Iris for bog garden
 

Due to being so busy this winter I neglected to split and plant a bucket of irises I was given last autumn. I have now cleaned an split these and am suprised to see they are still in one piece. The bog garden (an old plastic sink sunk into the ground with an overflow from a tiny pond trickling into it) will be filled in this week.
I have read however that irises like a bit more drainage than I anticipated. If I make sure the plug hole in the bottom of the plastic sink is kept free to drain, will it be enough for irises, or should I plant them elsewhere and consider another plant instead. Or is it necessary to maybe drill more holes into the bottom of the sink?
I am expecting no blooms this year,so won't be suprised if they grow blind.
Thanx G