woman planting shrub

In its ongoing leadership in sustainable, climate-forward landscape management, Cornell Botanic Gardens installed a new gravel garden that saves water, promotes sustainability, and increases biodiversity, especially among pollinator insects.  It is the first of its kind on the Cornell University campus and will require many fewer inputs than a conventional garden space.

Horticulturists at Cornell Botanic Gardens converted a large garden bed at the south end of the Lewis Building by removing existing plants, preparing the soil, and installing gravel at an exacting depth to provide for drainage, soil temperature regulation, and inhibit weed establishment. Ten tons of gravel were installed in the 765-square-foot bed.

The gravel acts as a semi-permeable seal, blocking weeds from taking root and preventing water from escaping said Emily Detrick, the Elizabeth Weaver Director of Horticulture at Cornell Botanic Gardens.

“A top layer of gravel means fewer annual mulch inputs and less weeding and watering,” Detrick said.  “The gravel topdressing helps to hold in moisture and prevents evaporation. Even though it feels and looks hot and dry on the surface, we go down just a couple of inches and it’s quite moist below.”

Detrick selected plants for the new garden that are deep-rooting and drought tolerant but notes that these include diverse species that may not immediately be thought of as drought tolerant, such as bee balm and mountain mint. 

“Plant selection is composed of large, herbaceous perennials — not succulent, xeriscape type plants that one might initially imagine when they hear ‘gravel garden’,” Detrick said. “Once established, the plants will fill in the space, shading and cooling the gravel surface so there is not a heat-island effect.” 

Plants were also chosen for their ability to attract various beneficial insects, including pollinators such as native bees, butterflies, and some pollinating flies.

Other plants are important larval hosts for native moths and butterflies, such as red pine and columbine, and some, like calico aster, attract predatory or parasitoid insects that prey upon pest insects.

Carefully selected non-native plants provide visual interest and extend bloom time and thus the availability of pollen and nectar sources for insects. These plants include Crocus in the early spring, Anemone hupehensis in the fall, and Alchemilla, whose densely hairy leaves have a unique water holding capacity beneficial to insects.

Spaces that foster plant-insect interaction and a rich biodiversity of insects literally keep the world green, said John Sanderson, professor emeritus of entomology at Cornell’s College of Agriculture and Life Sciences.

 “Insects have tremendous value not only in their beauty but also in their intricacies with nature,” he said. “If we were to lose insects, our ecosystem would deteriorate in a very short period of time.”

The new garden’s approach to enhancing  plant-insect interactions will make it a source of knowledge on how to create spaces that are resilient to the changing climate.

“The garden will be ever-evolving, like all of our gardens here,” Detrick said. “We will adapt as we see which plants do well in this area and  uncover stories we don’t even know yet.”

Anna Hooper ’25 is a communications intern at Cornell Botanic Gardens