I have recently seen a gorgeous and very modern twisted vine with tendrils going off at different angles which I think would look great on my balcony. Is this a reasonable idea or may it grow out of control?
Did you see this vine (vitis vinifera) in a garden centre?
Ask them where it is from - France? Italy? If imported from the latter - has it been acclimatized?
The vine can do well on a sunny well exposed Paris terrace. If you go to Montmartre you will see a well establised vineyard which proves that the 'vitacea' family tolerates the climate here. You will need more advice on fertilising and pruning to maintain your 'pied de vigne' correctly.
Yes you can. But again be sure whether it has been acclimatized beforehand. Olive trees imported directly from the south of Italy have not been through this process and will be particularly vunerable to a hard frost. If you don't know - protect it will a 'toile de hivernage'. Ensure that the pot is slightly raised - this will ensure proper drainage as well as protecting the pot from frostbite!