water logged bed

I have a triangular bed which is only about three years old.  It has heavy clay soil like the rest of the garden, but because it is still 'young' has not had so much stuff worked into it.  It gets totally water logged in the winter and like concrete in the summer - true clay soil.  Last year I planted a selection of Heucheras, lots of bulbs, Astrantia and seed from Verbena.  There was also a Knautia there already and small Bergenia which seems to survive. 

After this winter the Heucheras seem to have died, I am assuming the bed was too wet for them in the winter, as when I dug down about four inches last week the water just filled up the hole! The Verbenas did well, so did the bulbs, even Nerines. 

So two questions please.   First will the Heucheras do better in a bed that gets sun virtually all day, and can I move them now, assuming I can rescue any of them?   ]

Second question, any suggestions as to what I can put in this bed which gets sun for part of the time in the summer, none in the winter and will, I know, need some grits etc worked in. It follows on from the patio so nothing that will obstruct the view too much.  One thought I have had is could I put ferns, grasses and hostas in this bed.   

I would really appreciate some advice and help, as it is so frustrating to lose so many plants. 

Thanks for reading this far....