Roses - how bad are they ?

Which is the best for the planet ?
Roses grown under the sun in Kenya then flown to the UK, or roses grown in a centrally-heated greenhouse in the Netherlands.
In the Porta Library there's a book called 'How bad are Bananas' which provides the carbon footprint of a whole range of objects, and it places a value on the carbon emissions of the two options.
This, however, is only part of the story - you also need to factor in other costs and benefits of the transport of roses across the world...

I look forward to reading the responses...