Maps that are rich in detail help us communicate the complexity and evolution of our dynamic garden.

Lurie Garden is intended to be an ever-changing, dynamic planting. The evolving relationships between plant groups and their role in the overall design requires constant monitoring as well as deep historical and horticultural knowledge unique to this place.

Documenting these intricate relationships is challenging, and requires unconventional approaches. As we work toward a viable system, along with learning about our limitations, we’ve gained meaningful insights into how to guide the garden toward a vision of a more beautiful and ecologically rich oasis in the city.

The garden was originally created as a collaboration between the landscape architecture firm Gustafson Guthrie Nichol (GGN) and garden designer, Piet Oudolf. GGN envisioned a strong, detail-rich structural framework, steeped in history and imbued with a powerful sense of place. In their words, their role is to “express hidden histories and repair connections in the landscape.”

An early GGN concept plan of Lurie Garden. Credit: Gustafson Guthrie Nichol.

Piet Oudolf designed a four-season tapestry of color and texture to overlay that structure, choosing plants that worked well together on the site physically and aesthetically to draw out the feelings you might encounter in nature. Indeed, he has said that creating a garden is all about emotion; using rhythm, repetition, form, and color to evoke the spirit of nature in a controlled way. GGN and Oudolf’s ideas came together to bring this corner of Millennium Park to life, making a garden that is rich in detail and meaning and rewards every visit with something new.

Lurie Garden plant combinations are especially lively in early summer.

The plant combinations that Oudolf creates ebb and flow, growing together over the seasons as plants emerge, mature, and die off at different rates. For example, near the southeast corner of the garden is a cluster of goatsbeard ‘Horatio’ (Aruncus ‘Horatio’), which matures to sturdy, 3-foot shrub-like mounds by early summer. But unlike a true shrub, it dies back to the ground in winter, so in early spring there is significant empty space in that area while we await its lush greenery.

Goatsbeard ‘Horatio’ (Aruncus ‘Horatio’), with mature, 3-foot shrub-like mounds in June.

Instead of leaving bare ground between these clumps where weeds might germinate early in the season, Oudolf planted a spring ephemeral called Virginia bluebells (Mertensia virginica). Virginia bluebells come up in mid-March with large leaves that cover the ground and keep weeds from sprouting. The bluebells flower in April with beautiful blue and purple blooms. As the goatsbeard finally start to fill out in May and then bloom in June, the bluebells die back to the ground and go dormant. These two plants are a perfect match: growing in one spot, the bluebells suppress spring weeds and give welcome color and pollen early in the year (they’re a bumblebee magnet in April!), then the goatsbeard takes over with lush green growth to hide the withering brown leaves of the bluebells.

Goatsbeard ‘Horatio’ and Virginia bluebells in April. The bluebells flower in April with beautiful blue and purple blooms. As the goatsbeard finally starts to fill out in May and then bloom in June, the bluebells die back to the ground and go dormant.

The garden was designed to change over the years. And change it does! Over the course of the year we watch on both a micro and macro level to see what direction the planting is going in, and then, often with Oudolf’s input, make edits in order to ensure that the garden continues to tell the story that it was designed to tell, with ongoing updates that reflect our maturing vision.

Lurie Garden horticultural team and designers discuss garden updates to an area of hosta that had gotten too big. From left to right: Shannon Nichol of GGN, Yaritza Guillen, Peter Slothower, Laura Ekasetya, and Piet Oudolf.

The ability to make informed editing choices in the garden presupposes a clear understanding of plant dynamics in the garden. When deciding whether to alter a species’ footprint in a combination, allow it to spread, or to remove it entirely, it is important to know how the plants interact with their companions while in bloom, over the seasons, and how their relationship has changed over the years.

One case of an editing decision that followed this process was with this clump of threadleaf bluestar (Amsonia hubrichtii) that came to dominate the middle of the light plate after over a decade of slow and steady growth. In order to keep it interesting and dynamic, Piet suggested we remove a section in the middle of the cluster. Now, what looks like a single large cloud of foliage from many angles, has a break to show the plants behind it when viewed just right.

For example, there is a section of the dark plate with a large mass of hosta ‘Halcyon’ (Hosta ‘Halcyon’). Over the years, this patch has slowly spread until it became a flat mass of foliage making a dull intrusion in its visually complex surroundings. By the Fall of 2018, it became obvious that there was too much of that single plant. Without knowing the history, we might have thought that the hosta was too aggressive and decided to take it out altogether. We also could have made other choices that might have repeated previous combinations that didn’t work. But Oudolf revealed that the original intention with that area was for the hosta to offer a small seasonal spot of calm for the eye between more finely textured companion plants.

A large mass of hosta ‘Halcyon‘ in the dark plate. Over the years this patch slowly spread until it became a flat intrusion in its visually complex surroundings.

So at Oudolf’s suggestion, we decided to break up the existing hosta and interplant it with a beautiful, airy grass called moor grass ‘Poul Petersen’ (Molinia caerulea ‘Poul Petersen’). We expect that these plants will have similar rates of spread, and we hope that their contrasting textures will complement each other well. When the hosta looks lush and robust in early summer, the moor grass is small, but when the hosta begins to fade towards the end of summer, the moor grass visually takes over with airy flower clusters and seed heads that provide texture into the winter.

That same mass of hosta ‘Halcyon’ after moor grass ‘Poul Petersen’ was brought in to break it up. Even for those of us who spend significant time here in the garden, it can be hard to remember where everything is, let alone be able to clearly articulate that knowledge to our volunteers who come to help. The present has a way of eroding the details of the past so that we begin to think that today’s conditions have always existed.

In the past, this planting history has existed only in the heads and notebooks of Oudolf and our horticulture staff. Additionally, this information can be hard to communicate to others, and no matter how well it is written down, it is in danger of being lost with the changing of the guard over the years. There are, however, some useful tools to help address this difficulty of memory and communication.

Flowering Time Records

The first tool is a consistent record-keeping system. Beginning in 2008, our former Volunteer Manager, Melanie Scott, sent out an email twice a week to our volunteers containing a document listing what was blooming in the garden that day. Volunteers who worked as docents giving tours to garden visitors would use those sheets as reminders of plant names, helping to enrich visitors’ experiences. Late last year when looking through these records to try to identify a particular phlox whose name had been lost, we realized what an incredible resource this information represented – we had data from the last 12 years about when each species started and finished flowering in the garden. Our horticulture staff has continued collecting this data, and has entered it into a spreadsheet, making it easy to search, sort, and combine with other information.

We send these lists of blooming plants to our volunteers throughout the growing season to let them know what’s blooming in the garden – a practice that began in 2008.

Entered into a spreadsheet, this information allows us to compare bloom times between species and across years to inform planting combination timing decisions.

Mapping

Mapping is another important tool often used for record-keeping in many botanic gardens, where each plant typically exists alone in a particular place. Keeping a map for a garden with intertwining, dynamic plant combinations like those in Lurie Garden can be more difficult, and so precise mapping isn’t traditionally used in gardens like ours.

When the garden was first installed in 2005, a set of detailed layer maps of the design was used to indicate plant placement within the framework of the garden. While relatively specific, these maps were intended as a guide and assumed the presence of the designer for final interpretation. At irregular intervals over the last 15 years, those maps have been updated, allowing us to visualize where plants had moved. Each iteration of the map has shown a record of where species were located that year, as some things spread or died out naturally, while others have been added, moved, or removed by the garden team. You can imagine that it is difficult to update a static printed map.

Updates to the Lurie Garden Map have been made intermittently in different programs since the garden’s creation. Map credits: Piet Oudolf, Krista Wlodek, Megan Wade, Yaritza Guillen and Peter Slothower.

Over the past year, using the most recent map and actively verifying each patch’s footprint in reality as it were, we brought the garden map into a dynamic geographic information system (ESRI’s ArcGIS platform) with plant data (i.e. name, color, etc.) connected to each space. We are establishing a viable workflow that will help us keep our maps updated into the future – starting with a clear system for consistent data collection and map updates, resulting in maps that act as both historical records as well as dynamic design and maintenance tools.

We draw edits to the shapes of the planting blocks and overlays. The polygons are then updated in the mapping software. Those polygons are then connected to data on each species of plant.

This resulting visualization helps bring plant combinations to life in a way you may not notice on the ground or from day to day or visit to visit – you can see that the blooms of the meadow sages in the salvia river alternate in waves of blues and purples from May until June, or that when the Virginia bluebells finish blooming, the goatsbeard starts.

Map of the “Salvia River” when the meadow sages are at peak bloom in early June. Four different meadow sages with different tones of blue and purple repeat through this section of the garden, simulating waves in a river. While not everyone will notice this at ground level in the garden, seeing them on the map draws attention to this design feature.

The “Salvia River” at peak bloom at that same time period.

This map shows how in late April, only the Virginia bluebells are blooming in this area.

Notice that the Virginia bluebells are no longer visible on the map in June and the Goatsbeard ‘Horatio’ has taken its place. These maps are from the same dates as the pictures shown at the beginning of this post.

This new approach is allowing us to explore our garden in new ways and is showing us new questions that we hadn’t known to ask. For instance, since taking over as Director and Head Horticulturist of Lurie Garden, Laura Ekasetya has made it a specific goal to continually increase our native plants.

With good plant records, this is a seemingly easy goal to track – we now have 165 species that are native to the Chicago region, the US Midwest, or a cultivated form of one of those species, versus 131 species just 18 months ago – an increase of 26%. But how can the actual coverage of those plants in the garden be estimated considering we’ve only collected bloom timeframes? With our dynamic map, and keeping in mind that plants’ spread or footprint can change from day to day, we can now estimate that if all these plants were growing at the same time, at least 68% of the garden’s surface area would be covered.

This visualization displays the locations of all native plants in the garden – not all of which are growing at the same time.

Remember the Virginia bluebells (Mertensia virginica) we discussed earlier? Our map can tell us where they are in the garden, and it can tell us that, on average, they can be found blooming in the garden from April 21 to May 27 each year but it cannot tell us how long its foliage is present. Outside of a plant’s flowers, a plant’s leaves and seed pods are not only important design elements but they provide soil coverage and insect habitat for wildlife. Anecdotally, we know Virginia bluebells are contributing to the garden in these ways as early as early-March and as late as the end of June, but this is not yet being recorded.

Native plants blooming in the garden on June 17, on average from 2008-2019. We know that common milkweed (Asclepias syriaca), rattlesnake master (Eryngium yuccifolium), and white false indigo (Baptisia alba var. macrophylla) are all growing during this time, but only the white false indigo is not shown on our map.

Expanding on this idea, our map can tell us that on June 17, on average, 27% of the garden has native plants blooming on it. But while flowers are important for pollinators, the foliage of the plants also play a large role in supporting our food webs. For example, many insect species utilize plant leaves at some point in their life cycle. We have detailed data about where plants are rooted, and when they’re blooming, but we haven’t tracked how much foliage plants have throughout the year.

White false indigo (Baptisia alba var. macrophylla) – also known as white wild indigo- is native to the Chicago Region. It usually blooms in our garden between May 26 and June 25. Here it is blooming in the garden, and showing on the map as blooming in that location, both on June 17.

Piet Oudolf surveys the garden’s Dark Plate meadow on October 2. White false indigo has a sturdy presence and high ecological value in the garden at this time despite not being in bloom.

As you can see the white false indigo does not appear on the map on October 2 because it is not flowering. The foliage of this plant emerges in April, and the seedheads can last well into winter, adding to the garden composition and ecological value for a large portion of the year.

While white false indigo blooms supply pollen for queen bumblebees in late spring, their leaves are eaten by the caterpillars of several moths and butterflies throughout the season. In fact, the wild indigo duskywing butterfly (Erynnis baptisiae) is so named because its caterpillars are so often found on false indigo! Photo Credit: The Field Museum.

An additional advantage of our interactive mapping system is that we hope it will allow us to share more information with garden visitors without adding visual clutter. While some signage highlighting plants may be valuable, too many signs can be distracting from the naturalistic intention, and even confusing due to the intertwining nature of our plants.

How many visitors would know which of these plants are twinleaf (Jeffersonia diphylla)? Unlike a botanic garden, we never label more than a dozen plants in the garden at a time – as our number one objective is beauty and design. More importantly, we’ve found that our plants are often growing shoulder to shoulder with others, so it can be hard to tell what the signs refer to!

Most visitors to the garden seem to be satisfied with these signs identifying key species and with our larger windmasters around the edges of the garden showing seasonal highlights, but we also understand that there are those who are eager for more information. In an effort to help with plant identification, we have added an interactive version of the map we’ve developed to our website that allows those who are interested in learning more to navigate to any location in the garden and find out what plants are there. Specifying a specific date or date range to see what’s blooming in any location at that time is also possible. Remember, you can always send a picture to info@luriegarden.org of a plant in the garden you’d like to know the name of and we’d be glad to help!

This web map shows the average flowering times (across the years we have data) of all the species overlaid over the garden. By default, the map is set to show the whole season, but by sliding the bar, users can go to any day or range of days during the growing season, and see what’s happening then. Click here to explore!

As our mapping continues to develop, we plan to keep creating more iterations that help us and friends of the garden visualize our changes and make new plans – and add ecological value as we do this.

One of our key values is to help people learn more about the natural world and discover the beauty of gardening in a naturalistic style. Our plant finder has a wealth of information about each plant, and we encourage anyone interested to dig in or reach out to us with questions! Our programming offers amazing resources – from botany basics to container gardening, and from bird watching to expert lectures – that we hope you’ll take advantage of.

What else do you think would be helpful? What maps would you like to see? Let us know in the comments below!

Cover image – Drone Photo Credit: Devon Loerop Media; Map Credit: Peter Slothower.

Peter Slothower is Lurie Garden’s GGN Public Garden Apprentice and Assistant Horticulturist.
Meet more of the garden’s staff here.


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