Winning sites included Hatton Hill Park in Sefton, Ilford War Memorial in Redbridge, London, Castle Hill Newhaven Local Nature Reserve, Southport Botanic Gardens and Baggeridge Country Park in south Staffordshire.
Chief executive officer Nick Temple-Heald said: "Pressure on local authorities’ budgets has never been greater but the public still need to have beautiful green spaces. Efficiency and working together has never been more important to achieve and maintain high standards.
"We work hard to ensure we provide the right people, the right resources and the right attitude to help our clients and communities succeed. This year’s poor weather conditions have proved a challenge operationally and aesthetically.
"It has required our teams to rethink strategies to keep the parks and gardens looking their best but I’m thrilled that we have succeeded against these odds and can proudly display 36 Green Flags."
He added that judges applied stringent standards on maintenance, insisting green spaces are weed and litter free, clean and safely maintained. Achieving Green Flag status required a strong and on-going partnership between local authorities, communities, businesses and contractors, Temple-Heald said.
The Landscape Group cares for parks and gardens, amenity green spaces, woodlands, beaches and nature reserves. Fine-turf specialists meanwhile look after bowling greens, golf courses and cricket squares.
As well as grounds upkeep, the group, which won six BALI awards last year, has built award-winning landscapes including the modern Media City piazza in Salford.
The Group has a variety of term contract. Some, like Coventry are busy city-centre ‘clean and green’ operations. Others, like the Lee Valley Regional Park, encompass a number of wildlife and conservation havens and nine Green Flag parks.
Landscape Group is one the largest amenity horticulture specialists in the UK, with an annual turnover of £50m and more than 1,000 staff. It is also one of the longest established, dating back to 1919.