I don't imagine weeds would be too much of a problem really. Like you say, if you are buying in all your browing medium then that's a weed free environment to begin with. Like you say, you are out of the way of most of the seed spreading; birds I suppose will leave seeds in their droppings . . . dandelions and other very light airborne seeds may turn up. I reckon weeds will not be much of a problem at all.

Probably lots of other problems no, challenges, to deal with though!

The people next door to me brought the weeds to my pots. The worst is the clover that keeps popping up everywhere. :(

As long as the wind blows & the birds fly... there's no escaping weeds.

LOL!

Had a full balcony deck last year...hanging plants, plants hung over the side, plants growing in containers on the walls of the building. May have had a weed or two, but by far the bigger problems were (1) torrential rains (2) excessively high heat from the heat pump on the balcony (3)keeping up with the rapid dehydration on hot dry days. Weeds were the very least of my issues !

When I first started balcony gardening, I was stunned to find weeds and all types of pests. Nobody around me gardens, and I haven't had much luck attracting birds, and I am surrounded by concrete and glass. Nonetheless, I built it, so they came (the weeds and pests, not the birds). Unless you are sure your growing medium is sterile and you grow everything from seed, you bring 'stuff' to your balcony with everything you buy to put out there.

It isn't an overwhelming problem, I don't end up doing a lot of weeding. Just didn't want anybody to think that balcony gardening is problem-free :-)>