Dahlias can be found in variouis shades of red from bright orangey scarlet to deepest crimson and almost black. There are also white versions and red with white tips to the petals.
To get the best choice you need to google about for a dahlia specialist and order plants now for growing on from the spring. You'll also find them being sold in sachets in garden centres any time now.
The tubers need to be planted in good compost and kept shelterd from frosts before planting oudoors in the ground or in pots from early or mid may depending on where you are. If you're clever, you can start them early and take cuttings from the new shoots and thus get more plants for your money.
You can check out seed suppliers such as Thompson and Morgan or Chilterns for flowers in your colour scheme. You could also simply use black ceramic vases or pots to hold red and white flowers for the reception.
