Im in seattle and grow passionfruit, taro, sugarcane and guava and it does fine here. Gets a bit beat up over winter at 50 degrees but they recover like a champ come spring and they have produced for me.
I also have pineapple and banana, niether of which have produced but they seem to grow fine in the greenhouse.
What else could i try that stays small-ish and produces at a young age?
How about citrus and mango. Citrus isnāt a true tropical but takes cool/cold winters like a champ. Mango would survive with 50F minimum especially if days warm up above 60F. Start with a seeding, preferably from polyembryonic variety, not a grafted tree. Seedling grows better while young.
I have citrus, lemon, lime, keylime, kumquat, limequat, grapefruit, orange, and then lemon/strawberry guava (Psidium littorale) and an avocado which i keep with my citrus - they all do fine.
grafted Mangos, never again. 3 died to date. They do grow pretty true from seed though no? how long do seedlings take to produce in your expierence?
Im south of you, california side of the oregon border, coastal, and have a happy little inga tree that does well outside spring through fall. It is in its third year and should have fruited this year except two winters ago i experimented with leaving it outside in the winterā¦first time we had real snow since the seventies, it died back significanly but rebounded like a champ. Last winter i pulled it into the greenhouse, it was very happy. If you want to play with an ice cream bean tree it could work for you.
Seedling mango of polyembrionic varieties may be true from seed. Supposedly one from each seed is a cross and the others are true. Iāve got a number of seedings but none more than two years. So no fruit. In your conditions it might be 4-5 years at best.
If your grafted trees have died seedlings are going to be a stretch. Mine have suffered chilling injury in conditions that donāt phase citrus.
Have u tasted the fruit? I bought I read the fruit taste is meh and has a texture of cotton?
I have a bunch of seedlings if you want any. Iāll be testing 2 in my greenhouse but planted out a whole clump of them outside to see if the roots will survive the winter.
The flavor was not bad, and the texture is juicier than ācottonā implies, though it is sorta fluffy. My biggest complaint was how the polyembryonic seeds broke apart if I tried to use my teeth to separate them from the flesh. But instead, I started cutting off the flesh and that worked better. Iād cut them in half and the seed came out easily.
If you ever want scionwood for the avocados, youāre welcome to PM me any time youāll be in West Seattle, I usually can spare some. I have found they donāt love being in a container long-term, though. Iām guessing your greenhouse doesnāt have a dirt floor that you can plant into?
I bought a little cado and Gwen avocado tree and one died pretty quick forget which one thought off the top of my head.
I was gonna try to graft onto it when it gets a bit bigger.
Have you gotten any avocados to set ? What about ripen?
The trees are all pretty young, mostly less than three years from grafting, but the tallest are around 10 ft tall in the ground in the greenhouse. Those initially set many dozens of fruit, but only one is left hanging, I posted a photo of it a couple weeks ago here:
If youāre interested in joining the avocado breeding project, you can read more about it here:
I have not. My DIL was raised in Hawaii and says they can be amazing or they can be spitters. If grown from seed there will be varibility in quality. Since you are basically eating fluff I see it as a curious novelty. They can reach 60 feet if planted in ground so i dont expect to have it for many years imagining it becoming very un happy long term in a pot. If you have the room to play with its worth considering. Im intrigued by the possibility of growing my own vanilla fairy floss.
I have 3 mangos in 25 gallon pots that have survived Colorado cold in an unheated garage? I brought them over to Olympia with me. I feel like the bigger the tree, the colder they can withstand. I had a Mahachanok seedling that survived 34 degrees in Colorado until i tried to transplant it 
it was a seed i stuck into a pot for the worms to eat but it sprouted in the fall and hung on with just 6 leaves throughout the winter.
What type of passion fruit do you have?
All of my plants are in pots too and no greenhouse but i roll them into the garage when it gets cold. Sometimes i turn on a small space heater but only if the temperature is supposed to go under freezing.
I have a Mexican Guava thatās also survived Colorado cold as well. It died back down to the ground but itās put on about a foot of growth now. Colorado cold = -10 to -20 degrees 
donāt know how theyāve made it but theyāre making it! Also have a Ruby Supreme Guava as well.
Ooo! You should try pineapple guava! Those are champs. I got all of mine from Restoring Eden in SeaTac. Absolutely loved my 2 that i got last fall thatās also survived Colorado cold so i went and got 4 more a few weeks ago.
Have you tried pomegranate before? I had one i grew from seed and neglected in SeaTac but it hung on until my momās dog ate it to the ground. It started producing after 3 years (from seed) and i was able to get the cutest medium sized wonderful pomegranate from it until her dog got to it.
**edit cause auto correct likes to add in extra words for some reasonā¦
Thereās no need to put those in a greenhouse here in Seattle/western WA, feijoa grows just fine outdoors.
I have a Meyer lemon and a Bearss lime and both are ridiculously productive despite being pretty young and in small pots. Itās comical how many lemons will hang off my plant at one time.
I donāt know why i didnāt see the rest of the āin a greenhouseā part. My badā¦ yeah those do great outside hereš
Citrus grafts are extremely prolific. You can graft a less than one year old sour orange with basically any fruiting age citrus, and it will start producing within the year. I was just at Walmart yesterday and they got an aisle of 1g-3g citrus trees and all of them are fruiting.
If you like citrus, they are a great greenhouse plant. Will also protect the plant from the 100 different diseases citrus can catch.
I glanced through this thread and I didnāt think I saw Miracle Berry mentioned. Maybe not a true tropical but worthwhile I think. Phillip Conservatory in Pittsburgh has an established bush in their greenhouse type area, but it likely stays warmer than 50 F. If anyone is fruiting it, Iād be interested in your experience.
Miracle berry in my experience and others I wouldnāt recommend. They always die randomly for seemingly every different reason. Too low PH, too high Ph, too much water, not enough water; and everything in between.
I will recommend a Sapodilla, specifically a Silas woods. It stays small, and mine seems relatively bulletproof thus far. You may not get enough heat in the pnw for many things I would recommend however. Starfruit (Kary) and Acerola fruit well in pots. Maybe some Eugenia- Surinam cherry, Grumichama and Cherry of the Rio Grande along with a laundry list of more rare varieties. They are wonderful plants. If you water with rainwater especially they will thrive. Iād say try some Eugeniaās they have become quickly my favorite genus
Anybody that wants to expand in citrus or fig I got your answer. 25 container citrus, all tops varieties and some of the finest fig varieties, come and get them. I am bailing out of growing fruit trees, way too many variables, weather (PV), drought, my age tells me itās time. Btw all free!!!: forgot Tornado with a massive hailstorm, what else!
Omg 
if only you were in Washington state or i saw this when i was in Colorado
I tried to grow ice cream bean a few years ago and it died. I will try again once I taste the fruit assuming itās tasty. I almost ordered some a couple Of months ago but it was like 10 pounds. I just need one to taste.