could keep the avocados and mango to a 3'x3'x8' high shape.  Would I get much fruit from them if they were kept that small?  Any bigger and they'll take over my mini greenhouse.

I think you're going to have to try it and see. With good dirt and fertilizing i don't see why not! I may be mistaken but I'm pretty sure i read David the Good suggest dwarfing all sorts of trees with some yields; i mean a small tree has fewer branches so you're not going to get buckets but why not (I'm trying hard pruning in my yard with guavas, jackfruit,  and avocado, but it'sstill early days). And mangoes are routinely kept small in farm operations, pretty much the same as apples, otherwise the fruit is out of reach. My aunt has one thats not much taller than me that was just covered in blossoms last time i went there.

I did not see an outside picture of the greenhouse.

Did you berm up earth on the north side of the greenhouse for insulation and thermal mass?

Here's a thread all about it: Mike's passive solar greenhouse

I didn't berm earth up on the north side due to an access path being in that area.

Mike,
The video of my Texas greenhouse was taken years ago before many of the overstory trees had grown in. Calling them "overstory" is not always describing the current height, sometimes I was using it in context to describe the natural growth pattern of certain species. The over story trees are now about 35 ft tall and shade out as much area around them as I will allow through pruning and yearly height and canopy maintenance that is necessary to grow a food forest in a greenhouse. I hope that disambiguates what you saw in that old video.
Best,
Foxxotron

I grew up in Minnesota, and just this year moved to South Florida, so I am still figuring out the tropical plants, but I always dreamed of doing what you are! It's beautiful!!

Definitely papaya and dwarf bananas! A lot of the other things can be pruned hard to keep them under control, or dwarf varieties.

I don't think anyone mentioned ice cream bean tree. I don't know how big they eventually get, but they are a nitrogen fixer and in one year ours is still pretty small. They make pods with sweet fluff like nature's cotton candy! I have heard that coffee growers plant them together with the ice cream bean tree for the nitrogen as well as some shade for the coffee plants. The leaves are a beautiful shiny, deep green and I would grow the tree just for the foliage alone. I am still waiting impatiently for the first fruits!

My dad and I were so excited and planted TONS of fruit trees before we really knew what we were doing. We have run into so many problems with the pests and diseases that we didn't have in Minnesota. I bet you would have a lot more luck with them in the greenhouse without the pests and diseases, as well as having the ability to control the environment! Some day...

Is the Mitchell Park Conservatory in Milwaukee still open? I made many visits to the domes while growing up. The tropical one was my favorite. If it’s still there, it might be worthwhile to chat with the people who care for the ecosystems in there.

Hi Mike and followers,

Congratulations on your project!

We are soon moving to a tropical country.

I am unfamiliar with tropical farming, so I wonder why you need a green house in the tropics.

Thank you,
Anouk

Hi L, yes it was there two years ago when I was last in the area.  I like the Como conservatory in Minneapolis even better.  Both are a long drive from my location.

Anouk, I don't live in the tropics.  I live in a frigid temperate climate so I need a greenhouse to get closer to tropical conditions.

have you thought of trying strawberry guavas, prolific and desirous

Mike
I just googled the Como. What a treasure! The “big idea” behind Mitchell parks is really the  domes themselves, finished in the early 1960’s.  Fun fact:

Shape
The world's only conoidal (not geodesic) glass house; the unique shape allows a better angle for solar heating and more height for tall trees. (https://milwaukeedomes.org/domes-technical).  

But the Como - that looks like  a whole world unto itself. Thank you for posting about it.  If/when I get back to Wisconsin (Mikwaukee is my hometown) I am definitely arranging a side trip.

I hope you continue to post about the progress of your project.  I was surprised to find that I can grow figs and pomegranates outdoors here in the Willamette Valley, but I do dream of growing my own avocados and  papayas. Especially the papayas.