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The Garden Scoop

Renovation of Allerton’s Triangle Parterre Garden

If you have not visited the formal gardens at Allerton Park and Retreat Center, near Monticello, I strongly recommend making the trip.  These spectacular gardens combine exquisite landscape design with sculptures from around the globe to create a flowing transition from Robert Allerton’s magnificent, Georgian-inspired home (constructed in 1900) to 1,500 acres of pristine natural areas in the surrounding park.  It is truly a remarkable and historic place in Central Illinois, combining art, history, and elaborate design with the flourishing, unimpeded ecosystem of the Sangamon River corridor.

On a recent visit to Allerton, I was able to connect with Micah Putman, Park Supervisor, to discuss restoration plans for the Triangle Parterre Garden.  This garden was originally designed by Robert Allerton himself, featuring short, conical evergreens with an elaborate triangular-shaped hedge at their feet.  Over time, the ‘short’ evergreens have become tall and added significant shade to once full-sun garden.  In fact, these evergreens have been replaced several times over the 100-plus years that this garden has existed.  Putman is now looking to once again revitalize this garden. 

“The original design called for evergreens no taller than the existing garden walls,” said Putman.  Today, the towering arborvitaes easily reach 3 or 4 times the height of the surrounding brick garden walls, which are somewhere around 10ft in height.  Just as any natural system, the garden has changed over time and much of Allerton’s intended design elements have been lost.

Parterre gardens, like Allerton’s Triangle Garden, are characterized by symmetrical patterns and highly manicured hedges.  They are typically installed in flat, level places on the landscape and include intricate paths and hedges that delimit geometric planting beds.  This garden style originated in France during the 15th century and has become well known across Europe.  The European influence on Robert Allerton is evident in sculptures and artwork, as well as garden design elements throughout the park.

 “In order to recapture Robert Allerton’s original design inspiration, we plan to replant more appropriately sized arborvitaes,“ explains Putman.  Plans also include a renovation of the characteristic, triangle-shaped hedge of aging and invasive privet by replacing it with a boxwood hedge that will revitalize the centerpiece of this garden’s design.

Pathways in parterre gardens are traditionally gravel, sand or mowed grass, which are not as accessible as paved substrates.  In order to provide greater accessibly to the Triangle Parterre Garden and other formal gardens south of the Visitor Center, Allerton staff has installed paved, aggregate paths that mimic the classic pea gravel look of a parterre garden, but provide much greater accessibility. 

 “The new garden will be practical and functional, but still formal,” Putman says in reference to similar accessible features included in the new plan.

Robert Allerton’s original design included some more practical elements, such as food production.  At one point in time, long before the garden’s shade dynamics changed so drastically, plots of sweet corn enjoyed full sun around the border of the Triangle Parterre Garden. 

The new design seeks to capture similar elements of practical functionality in the garden border by incorporating a permaculture planting of fruit and nut trees with interplanted vegetables and herbs.  Permaculture is a set of design principles applied to achieve more “permanent” agriculture.   Perennial plants are typically chosen and are planted in arrangements that mimic nature.  Sustainable productivity is a common goal of permaculture as well, making design with permaculture concepts more appealing to the Allerton staff. “Production areas in the new Triangle Garden will be fun for staff as well as provide excellent educational opportunities for visitors,” adds Puman.

The interesting, historically inspired new design for Allerton’s Triangle Parterre Garden will incorporate aspects of formal garden design as well as permaculture to create a beautiful, yet productive space.  Although a plan has been developed, Allerton’s staff noted that funding for the project will be largely dependent on donor support. Allerton recently initiated a standard that any facility projects, including garden renovations, need to supply an endowment along with the renovation costs - ensuring that gardens like this one are not only restored, but maintained for generations to come. Allerton staff is currently fundraising for this initiative, along with several other large projects identified as priorities in the Park’s 2015 Master Plan.

Ryan Pankau is Horticulture Extension Educator with University of Illinois Extension serving Champaign, Ford, Iroquois, and Vermilion Counties.