A tiny rectangular sign read “3 miles to go.”
The meandering gravel road into The Arboretum at Flagstaff led us on an uncertain ride as we followed a long line of vehicles kicking up plumes of red clay dust. After the dance, our car’s tires emerged with a rosy glow.
We were at 7,150 feet above sea level at The Arboretum. Surrounded by the native ponderosa pine trees, we felt a cool breeze through the woods that made a sharp contrast with the low desert region, and its 100-degree temperatures.
High Desert Meadow Gardens at The Arboretum
The Arboretum is on the western side of Flagstaff where there is an alpine meadow, and lies in the shadow of the San Francisco Peaks. In the northeastern section of Arizona, four states share the bordering area that people refer to as Four Corners.
Gardeners grow plants outdoors in the upper-elevation landscapes surrounded by mountains in the Southwest; enthusiasts call this form of gardening “high desert gardening,” which is distinct from “low desert gardening” that occurs on a valley floor at very low elevations.
Plants that thrive in the high desert have adapted to extreme temperature swings, short frost-free growing seasons, intense sunlight, windy sites, and in a landscape where water is less abundant.
The Arboretum is on 200 acres and grows roughly 2,000 plant species around the grounds, outside and indoors. Following paved and unpaved footpaths, visitors wander through gardens past the Elderberry Pond and an ephemeral stream called Willow Wash.
Gardens at The Arboretum
Ten gardens make up the collection at The Arboretum. The herb garden looked wild with 250 plant varieties. A simple mix of tansy (Tanacetum vulgare) with viper’s bugloss (Echium vulgare) is a reminder to take notes, as the contrast of yellow and blue would be worth trying in a garden back home.
There is a Square Foot Garden, Courtyard Garden, Shade Garden, Constructed Wetlands, and a Water Conservation Garden. The Penstemon Garden, a Forest Meadow, and a Mixed Conifer Habitat add to the diversity of learning you may experience. The Blue Garden is a collection of plants with blue-green foliage that depicts how flora has adapted to tolerating sun in a high desert environment.
The pollinators couldn’t ignore Rocky Mountain penstemon; they drank up the blue on its tall stalks and cooled down the hot colors from more flowers. Yellow columbine (Aquilegia sp.,) yellow and white yarrow (Achillea sp.,) orange sneezeweed (Hymenoxys hoopesi,) and torch lily (Kniphofia uvaria) make up a large Pollinator Garden where we saw hummingbirds and butterflies going to and fro.
The swaths of the cultivated gardens connect the span of land between forest and meadow, allowing wildlife to continuously find food and shelter.
I spied Heuchera species in a stretch of bed edging a footpath. Heuchera answers to the common name, coralbells, or by the nickname, alumroot. The Arboretum’s display had several Heuchera species and cultivars worth considering for your home garden: H. pulchella, Sandia Mountain alumroot; H. ‘Rose Majesty’; H. sanguinea, the standard coralbells; H. ‘Hercules’; and H. ‘Crimson Curls.’ Heuchera plants live in a high desert garden with low to moderate watering, once the plants are rooted well into the soil.
The Arboretum: Highest Elevation United States Research Botanical Garden
In meteorological terms, the collection of weather extremes around The Arboretum at Flagstaff generates a “cold sink.” It is the highest elevation botanical garden in the United States because of its location on the southwestern edge of the Colorado Plateau.
The Arboretum is a favored botanical spot for investigating plant species and the effects of climate change on their survival.
The Merriam-Powell Research Station (MPRS) and the Southwest Experimental Garden Array (SEGA) are on the public garden’s land and valued for the Ponderosa pine forest with its mix of understory plant species, alpine meadow and ephemeral streams.
The Arboretum’s SEGA Garden Site is one of the newest research landscapes that are part of the garden array. The Rare Species Refugia is another new garden being constructed at The Arboretum.
The Arboretum at Flagstaff is a member of the Center for Plant Conservation. The Rare Species Refugia grows twenty-nine species of rare plants particular to plant communities in the Colorado Plateau. Plants like the sunset crater penstemon (Penstemon clutei,) unique to northern Arizona, and the Holy Ghost ipomopsis (Ipomopsis sancti-spiritus,) special to New Mexico with a federal endangered species status, are part of the collection.
Behind the Horticulture Center and near the weather station used by NOAA (National Oceanic and Atmospheric Administration,) the Solar Panel Test Site stands. The patchwork of solar panels is a mix of sizes and the staff uses each one to trial solar micro inverters for tolerance during extremes of weather. The Arboretum uses the energy generated by the panels to power their greenhouse.
A constructed wetlands and an experimental water treatment facility are more examples of the studies going on at the botanical garden. The facility cleans the water and then uses it to irrigate the gardens by creating a secondary water treatment with three low level ponds where native plants grow. It is here where you will see cutleaf coneflowers (Rudbeckia laciniata) flowering in mass.
Finding a High Desert Public Garden in the Colorado Plateau
Visitors approach The Arboretum at Flagstaff by arriving from the south in the low desert of Phoenix at 1117 feet or from the west in Las Vegas at 2030 feet above sea level, and moving north or east.
Incremental changes in color and vegetative formations in the landscape mark the rise in sea levels well before passing the manmade signage posted along the highway.
On our way to The Arboretum, the sandy floors and dusty scrub foliage dotted with vertical ocotillo (Fouquieria splendens) had just started to green-up in July and native Saguaro cactus (Carnegiea gigantea)– Arizona’s welcome sign– dotted the low desert. But slowly, they gave way to swaths of greener foliage.
We saw rotund pinyon pine (Pinus edulis) and, then, combined plantings of pinyon pine with juniper (Juniperus sp.) announced high elevations at around 5000 feet. At 7,000 feet, forests of Ponderosa pine darkened the scenery casting long dark shadows that seemed to point the way to Flagstaff.
The Arboretum at Flagstaff in Arizona
The Arboretum at Flagstaff in northern Arizona was created in 1981. Primarily outdoors, the research botanical garden is open to the public, where visitors will see native species and plants adapted to growing in the high desert.
Visitors armed with cameras or pens and notebooks will find inspiration worth recording; ideas to grow in their own planting beds back home.
The second half of July is a prime-time for visiting The Arboretum, after summer rains have quenched the thirst of plants living through a dry June.
The Penstemon Festival and Plant Sale is held in tandem on one day in July and gives visitors two events, an excuse to spend all day getting to know this public garden.
A Garden in the Sky
The Arboretum was cast from a forest and in the 1960s was both a working ranch and the home of Frances McAllister. In 1981, she began creating a garden high up in the sky; what is now known as the highest elevation botanical garden in the United States.