I wanted to share with you the results of this experiment, because for ages i have been searching exact data on cold hardiness of bananas, and while the general elements are well know (this
is hardier than that
) when it comes do to put down exact values, i did find hard to get a precise picture on how hardy a banana could be.
To do this experiment i choose a dwarf namwah; while it may not be the hardiest among all
, it is still a very vigorous plant, people tell me it also fairly productive, I personally noticed that is very resistant to several stresses, and it is, in my opinion, the best subject, overall, for someone willing to grow bananas in a zone where bananas aren't meant to grow.
Before this experiment my method of growing bananas has been this one: i planted my bananas in ground on 1st of April (I think the neighbors thought about a joke the first year i attempted this) and potted them up at September. I did this for several years, and i did get several pup in the process; some of them have been kept for testing purpose.
Once i managed to get a pup big enough, i did grow it to a decent size (5') just to attempt this experiment and I did plant it in ground hoping to overwinter i: following some suggestion on bananas.org, i did plant it fairly deep.
During all the summer i attempted to push it at the best of my possibilities, hoping that the sheer size of it could help to offset any physiological problem due the nigh level of nutrients.
This was the plant in April 2015, and next the plant in October:
Long story short, the plant arrived in perfect condition to the end of November, where we got out first cold damage: at the relatively high temperature of 3°C (that is 37F) the plant started to show some damage:
But overall the plant held very very well for all the winter; pretty much at Christmas it was still in a good overall shape:
When you get a winter so warm, you can't avoid to be happy for your plants, but, in the meantime, you are well aware that no new knowledge is being made; it wasn't surprising to see a Dwarf namwah doing well with temps regularly above the zero/32F.
Luckily, i January we got something that was normal till few years ago, but right now looks pretty unusual: a cold spell.
At first it started slowly: on the night between 16 and 17 January we got -2,4°C (27,6F):
The following night we went to -3,7°C (25,3) with ice starting to form in water left outside:
On the 20th the temperature reached -6,1°C (that is 21F) with extended damage on the entire plant/pseudostems:
You can see the "washed away look of the tissue cooked by the low temperatures:
The next day the temperature reached the absolute minimum at -6,4°C (that is 20,5°F).
As you can see from this graph, we got an extended period of time (about ten days) with night dripping regularly in the low 20s;
During all this time the plant never had any other protection than the one due the planting location. I wrapped it in frost cloth at the end of the frost spell - the reason was that i feared new cold spell but we didn't get any. Admittedly, i didn't planned to get so much cold for my experiments: so i wasn't really prepared but on the other had, i also think that if you wanna grow something outside its zone, you've got to choose what is worth an extra mile (in my case, mango) and what isn't (bananas); i like bananas, but i can't give to all my plant the lever of care i give to my mango, so they had to deal with difficulties themselves: on a multi.year perspective, this is the only way i can hope to grow plant in a sustainable way.
Well, at this point you have seen what the have been trough. They are dead right? RIGHT?
Few days ago they showed unequivocally that they are sill growing: so, except the damage to the most exposed leaf sheets, they didn't even lose the pseudostem. The picture is already old and the smallest plant has almost finished to unfurl its first leaf.
This may not be a surprise for some of the most expert zone pusher out there, but for me it was quite a surprise.
So i think that a couple of thing can be said from this small experience i have done; Dwarf Namwah can be a interesting banana to grow for beginners and zone pushers, and they can survive pretty well to temperature in the low twenties.
I hope this may help someone undecided on what bananas may do well in its place.
I'm well aware that a surviving bananas is pretty different from a fruting bananas, but the latter can't be achieved without the former, and dwarf namwah seems the best bet in my opinion.
(For the record: dwarf orinoco did better than dwarf namwah in cold environment, but is slow and not very vigorous, and i have an hard time convincing it to grow. And fruits at my place apparently take forever to ripen.)