The warmth from the foundation could certainly have helped the underground portions (corm) to survive, but it does not seem possible that the above-ground portions would have survived the most recent winter, even if the house lacks insulation and the plants were leaning against it while the heat was on full blast.
Now we have had a number of winters that were mild enough for a banana to have its p-stem survive in the last few decades, but we’ve had deep multi-day hard freezes each of the last three winters (in my yard that meant winter lows of 16°F in Dec 2021, 17°F in Dec 2022, and 15°F this January). Are you absolutely sure the pseudostems didn’t regrow anew after each of these winters? You’re making an extraordinary claim, so I hope you’ll forgive my skepticism.
Looking at this chart I made a few years ago, some years where a banana might have survived above ground in a protected location (like against a heated building) include:
1991 (26°F low)
1999 (30°F)
2000 (27°F)
2001 (26°F)
2002 (25°F)
2003 (25°F)
2012 (26°F)
2015 (25°F)
2020 (28°F)
But those years are the exception (albeit the type of exception I keep hoping we’ll get again soon to help my avocados size up for once). The other years since 1990 have all generally been below 25°F, a threshold where banana p-stems start croaking even in sheltered locations without active protection (wrapping with insulation and string lights).
Yes, I’m sure. The smaller ones do die down some years but for the most part, the big ones survive and fruit every 2 years. I remember hoping over there once during late January/ early February and distinctively seeing snow on the leaves and asking about it. They’ve definitely fruited before because that’s how my banana obsession started, it was with the giant thing of bananas sitting on their table and another ripening on another stem. There was one year where there were no plants along that area and i thought they just went out and got a whole new giant banana cause i didn’t know how it worked. But most years i visit, i see the banana plant.
I’m here in Washington for good now so i can chronicle it throughout this winter. I used to live in SeaTac as well and i don’t ever remember it getting under 32 degrees where i was at except for maybe once every 3 years or so if i recall correctly.
It’s been there since roughly 2013? Fruited 3 times from my memory but some years i don’t visit at all. I was told it can only fruit every other year because 1 year isn’t long enough for it to grow. I’m just there more often now because she makes a lot of food for my daughter since I’m the only one from my generation on our side that’s having children. So instead of stopping by once every 6 months, I’m there almost every week now.
No one has any idea what variety it is anymore. They said they got it from a friend/ another banana grower somewhere in the family that lives in western Washington.
That sounds about right, there have been 2 or 3 years with mild winters in the last 12 years or so. It should be producing new pups every year, and those pups will fruit at the earliest in the second year (I’d usually expect it to take three years in our cool climate, though).
Since there are new pups forming every year, there should also be old pseudostems large enough to be fruiting every single year. Any year without a fruiting p-stem means that one of the previous two years was cold enough to kill the p-stems that year. The corm (underground bulb) would likely also be killed if it weren’t planted that close to the foundation of a heated building.
SeaTac (the airport) is the official weather station for Seattle, so they have very good weather records, and it has gone below 32°F in SeaTac every single year since records began. The low of 30°F in 1999 is the warmest minimum on record:
