Pigeon problem in balcony garden

we had the same prob. Finally we had to get iron grills to cover entire open space of balcony thus preventing the pigeons invasion. We are now living in peace without pigeon's **** decorating the balcony daily.

 

Nets would be the best choice in that case.
Inexpensive methods that you can use is take a plain black cloth [old tshirt or dupatta or any cloth but plain black cloth], tie it on a big stick [use a wooden stick or old floor mop stick] and place this stick in balcony such that air blows and cause movig of the black cloth. this will discourage pigeons to stay in the balcony.

But pigeons are very clever and once they understand our tick, they'll not be afraid.

Putting nets will be the best option as per me if you want fool proof method.

 

Even we have pigeons who come to eat small spinach plants and other plant leaves kept in the balcony. We don't scare them away. Let them eat... I sometimes keep water for them also.