The 12 December is the anniversary of the death in 1851 of Joel Poinsett, who introduced the plant from Mexico to the US in 1836.
The designers have fashioned the ombré gown from 300 stems of red, variegated and cream poinsettia.
Okishima & Simmonds's Jessica Simmonds said: "We love to create unique designs that merge the floral world with the fashion world and International Poinsettia Day has given us an exciting opportunity to do that.
"We wanted the dress to flow so that it looked as though it was growing out of the poinsettia beds beneath, so used the traditional red poinsettia for the skirt and showcased other colours through the bodice."
In 2014, eight million poinsettia plants were sold in the UK in just two months, an increase of 15 per cent on the previous year. The poinsettia fashion shoot was set in the poinsettia glasshouse of Hill Brothers Nurseries in Chichester, whuch grows 500,000 poinsettia a year.