Thanks for advice folks, we've glued, taped, used sealant, even pond sealant to no avail. One of the problem is finding the hole as it is so small, so you need the water to find the hole, then mark it, then empty and dry. Done all that bit now. My preferred method would be the both but it has previously failed, and Mr gw is pretty handy ( unlike me, I'd be clueless but he's a proper problem solver). We will perservere ( well he will whilst I watch! ). I'm delighted my last year's osteospermums are in flower, they don't usually survive from year to year but it's been so mild this year. Now where did that daisy thread go?