Posted: 12/07/2015 at 09:32
Evelyn..........are you thinking of adding perlite just because you read it was a good idea or are your plants actually suffering ?
If the latter, you will need to remove your plants from their container and mix the perlite thoroughly with whatever compost you choose to use. Just to add perlite on top or making small holes to pour it in will be a complete waste of time and effort.
If it really is impossible to remove the plants, the other option would be to dismantle your planter or break it - depending on the construction - and start again. Hope you manage to resolve your problem one way or another