Harvard’s Arnold Arboretum’s $30 million development plans for their Weld Hill site in Roslindale are rubbing many of the local residents against the grain.

The Arboretum plans to use 15 to 20 thousand square feet to house greenhouses and research laboratory space, 10 to 15 thousand square feet for their administrative buildings, a half-acre for new nursery beds, and space for 25 to 30 cars, according to its website.

However, residents of the area are not happy with the proposed plans, citing the “institutional creep” that they have experienced with other buildings in the area as a serious concern.

Wayne E. Beitler, president of the Longfellow Area Neighborhood Association, said that some land to the west of the Weld Hill plot had already been developed into a home for the elderly by the city.

“The city built a facility that was very modest, representing to the people that that would be the extent of it,” Beitler said. “But now the whole nine acres is this gigantic concrete building.”

He added that the city had justified the expansion by saying that the Weld Hill site next door would always be a “no-build zone.”

“There’s not very much green space left in Roslindale,” he said. “Our overall goal is preserving the majority of Weld Hill as permanently publicly accessible green space.”

Carter Wilkie, a Roslindale resident who is advising the Boston Redevelopment Authority Taskforce on the issue, said that the Weld Hill area is not zoned at present for institutional uses, but that once that is changed by the city it opens the door for almost unlimited future expansion.

“Once you let a complex through the door there’s no stopping it. It becomes a runaway freight train,” he said, noting the difficult balancing act the city must undertake to allow institutions to develop without overwhelming the neighborhood.

Robert E. Cook ’68, director of the Arboretum, said that the development was necessary for the Arboretum’s growth and that Weld Hill was one of the few sites they could use for it.

“The Arboretum needs to create modern research laboratories, which we do not have, if it’s to retain its scientific reputation,” he said. “This is the only parcel that the Arboretum owns that is not basically parkland.”

Cook mentioned the concessions that the Arboretum has agreed to make to the neighborhood in the past two years of negotiation over the site’s future.

“Harvard has proposed a portion upon which buildings can be built and a portion on which they cannot be built for 30 years,” he said.

The Arboretum web site also describes other safeguards against taking over the landscape too much, such as designing the landscape to reduce visibility to nearby homes. It also mentions measures to appease residents that include making the site more accessible to them by constructing pedestrian trails and improving site maintenance.

But Beitler said the measures are merely “a series of window-dressings.”

“We recognize that [the development is necessary for the Arboretum] and would like to support it, “ he said. “But we cannot do that without any guards against future expansions.”

“On the surface it sounds ok,” he said about the 30-year embargo on development. “But what’s the funding cycle for institutions like this? About 30 years.”

Cook disagreed.

“It’s very hard to predict,” he said. “Thirty years is a long time from now.

“Let me put it this way, I won’t be director.”

—Staff writer Alexandra C. Bell can be reached at acbell@fas.harvard.edu.