Posted: 15/07/2016 at 17:59
I think the geums might find it a bit damp but if there's enough sun and you add some grit and compost when planting, they'd be an excellent choice.
Don't know how big the area is, but good old Potentilla (an orange variety) would give you a long flowering period and will be a good backdrop for other things. Some of the dogwoods would give stem colour in winter if you have room.
Many Ligularias have good orangey flowers and like a bit of dampness. They do like a little bit of sun though.
Don't forget bulbs too - if the soil's a bit too moist, you can sink a few pots of tulips into the ground. Loads of good oranges. The early species ones would be ok and there are lots of orange varieties of those.
You'd just have to check if they're ok with alkaline soil though - I've never had anything but neutral to acid soil. The potentilla would certainly be fine.