The Changing Face of Public Gardens

by Heather Prince

founded in 1868, is the nation’s only privately managed free zoo and one of the jewels of the Chicago lake front. It’s also a newly accredited arboretum and showcases a nationally accredited hardy hibiscus collection.

First and foremost, however, it is an oasis for animals of all kinds from endangered species to local wildlife. Landscaping such a place presents a unique set of opportunities and challenges. With 49 acres of grounds, including a 14-acre natural area, Lincoln Park Zoo provides a diverse array of outdoor experiences for around 3.6 million visitors in a typical year.

When landscaping zoo grounds, animal care is the central concern. Plants must be safe for the animals, so plant choices are screened by the animal care staff, veterinarians, and facilities to ensure they are not toxic or pose a hazard. “We often are challenged to find creative solutions,” commented Katrina Chipman, Director of Horticulture. “We do install plants inside habitats, and sometimes plants may not be as aesthetically pleasing because those habitats are created for animals and their speciesspecific needs. It may be something that the animal is going to eat or will use for enrichment. It may be something we are trying to establish inside the habitat to provide the animal with more privacy or shade.

For example, you may see pollarded trees — It’s not a practice that we’d normally advocate, but we do cut back some of our larger trees which keeps our animals safely inside their habitats.” The Zoo participates in the Association of Zoos & Aquariums North American Monarch SAFE (Saving Animals From Extinction) program by planting milkweed as larval host plants for the butterfly. But, because milkweed is toxic to many other animals, the staff restricts

its plantings to their natural areas away from zoo exhibits. They will be adding more to the existing collection of swamp, common, whorled and butterfly weed this year.

Once it’s decided to plant inside an animal habitat, it’s often a challenge once shovels hit the ground. Many of the habitats have a variety of top substrates used for animal health and welfare. “Soil can be a challenge. A lot of the soils that the animals need aren’t like the soil that we’d use in a nice, enriched garden bed,” observed Chipman. “For instance, the zebra area and giraffe yard is covered in crushed granite for their hoof health. We’re challenged to find a plant that will grow in that substrate. We planted a tree inside the red river hog habitat this past year and digging down into the soil we found years and years of built up sand and crushed granite. It’s definitely a challenge to know how well the plants are going to succeed with varying soil types.” In addition, certain species thrive with different substrates. “As regular habitat maintenance, the zoo’s facilities department in conjunction with our horticulture department will go in and loosen soils over time.” A part of the horticultural choices at the Zoo is working with the animal care staff to provide plant material as food and enrichment. The Zoo maintains a browse garden where plants and shrubs are grown strictly for animals’ diet. “Twice a week starting in June all the way through the time the plants go dormant, we will cut browse and deliver it to the animal areas,” said Chipman. “The majority is mulberry and willow, but we have a lot of other species as well. Hibiscus flowers are edible and will occasionally be used for browse. We won’t strip them of flowers, but we’ll give a few to the tortoises and sloths.” (continued on page 34)

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Finding a balance between how much can be cut back and have the plants still survive and thrive has been an ongoing challenge. “It’s been an ongoing conversation with the animal care staff on if we can grow enough for the animal enrichment or if plants can rebound before it’s needed again.” Mulberry is such a favorite for a wide variety of animals, that the Zoo has found an outside source to maintain supply. “In an exciting partnership with ComEd, they are able to drop off fresh mulberry from their routine utility line trimming that we clean and use all over the zoo, even freezing some to feed throughout the winter months.”

Beyond serving the needs of the animals, the Zoo is a large public park with a long history. Over time, the horticulture needs and expectations have evolved from a park-like setting of lawn and mature trees to more planted and landscaped areas. Nature Boardwalk was a big step in creating an ecologically focused natural area to showcase the plants of the Midwest and create a place for local wildlife to thrive. The design process began in 2008 and it was finished in 2010. “This really was an institutional shift for the zoo to further develop and diversify the gardens inside the gates,” commented Chipman. “This moment was where we moved from having monoculture grass areas with some nice trees to diversifying our gardens to create perennial beds, focus on pollinators, and add in wildlife-friendly plantings.” As the institutional expectations shifted, landscaping requirements evolved into a need for horticulture staff to come under the Zoo’s aegis instead of being contracted out. As the emphasis moved to providing for all animals, be they in zoo habitats or wild, it was decided to add more planting areas to provide for all. “In 2018 the horticulture department was restructured so that all wildlife – plant and animal care – were in the same department. As such, the horticulture team moved to a more science-based approach as well as working toward our arboretum status and accredited collections. It really has switched to having a real focus on plants and not making it an operational choice. It focuses on our actual plant choices and our installations,” said Chipman. This helped align horticulture into the mission-based programs at the Zoo and to build more garden spaces for local wildlife. “We’re very invested in the local wildlife and in migratory birds and pollinators and we’ve seen increases in these populations as our management practices evolved.”

Of course, planting for wildlife isn’t without its own set of challenges. “We have a healthy population of local wildlife. Wildlife also like to eat our plants,” observed Chipman. “There’s a threshold of knowing if the plants are going to survive. Do we test it this year and see if the echinacea are actually going to live without the rabbits eating every last one? Has the rabbit population decreased over time? (continued on page 36)

(continued from page 35) All those things come into play. It’s a little bit of a different mindset.” There are also limitations on what kinds of management can be done in the Zoo’s natural areas. Controlled burns are not allowed, for example. Perennials persist over the winter as long as they aren’t a hazard for visitors to promote insect populations overwintering in plant debris. Nature Boardwalk is selectively mown and debris allowed to remain as a way to limit invasive plants.

With this shift, the Zoo experience has also changed for its human visitors. “We’re not looking to replace everything. We’re trying to update as well as provide a more ornamental garden feel around our spaces and habitats. We’re focused on creating a diverse collection of plants that are going to be aesthetically pleasing for people to see and entirely immersive for the guest experience,” commented Chipman. One of the efforts to engage visitors is labeling all the plants. It’s a work in progress, but nearly all the plants are tagged. “We definitely see a lot of people stopping and taking pictures now, which wasn’t so obvious in the past. I feel like we’re really starting to meet the garden expectations of the visitors and even exceed them.”

Because space is one of the biggest limitations at the Zoo, plant collections are spread throughout the property instead of concentrated in a single area. You’ll find the 75-cultivar hibiscus collection planted in many different areas, for example. This also allows visitors to experience landscapes that can be repeated at home and offers wonderful spaces to gather ideas. “We’re striving to incorporate these living collections into our landscape beds,” commented Chipman. “Which I think is a benefit because people can see how to arrange them in a landscape and how they complement other plants and what other plants to combine them with. Just really see them in a garden setting instead of an open collection.”

As Lincoln Park Zoo continues to update and evolve its landscapes, Chipman hopes everyone will come out and experience them. “It’s a very diverse landscape! We’ve been focused on establishing our arboretum with new cultivars of trees as well as new cultivars of perennials and shrubs. We have a lot of things you may not see anywhere else. Also, our historical trees are definitely worth a visit. We have oaks here that are older than the city of Chicago. It’s really amazing to see something so majestic and old here in the Zoo. Of course, our 75-cultivar perennial hibiscus collection is amazing. Our large 14-acre natural area at Nature Boardwalk is something to see too. You’ll experience one of the best views in the city with downtown Chicago as the backdrop.”