Posted: 06/03/2014 at 16:41
I'd agree with nut - it can be a very harsh colour so you need other things to stop it jarring. I use some of the yellowy Loniceras (shrubby honeysuckle) as an evergreen foil for other planting and use creams, whites and softer shades of yellow to stop the brighter ones becoming too overpowering. The paler Potentillas that Verd mentions are very useful and easy to source and maintain. Lots of spring bulbs in softer shades are great for that too. You could also go in the other direction and introduce a few rusty orange colours as they can be more subtle. The Ligularias have an orangey tone to the flowers, and some of the Red Hot Pokers (Kniphofia) have rust coloured flower heads. Irises are available in virtually every shade if you like them. If you like grasses, there are bronze forms of Carex which give a nice contrast to brighter planting.
If you don't want to use a completely different colour like blue or purple to get a balance, use the greatest shade of all in the garden - green. Goes with everything!