MediaCom knows a thing or two about how to turn words into action and get results. The media agency has employed conventional and unconventional thinking to ensure its environmental policy comes to life in the daily practices of staff. It encourages employees to walk or cycle to work once a week and to go on foot to meetings rather than take taxis. Keen for staff to think out of the box, it even allowed them to hire rickshaws last summer.

The latest venture is turning the company's central London office balconies into vegetable gardens, planting grow bags with tomatoes, chillies and pumpkins to show people how easy it is to grow their own vegetables. Staff are divided into teams and there will be a "best-looking tomato" contest at the end of summer. Mac Stephenson of the international department was picked to run the scheme because he has an allotment, and clients are responding to the venture, with MediaCom noticing that questions about sustainability starting to filter into tender documents, for example.

Inside the firm's two offices, every effort has been made to minimise the company's impact on the environment, from low-energy lightbulbs and sensor lighting to computers that go into hibernation mode after 20 minutes of non-use, to floor-by-floor recycling, which means that almost all the 627 staff know just where to put waste, earning the firm a positive green score of 91% in our employee survey.

Until recently staff were only able to recycle paper but new facilities means a wide range of other things can be salvaged from cans and plastic cups to empty toner cartridges and bottles.

MediaCom has already agreed a contract to use 100% renewable energy, is looking at means of generating its own electricity, and hires company vehicles from a carbon neutral car firm. Workers think the company is getting better at protecting the environment, earning it an impressive green score of 89% in our survey. They can see that MediaCom's environmental commitments are very serious (82%) and believe the firm's environmental impact is improving (83%).

The company has set a target of a 21% reduction in both water and energy consumption, and a 30% cut in waste, all between 2007 and 2010, and it has also set a target to reduce its CO2 emissions by 20% by next year. Its current offsetting programme includes planting 600 trees in Somercombe Wood in Devon and schemes to deliver solar lamps and ovens to communities in east Africa.

Environmental stuff doesn't stop staff getting on with their jobs (81%), chief executive Jane Ratcliffe and her team are open to suggestions for environmental improvements (75%), and don't drive around in fuel-inefficient cars while expecting staff to save the planet (77%).

Employees are aware of the firm's environmental policy and say that workplace signage is a constant reminder to think green (both 80%). However, they are a little hazy when it comes to knowing what ISO 14001 is, earning the firm a green score of just 25%.

There are showers and changing rooms for those who use two legs or two wheels to get to work (84%) and, as a result, most people don't travel to the office by car (90%, with just six firms scoring higher).