Horticulturists, parks managers and other landscape-related professionals could soon be able to join the Landscape Institute as non-chartered members.
At the institute's EGM on 14 July, members voted to change the way in which the 85-year-old organisation is governed. Institute president Noel Farrer said the vote is "a mandate for modernisation and future success".
He added: "It allows us to reach out and encompass the needs of a widening group of professionals involved with the landscape and to give us a more powerful voice to influence decision makers."
Over the past 25 years landscape, and the environment, has been recognised as a "massive" issue that encompasses much more than landscape architecture and engineering, said Farrer. "If the Landscape Institute wants to meet its aims and follow best practice in the art and science of managing the landscape, then we have to embrace a broader church.
"There are movers and shakers out there who have done a lifetime's work in landscape, perhaps as the head of a national park or an area of outstanding national beauty, or they might be the head of parks in the London Borough of Westminster - and there's no professional body or specific forum representing those people. We need to recognise their expertise."
Chartered membership will still be exclusive to qualified landscape architects though, he explained.
"This form of membership is not about watering down our principles or standards but starting to think about joining our voice with others. We have a huge common interest with other voices such as horticulture, ecology and green infrastructure."
Over the next three-to-six months the institute will create detailed proposals on how the motions will be carried out. As the institute is a royal chartered organisation, the privy council must agree to the changes before they can be incorporated into a revised charter, on which members will vote.