posted 1 month ago
My experience with grapes is that they love to put on huge amounts of growth every year. I suspect they will try to swallow your balcony, and move on to the neighbors if you give them half a chance!
From the prospective of shade and privacy in the summer, which then dies back to give you winter light and warmth, it sounds like a great idea.
From the prospective of keeping the plant happy, I suspect you're going to want the largest pot/planter you can, and ideally have some sort of small reservoir at the bottom to help even out the water needs. Being on a balcony, you can easily use wash-water to water it, along with a little fertilizer P. (Just makes sure you're using a plant-friendly soap.)
My "beside the front porch" grape vine rooted a stem that ended up on the ground. I popped it in an approximately 4 liter pot while I decided if I knew anyone who might want it. It doesn't have a decent reservoir, and dropped most of its leaves with the first heatwave. It's still alive, and I'm making sure I keep a close eye on the soil.
However, both this plant, and a different variety I started from a cutting, have both convinced me that to do well, they need a decent amount of soil and space for the roots. If you can do that, it likely will survive. Grapes start fairly well from cuttings, and they need regular pruning, so if you know anyone growing one, I'd suggest you start with a cutting and see how it goes. I personally, would hesitate to spend much money buying a potted grape vine for this application - this is a bit high risk! I don't suppose you can plant it in the ground and grow it up the building until it gets to your balcony? I've seen pictures of vining plants being used to vertical garden that way.