The Pennsylvania Horticultural Society has launched a tree-planting program with an ambitious goal: 1 million trees throughout the tri-state region.

Spread over 13 counties in South Jersey, Southeastern Pennsylvania and Northern Delaware, the ambitious urban forestry effort will put tools and resources in the hands of individuals, community groups and corporations who will do the labor.

The city of Philadelphia's "green" promise to plant 300,000 trees is included in the million-tree number.

The project--called Plant One Million--will get some help from new software developed by the U.S. Forest Service.

It's called iTree, and it works like tax software. Plug in data such as location, maximum height and average rainfall. Then input what you want the tree to accomplish: create shade, block wind, and/or absorb storm water. The software then spits out a list of trees that would be appropriate.

While most people intuitively appreciate the aesthetic and health benefits of trees, iTree can express the benefit of trees in dollar amounts. For example, a homeowner can expect a 20-foot red oak tree to save him $116 a year in energy costs.

"It helps to quantify these benefits when city planners are looking at where to make investments," said U.S. Forest Service Chief Tom Tidwell. "It's an ideal tool to quantify benefits--you can have good numbers."

The free, online program can also be used to track where trees have been planted--very handy when you're planting a million trees.

"It creates opportunity for citizens to self-quantify their plantings, and become part of the active force of folks out there who are counting trees as they plant them," said PHS vice president of programming Maitreyi Roy. "One of the aspects of Plant One Million is to plant the trees, [and] definitely count them."

Considering Philadelphia's climate and urban infrastructure, iTree has calculated that an appropriate tree canopy would cover 30 percent of the city. Tidwell admits that is a lofty goal--but not impossible.