yea, this has been brought up a lot. the way that i do it is to use toothpicks to hold them in. Not through the plant, but a few on either side to make a solid support for it. the toothpicks will blend in to the cork better than silicone or wire and they eventually will breakdown after the plant roots. another method that a lot of people use is to drill 2 holes to either side of the brom and thread fishing line around to hold it up. i havent used that method, because i can always see the line =) but it makes for a solid hold and you can clip it away after it roots enough to hold itself