I have a Cordyline and it looks lovely and adds some colour in winter, it is a dark purply red type colour
I love them Tracey.
Also have a New Zealand tough evergreen called astelia, which has bronze/purple sword shaped leaves, tinged with silver- lovely next to my narcissus at the moment!
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!
What about a mahonia for some winter yellow flowers? Also evergreen so will give some winter interest.
Jess, there's a lovely yellow cotinus also called "Golden Spirit".
I seem to have written an essay!
Most Winter: Mahonia's...Then Hammermalis Pallida or Arnold Promise(Witch Hazel) (Late Winter-Early Spring)... Then Corylopsis are flowering about now (March) Hazel (Corylus) Catkins now...Then... Forsythia... Then maybe Weigelia Middledorfiana (April-May) Then all summer long Yellow Potentilla's, Buddleja Globosa,
On the Herb Perrenial/Bulb front (flower):
Spring-Daffodils (vast number of varieties) Crocus (Yellow Mammoth is a good one!) Erythroinium Pagoda (dog tooth violet), Primroses common,oxslips and cowslips, Tulips
Summer-Geums, Irises, Potentillas, Vast range or Ligularia Britt Marie Crawforr has stunning dark foliage, another with good contrasting dark foliage is Lysamacia Firecracker or Alexandra (variegated foliage), Centaurea Macrocephala has great pinapple like flowers in summer, Creamy yellow: Leucanthemum Banana Cream, Various Hamerocallis (Day Lilly), Cephalaria gigantica (giant scaboius), Candelabra Primula's, Primula Florinda is brill, Euphorbi Polychroma & Palustris
Summer/Autumn Knifofia 'Bees Lemon', Solidago (Golden Rod), Helianthus (perennial varieties), Crocosmia 'Honey Angels' Thalictrum 'Flavum' contrasting blue leaves heads of yellow flowers) Euphorbia Skimmensis
Winter- Cornus (Dogwood) Flavermeria has yellow stems. Cornus Midwinter fire is maybe yellow/orange. Salix Britensis coppiced back (again prob more orange really)
Foliage- Grasses: Spring -Millium effuseum, bit later Deschampsia Tatra Gold
Spring foliage: Spirea's Firelight, Candlelight in spring, All year round Ilex Flavescans (Yellow new growth)
Berries: Sorbus and Malus (Rowan and Crab apple), cottoneaster
Climbers: Clematis Tangutica, Golden Hop,
Lizness - that's a fab list. Love Kniphofias and Crocosmias.
My absolute favourite is Hammamelis Mollis. It comes in orange and yellow but my absolute favourite is the yellow version. its winter flowering and also scented.
Agree with Verdun and others too much yellow it would be overkill. Best of luck with the border.
Potentilla fruiticosa has yellow flowers. Also Lonicera baggeson's gold has small yellow leaves and can be pruned to any shape if you wanted it could be topiarised and also the berries it has in autumn/winter are really vibrant purple nice colour that time of year. There are a good few varieties of Euonymus that are yellow in colour.
Good point Poddington - winter colour is so often neglected. Winter jasmine has bright yellow flowers on bare stems and looks lovely.
Keyser - that's wonderful! Didn't know that one. Sadly my garden is too packed with plants and too tiny for a cotinus - but one day.....
Lizness - brilliant list!
havadayoff - i have a wee yellow potentilla and it reminds me of yellow buttercups - so pretty.