Posted: 28/05/2014 at 09:16
My garden is the same, we have an underground stream so I'm told by neighbours which means any prolonged rain means getting the wellies out. Plants that can cope with this include arum lily, hosta, astilbe, geum rivale, actea simplex and dogwood. I have all these growing in my own garden. You can use annual bedding like cosmos for gaps as they won't have to survive winter and you can change your mind each year. I do lots of annuals and perennials from seed so if I lose them I haven't wasted lots of money. Lost a load of echinacea ''white swan'' this winter so I'm raising plants again which I will plant somewhere where I've raised the soil level. I've raised the level of one bed in full sun which has delphiniums, oriental poppies and gladioli in (I lift my gladioli in winter and repot in the green house in spring). Keep adding the mulch like you are doing and keep off the soil when it's wet to avoid compaction. I hope this helps!