My problem is to bring interest, from late July onwards, to the bank of my large natural pond.
The S facing bank of the pond slopes down at about 30 degrees from the lawn level to water which, depending on season is 4/6ft lower so the lowest two feet is usuall waterlogged in winter. Soil is VERY heavy clay with large flints chalky and hence alkaline.
From April to mid July I get good colour and interst from bulbs, marsh marigolds, solomons seal and candelabra primulas(that thrive particulalry well) and astilbes. The top of the bank can be very dry and supports dwarf blooms and the alpines in an artifcially constructed gravel garden, this upper level gets reasonable early morning and afternoon evening sun so gives low level close range interest for most of the growing season. However the lower levels are my bete noir from mid summer to autumn.
This bank of the pond is fringed by a heavy growth of flag irises and bull rushes that climb 9/10 ft from the lowest water level and hence at full height dominate and heavily shade the lower part of the slope.When the irises have bloomed and the primulas and astilbes have flowered the growth forms a very monotonous green wall especially when viewed from the house. Removing the irises and bullrushes would be a) very difficult and b) undesirable as they are a key part of the eco system of the pond for the newts, dragonflies and resident moorhens that thrive in it.
I have never suceeded in getting anything to give interest to this green desert in late summer/autumn. Countless lobelias have perished and hostas (which thrive on the gentler sloping N facing bank) rarely survive one winter.
I can of course prepare planting poskets but they are only little islands in a sea of impervious clay. Any suggestions most gratefully received.