When I moved to Idaho a number of years ago, I would occasionally hear about syringa in reference to a plant. I thought, “Wow, all these people know the botanical name for lilac.”
Of course, they meant our state flower, the western syringa, or Lewis’ mock orange, a plant that is often superficially admired but deserves a deeper look for inclusion in our gardens.
Idaho’s own blooming gem
The western syringa is a deciduous shrub native to western North America, including Idaho, Montana and to the coast. It is the local species in the group of plants commonly called mock orange.
The plant, philadelphus lewisii, is named after the explorer Meriwether Lewis, who first collected specimens for scientific classification in 1806 along the Clearwater River in Idaho.
Goose Creek flower closeup. | Jared Gibbons, UI Extension Educator, Madison County
In those days the plants grouped together in a family named syringa, (with the unrelated lilacs, syringa vulgaris), had sweet smelling flowers and hollow stems-syringa comes from the Greek syrinx meaning tube.
Whatever you want to call it, it was officially chosen as Idaho’s state flower in 1931.
As for me, I can’t bring myself to call it syringa because I automatically think lilac. The woody shrub typically grows to a height of 5 to 10 feet, sometimes reaching 8 to 12 feet tall and 5 to 8 feet wide at maturity, with an upright, though potentially loosely-branched form.
It truly shines in late May or June, when it produces large, white, four-petaled flowers, typically 2 inches in diameter, often appearing in clusters of three to 15 on its branches.
The blooms typically last about three weeks but sometimes extend into July.
What makes it truly captivating is the strong, sweet and orange-blossom with a hint of gardenia fragrance that emanates from the blooms.
Bringing Idaho’s native beauty to your yard
Lewis’ Mock Orange is remarkably adaptable, with habitats from moist riparian areas and dry ravines to wooded or brushy slopes, open forests and even disturbed areas.
Syringa flowers. | Courtesy of Sierra Laverty, UI Extension Educator, Ada County.
For the home gardener, this means ease of cultivation:
Soil: It tolerates most well-drained soil types and, while it may prefer gravelly and nutrient-rich soils as is found in the mountains, it is not overly particular. Although it has been known to develop iron chlorosis in heavy clay soils in our area. Sun/Shade: It performs best in full sun but still well in part-shade. With at least half a day of direct sunlight you will still get good blooming. Watering: While moderately drought-tolerant, infrequent but deep irrigation during summer months will help it remain attractive; stressed plants may show curled and folded leaves. Pruning: To prevent it from becoming leggy and to encourage prolific flowering, light routine summer pruning is recommended to remove aging interior branches, spent flower clusters, or to control its size and improve its form. Avoid spring pruning, you will cut off the flower buds! Pests and Diseases: One of its great virtues is its resilience; Western Syringa has no significant insect or disease pests. Landscape Use: It makes a great addition to a backyard woodland, is effective as a screen, or it can be used as a specimen or accent plant, especially the more prim and proper cultivars. Plant it close to outdoor living areas to enjoy its strong fragrance. Cultivars: While I don’t often see this specific mock orange species at local nurseries, a number of cultivated varieties are readily available from local and mail order nurseries.
‘Cheyenne’ (6- to 9-feet high, 5- to 8-feet wide) is a drought tolerant cultivar with smaller flowers but some continual flowering after the first flush. It was selected from seedlings at the USDA Research Station near Cheyenne Wyoming.
The ‘Goose Creek’ (5- to 8-feet high, 4- to 6-feet wide) cultivar has exceptional double flowers, meaning two or more layers of petals.
‘Blizzard’ (4- to 5-feet high, 3- to 4-feet wide) was selected from a seedling population in Beaverlodge, Alberta, Canada, it is very hardy to USDA Zone 2B or 3 (great for you cold area folks in the Teton valley, or Island Park) and the profuse production of larger flowers last past a few weeks to a month long.
A haven for wildlife (and your senses)
Although the native range does not extend into eastern Idaho area, it remains an excellent choice for our yards. Its fragrant flowers are a magnet for pollinating insects, including swallowtail butterflies, bumblebees, and honeybees. Later in the season, its seeds become a food source for various birds.
By planting this native mock orange, you are not only adding a beautiful plant to your garden, but also contributing to a richer, place-specific garden style that stands apart.
Philadelphus lewisii is a choice that every gardener should consider.
Jared Gibbons is the Extension educator in Madison County. Contact him at jaredg@uidaho.edu.
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