The Gravel Garden

In the Garden with Andrew

Andrew Bunting. Photo courtesy of the Pennsylvania Horticultural Society.

For some time, I have been drawn to the aesthetics of a gravel garden. The plant palate can vary from prairie to Mediterranean to desert. The gravel garden’s aesthetic is definitely modern. 

My first glimpse of this style of garden was at John Brookes’ Denmans, in England, in the summer of 1990. In the U.S., work by Jeff Epping at Olbrich Botanical Garden in Madison, Wisconsin, and Roy Diblik at Northwind Perennial Farm in Lake Geneva, Wisconsin, catalyzed a new way of American gardening. In this area, we have a wonderful example below the ruins at Chanticleer in Wayne, created by Lisa Roper, a Chanticleer horticulturist from Wallingford. 

Gravel gardening was originally promoted in Germany as a way to grow drought-tolerant plants that require very little watering. Once the gravel garden is established, it needs no fertilizing and has very few weeds. Many gravel gardens plants are prairie natives with deep root systems. Many are great attracters of pollinators. Most important, this type of gardening requires no fossil fuels or chemicals.

Swarthmore boasts a gravel garden in the center of the roundabout in the middle of town. This gardening masterpiece is the work of Adam Glas and Jeff Jabco of the Scott Arboretum of Swarthmore College, working with Bill Conwell Landscaping.  

To make a gravel garden, first remove the top five to six inches of soil. Then add approximately two inches of quarter-inch granite gravel and rototill it into the existing soil. Finally, add an additional four inches of gravel on top. 

One of the keys to a successful gravel garden is planting the plants in pure gravel. They root in the gravel, then ultimately down into the soil below. By that time, the four-inch top layer is so dry and porous that it is nearly impossible for weeds to establish themselves. 

The Swarthmore traffic circle garden is peaking right now. It contains a simple yet provocative mix of about 12 kinds of plants, including two ornamental onions (Allium), ‘Miami’ and ‘Ambassador’, with large, globe-like purple flowers. The silver-blue foliage of a spreading juniper called ‘Grey Owl’ provides both structure and winter interest. A thread-leaf bluestar with sky blue flowers, Amsonia hubrictii, and the stunning sulfur-yellow flowers of Baptisia australis ‘Lemon Meringue’ combine with the Allium to make this a picture-perfect garden. Two perennial salvias, ‘Caradonna’ and ‘Blauhugel’, are also blooming, deep purple and light blue. 

‘Miami’ and ‘Ambassador’ Allium are currently peaking in the roundabout garden. Photo: Andrew Bunting

Several smaller adjacent beds, as well as beds leading into the college down Fieldhouse Lane, feature similar plantings.

At home on 408 Vassar Avenue, I have long used gravel for pathways or topdressing. But until this spring, I had not tried true gravel gardening myself. 

In 2019, I returned to Swarthmore after years in Chicago and Atlanta to find that my front yard had become too rambunctious for even my tastes. What was once a cottage garden had become more of a wild garden. By late summer, it was practically unmanageable. 

In the fall, I started relocating plants I wanted to salvage. Then, with Bill Conwell Landscaping, I followed the steps prescribed by Jeff Epping in Wisconsin and Adam Glas and Jeff Jabco at Scott. 

Andrew Bunting’s new gravel garden on Vassar Avenue in Swarthmore. Photo: Andrew Bunting

I love the excitement of making a new garden and getting to use a whole new palate of plants. I am no expert in this type of gardening, but what I always like most about gardening is the trial-and-error process of finding successful plants and methods. To my eye, the gravel aesthetic might go even better with the midcentury modern house across the street, but it is a nice complement to my stone house nonetheless. 

I would encourage everyone to admire the phenomenal plantings in the center of town. But also come down Vassar and see my project.

Reader Questions:

Jen Pfluger of Swarthmore asks, “What might be eating my Carex Everillo, and are there Carexes that are less tasty?” 

Carex is the Latin name for sedges. Sedges have gained in popularity in the last 15 years. Many are native and generally deer resistant. Most likely rabbits are chewing on Jen’s sedges. More compact types like Carex pennsylvanica and Carex appalachica might be more rabbit-tolerant.

Rachel Pastan wants to know, “When is the best time to prune my witch hazel?”

In general, I reply to any pruning question by asking, “Do you need to prune?” Most plants simply do not need pruning. However, if you need to reduce size, rejuvenate a plant, remove dead branches, or fix structural issues, I recommend winter pruning for deciduous plants like the witch hazel. If you did not do it then, I would suggest a mid-summer pruning in early August.

Tips: 

Now is the perfect time to plant your annuals and summer tropical plants. After May 1 is generally safe for planting annuals, although this year, due to cold weather, it was more like May 15. The Swarthmore Horticultural Society is currently installing plants in the 13 public gardens throughout the borough. Garden Manager Ron Ricchezza planted one of my favorite summer annuals, Persian shield, Strobilanthes dyerianus, at the Post Office. A beautiful elephant ear with purple-black leaves, Colocasia ‘Black Swan’, is going in front of the Swarthmore Public Library windows.

Also, now is a great time to plant sunflowers. Last summer’s SHS program “Be a Bee Buddy” is back. If you want free sunflower seeds, just send your address to swarthmorehortsociety@gmail.com, and they will mail you a packet.

Send your gardening questions to editor@swarthmorean.com.

Andrew Bunting is vice president of public horticulture at the Pennsylvania Horticultural Society and vice president of the Swarthmore Horticultural Society.