Petaluma’s eco-smart food forest offers bounty for all

To the eye accustomed to public buildings surrounded by nondescript, neatly trimmed lawns, the landscape of Petaluma’s Cavanagh Recreation Center looks unruly. In some spots you can barely see the building behind thick layers of plants, trees and vines.

Despite appearances, the building is not abandoned, nor is the landscape untended. It looks exactly as it should — with a thick “forest” filled with food anyone can forage, for free.

In the 14 years since it was installed by volunteers for Daily Acts, a Petaluma nonprofit engaged in community education and projects to foster sustainable living practices, it has become a model for landscapes that not only don’t harm the environment, but give back.

Trathen Heckman, founder and director of Daily Acts, said a food forest is an intentional set of plantings that mimic a natural forest system. Rather than having multiples of the same plant, all with the same sunlight, root and nutrient needs, a food forest has layers of plants — trees, ground covers, roots, shrubs and herbs — all with different needs that nonetheless comprise a healthy ecosystem.

“If you think about a natural forest system, a forest ecology, there are ground-level plants, small plants and midrange plants, and there are upper-canopy trees and vining layers,” Heckman said an a recent visit to the forest garden. The garden happens to be right across the street from his West Petaluma cottage, where the landscape also holds a variety of edible and beneficial plants.

“In a food forest, there are up to seven or eight structural layers,” with different needs, he said, pointing out a slice of the landscape where comfrey thrives beneath a bank of elderberries, both of which are medicinal plants. ”So instead of one thing, you can have three or four or up to seven plants working together in a community, with different needs, that contribute different things.“

Saving rainwater

Partnering with the city of Petaluma, Rebuilding Together and Petaluma Bounty, which maintains a community farm, more than 230 volunteers pitched in over the course of a weekend in 2009 to sheet mulch to transform 3,000 square feet of turf into the beginnings of a “forest” of more than 100 food, medicinal and habitat plants. They dug swales and rain gardens into the ground to retain rainfall to recharge the groundwater rather than allow it to run off into the gutters and wind up in the Petaluma River.

“If you look at all this concrete, what happens when it rains is it runs off, goes into the Petaluma River, and it takes all the oil and contaminants,” Heckman said. “We’re dehydrating the Earth with all of our buildings and our structures. When you allow (the water) to sink into the ground, it recharges the groundwater and it feeds the root of plants.”

The volunteers also installed drip irrigation to efficiently deliver water only where and when it is needed, to around 110 plants and 30 fruit trees.

Daily Acts figures the garden uses only 20% as much water as the lawn, saving 65,000 gallons of water per year while also providing many pounds of food throughout the year that anyone can come by and pick. No appointment or permission is required. At the same time, the city, which owns the building, does not need to spend money on pesticides, herbicides and lawn-mower fuel and maintenance.

Daily Acts also installed rainwater catchment tanks that divert rain captured in the roof gutters for use later in the dry season. At Cavanagh, there is one 1,400-gallon and 10 50-gallon tanks that irrigate on a gravity-fed system.

Over the years, Daily Acts has installed 37 demonstrations gardens around Sonoma County. Not all are food forests, but many have food elements, including a public garden at the Petaluma Library.

“If you go to the library, it’s raining down mulberries. There’s a 20-foot-tall mulberry tree and all kinds of plants,” said Ava Castro, programs coordinator for Daily Acts.

Heckman added, “It takes awhile for people to understand this is free food. It’s an educational thing. But over time, a lot of people come and harvest it now. It’s the same with the City Hall and library gardens we’ve installed.”

Edible forest

Spencer Sutton was a young volunteer that weekend in 2009. The experience was inspiring and set him on a career path creating ecological and sustainable landscapes with food-forest features such as mostly native and drought-tolerant plants and rainwater and gray-water catchment systems. He said over the intervening years he has seen public tastes slowly shift to accept a new aesthetic in landscaping that is not just decorative.

“I pass by it (the food forest) almost every day and integrate with it often,” he said. “I’ve been harvesting elderberries for medicine. The figs are always a big favorite. The way it’s grown is the most inspiring thing to see.”

One of the important design principles, he said, is to create landscapes based on available water that don’t need to rely on municipal supplies.

A typical food forest, he said, would include plant “guilds” planted around a nut or fruit tree. Ground covers at the bottom layer might include creeping thyme or oregano. The canopy layer would be the tree, with descending layers, each serving some niche with useful or edible plants. Beneath tree branches may be kiwi or passionfruit, with shrubs such as pomegranates or apple guavas in another layer, Sutton said.

“With these gardens, not all of the plants would be food-producing. Some (like salvias or milkweed) would attract beneficial insects. It’s focusing more on polyculture than monoculture.”

With many people talking about carbon neutrality as a goal, Daily Acts, employing new technology developed by Santa Rosa landscape designer Rick Taylor, has discovered the Cavanagh Center food forest actually sequesters more carbon than was used to create it or maintain it.

Taylor’s Sandbox Software created a digital carbon calculator, which determined that the old turf landscape at the community center drew down 154 tons of carbon per year from the atmosphere, where it was contributing to global warming. The new biodiverse landscape sequesters 2,106 tons of carbon per year and puts it to positive use for plant life.

The new tool can give information to measure sustainability at the front end of a design project.

“It will calculate the carbon footprint of a landscape down to the smallest component of the landscape and will tell you how long it will take your landscape to sequester the carbon it took to create it,” Taylor said.

It still takes a community to maintain the food forest, so Daily Acts holds work days that include trimming and weeding but also are a chance to learn about the garden and how it all works.

“It’s really a great way to connect with the community and teach the community about this garden and about how you can really take these practices and implement them at your own homes,” Castro said. “We want to shift the paradigm about how we think about water, about sinking water. So these work days are a really beautiful way to teach, and people in the community also bring their own knowledge to share.”

The next maintenance day is Aug. 18. The group will host an in-depth tour of the garden and its sustainable design features Sept. 21.

Castro said Daily Acts on Aug. 15 will debut new pages on its website focusing on its demonstration gardens, including the Cavanagh food forest, the plants growing there and a harvest schedule so people can know when food is ready to pick.

You can reach Staff Writer Meg McConahey at 707-521-5204 or meg.mcconahey@pressdemocrat.com.