Tending to a communal garden for 15 years takes a lot of time, sweat and money.

Just ask Des Plaines residents Irma Lehmann and Peggy Losik, who had been planting native flowers and bushes along a 40-yard stretch of their Mill Run condominium complex's eastern property line.

That's until this spring when the two elderly women realized their actions to improve their surroundings constituted encroachment of what is actually Cook County Forest Preserve District land.

"Every day we are looking for a summons in our mailbox," said Losik, a registered nurse.

Where once invasive plants such as poison ivy and garlic mustard crept, the women helped cultivate native species such as coneflowers, wild phlox, black-eyed Susan, and joe-pye weed. They replaced the harsh soil with plant friendly dirt and added mulch.

"I think the forest preserve should be very happy with that," said Lehmann, who is retired. "We cleaned out the poison ivy. We hope we can keep going to maintain the garden."

Losik said once the land was cleared many of the native plants came up on their own. "Before we started this, we had no birds or butterflies," she added.

Initially, the women began planting along the edge of the complex parking lot and moved further inward after major flooding in 2008 swelled the Des Plaines River, engulfing a ravine-like area just east of their stretch of garden.

The women also cleaned up debris after the flooding and rid the area of discarded tires and trash.

"They (the forest preserve) were never going to come or do anything about this so why couldn't we clean it up," Losik said. "It was never from day one clear to us where our property ends and theirs began. Sometimes in the summer, the weeds would be as tall as me - five foot, one inch."

Yet, a complaint from a neighbor to the county has effectively put an end to their gardening activities, said Cook County Forest Preserve District Spokesman Steve Mayberry.

The women won't be cited for violating forest preserve rules, he said, nor will they have to pay a fine. But they will have to cease all gardening operations.

"We can't allow them to keep doing this," Mayberry said. "You cannot encroach on forest preserve land. We can't say it's OK in one place and somehow not OK in others. We are simply enforcing the ordinances, and have been thoughtful about how we approach this."

In the grand scheme of things, what these women did, though a violation of forest preserve district policies, was not egregious.

"If what you want to do is to keep an area clean," he said, "that is something that we will work with you. We honestly believe they thought they were doing the right thing. We would love to see them join our Preserve Keepers Corps."

The volunteer corps is the umbrella group under which more than 9,000 forest preserve volunteers perform a variety of activities, he said.

As for the existing plants in the garden, they can stay as long as they are native, Mayberry said.

"It would be left as is," he said.

Forest preserve district staff will be surveying the area to determine what's native and what's not, he added.

"It's incumbent upon us to make sure that there's no new nonnative species being introduced," Mayberry said.

So far, no one from the forest preserve district has contacted the women personally about quitting their gardening. "We just decided that we probably better wait," Losik said. "It was never our intention to harm anything. We would like to be able to continue what we're doing."