Hi Calin,
I see you are in zone 6, this means that you can't grow much bananas outside.
musa basjoo will survive (the corm) but I think its impossible to grow other species outside. maybe you can try musa velutina(like mskitty said), sikkemensis or a musella lasiocarpa.
for dwarf ones in pot you can use musa zebrina, or just the musas that you can buy at your shop/gardencentre.
for which species are you looking? maybe i can find a site which ships to romania.
on this site they sell basjoo, basjoo 'Sakhalin' (larger and growing faster) musa sikkemensis and musella.
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