Love is in the air as red rose sales soared for Valentine's Day in Thailand.

The colourful blooms are seeing rising demand at the Suan Kularb Suay flower shop in Khon Kaen province on February 13, just before the anticipated Day of Hearts.

Shopkeeper Suphaporn Thanasarndamrongkul, 48, is earning a handsome income as she rolled out a 'buy five, get one free' promotion for customers who buy flowers as a couple.

For those yet to find their better half, she offered a 'buy 10, get one free' deal instead.

Suphaporn said: 'Customers usually buy the roses as shrubs. They could grow for up to 30 years if well-maintained. Roses are a favourite since they are easy to grow and cheap.'

Each shrub sells for between 150 to 4,000 THB (around 4.4 USD to 120 USD), depending on the variety and size.