They will also remove old shrubs near terminal 4 and replace them with ivy and turf to open up the area.
Other jobs will include infilling hedgerows and creating new planters with seasonal bedding for terminals 3 and 4. OCS will use more than 19,000 ivy plants, over 1,500 beech hedge plants and around 4,000 lonicera plants.
More than 2,000m2 of turf will go down while every plant that is removed will be recycled at Heathrow’s recycling site and turned into compost to be used within the airport perimeter. The three-month project will end in February.
"The 17-staff team was also responsible last year for creating floral Olympic rings, the Paralympic Agitos symbol and union jacks at Heathrow during the Olympic Games," said a spokeswoman.
"We were recognised for our work by winning the team-of-the-year award at the annual OCS Heathrow awards," she said.
OCS Group employs more than 77,000 people in 40 countries, with a turnover in excess of £710m. More than 70 services include horticulture, catering, cleaning, waste management and security.