The redesign is part of mayor Boris Johnson's £220m Great Outdoors programme to transform public spaces throughout the city.
Visiting the site with his brother, Orpington MP and leader of Bromley Council Jo Johnson, the mayor helped with the planting of two silver birch trees. He said of the project: "The high street now feels like a really nice place to spend time in, as well as shop, and I am confident that improvements like these will increase business for local traders as people are attracted to this impressive and transformed town centre."
Gristwood & Toms is also involved in tree planting in other London boroughs - Bexley, Brent, Bromley, Ealing, Enfield, Harrow, Sutton and Westminster - and has planted more than 1,000 trees as part of the mayor's scheme to plant 10,000 street trees across the capital by 2012.
Mark Lovejoy of Gristwood & Toms said: "Business is going very well. We are very busy and are recruiting a lot of staff. Our operations are out as far as Birmingham.
"A lot of our contracts are long-term and we rode the waves of the recession so that by the time the contracts were up, we were through it all."