Mother Nature's Montrose Garden: June 2021

Mock Orange (Philadelphus lewisii):

Long-blooming flowering shrubs are justifiably popular. They add beauty to the landscape, while also providing nectar and pollen for the many pollinators visiting a summer garden. One of our western favorites is the Mock Orange, Philadelphus lewisii (pronounced fil-uh-DEL-fus loo-ISS-ee-eye). Our Philadelphus shrubs often bloom through most of June and into July.

Philadelphus lewisii is known simply as Mock Orange or as Lewis', Gordon’s, Wild, Western, Pacific, Idaho or California Mock Orange; in some places, it’s also called Indian arrowwood (it’s woody stems have been put to many uses, including as arrow shafts). The genus Philadelphus was named by Linnaeus after Pharoah Ptolemy II Philadelphus. The species name honors Meriwether Lewis, Western U.S. explorer who collected the plant.

The genus Philadelphus contains approximately 60 species native to North and Central America, Asia, and southeastern Europe; about 27 Philadelphus species are native to North America. [1] Only one species, Philadelphus microphyllus (Littleleaf Mock Orange), is native to Colorado. Other Western Colorado genera in Hydrangeaceae (the Hydrangea Family, to which Philadelphus belongs) are Fendlera, Fendlerella and Jamesia. [2]

Mock Orange (Philadelphus lewisii): in nature

Philadelphus lewisii is native to northwestern United States and southern Canada. It occurs from extreme southern British Columbia south to California, and east to north and central Idaho, western Montana, and southwestern Alberta. [3] In its native range it commonly occurs in open coniferous forests and forest edges, usually associated with other shrubs. It is found in a range of plant communities, often along stream sides and moist open woodlands; it can also grow on dry, rocky hillsides, in pine forests and in sagebrush deserts. Fortunately for gardeners, it also does well in gardens across the west and beyond.

Mock Orange (Philadelphus lewisii): growth habit

Mock Orange is a multi-stemmed, winter-deciduous shrub. It commonly grows 4-6 ft [ m] tall and wide, although some plants grow to 10 or more ft. tall. The growth habit is usually mounding to vase-shaped, though plants may be loosely sprawling or arching. The growth pattern and flowering characteristics are quite variable between plants and locations. Growth rate ranges from moderate to fast.

Mock Orange (Philadelphus lewisii): foliage

Mock Orange (Philadelphus lewisii): fall color

The leaves of Mock Orange are oval, opposite and may have serrated edges. Leaves start out light green in spring, becoming medium green in summer. Leaves usually turn yellow in fall. The bark of twigs and young branches is reddish-brown, becoming gray and flaking with age. When not in bloom, the plant is a pleasant green shrub that makes a good backdrop for showier species.

Mock Orange (Philadelphus lewisii): flowering plant

But when Philadelphus lewisii blooms, the shrub becomes spectacular! A mature plant can be covered with hundreds – even thousands – of blooms. The flowers grow in clusters along a flowering stem. Individual flowers are up to 1 ½ inches across and pure white. The flowers are heavily scented with an aroma similar to that of orange blossoms (hence the common name of Mock Orange). Flowers are pollinated primarily be bees, though butterflies also visit the flowers.

Mock Orange (Philadelphus lewisii): close-up of flower

Mock Orange (Philadelphus lewisii): green sepals

Plants bloom from late spring into early summer – as long as a month or more in our part of Western Colorado. Flowers have four (sometime five) petals and numerous yellow stamens. The green sepals remain after the petals fall – an interesting look in its own right (above). The fruit is a small hard capsule (a centimeter long) with woody wings, containing many brown seeds. New plants can be started from seeds scattered in fall, or pre-treated (cold-moist treatment for 2-3 months) and planted in spring.

[capsule and seeds – coming soon]

Mock Orange is an adaptable plant in the garden. It can thrive in a wide range of soil textures, with pH from 5.0-8.0. It is quite hardy and can be planted from USDA Zone 3 to 9 (most Sunset Zones). It is fine in full sun to part-shade (morning sun) and fairly drought tolerant once established. In hot, dry gardens of Western Colorado it does best with a weekly deep irrigation during the summer months.

Mock Orange (Philadelphus lewisii): does well in part-shade, particularly
in hot gardens

Mock Oranges benefit from some yearly pruning. Like Lilacs, yearly removal of the oldest ¼ to 1/3 of branches helps renew the plant and promote abundant blooms. Old, neglected plants can be coppiced (cut back almost to the ground) to renew them. Just be careful using herbicidal sprays around Mock Oranges; they are very sensitive to such chemicals.

Mock Orange (Philadelphus lewisii): in hedgerow with mint groundcover.
Mother Nature's Montrose Garden.

Philadelphus lewisii is an excellent choice for a medium to large shrub. It is attractive from the time of bud-break until it loses its last leaves in fall. It makes a nice screen plant and an attractive addition to a mixed hedgerow. It can be successfully used for erosion control, including along streams and slopes. It is equally at home in a natural or woodland garden as it is in a more formally manicured design. Shrubs are effective both as specimen plants or to provide a background for other shrubs or flowering plants.

Mock Orange (Philadelphus lewisii): in garden.

Mock Orange (Philadelphus lewisii): Rancho Santa Ana Botanic Garden.
Claremont, California

Of course, the flowers - with their fragrance and long season - have made Mock Orange a popular garden shrub since first introduced into English gardens in 1825. In fact, this shrub has an old-fashioned appearance; it would look right at home in a Victorian or Edwardian-themed garden. And one can’t ignore the habitat value of Mock Orange. It supports pollinators from native bees to butterflies. The seeds are eaten by many birds including grosbeaks, juncos, thrushes, bluebirds, flickers, quail, chickadees and finches. [4]

Mock Orange (Philadelphus lewisii): nectaring Lady Butterfly

Mock Orange also has several traditional human uses. The flowers can be used to prepare perfumes and teas. Dried, powdered leaves were traditionally mixed with oils and applied to sores and swollen joints. Leaves and flowers contain a high concentration of saponins. They can be used as a gentle soap or shampoo. Just whisk bruised plant materials in water; or wet your hands and rub the plant materials between your hands to create a lather.

The hard wood has traditionally been used to make bows, arrows, combs, tobacco pipes, cradles, netting shuttles – even knitting needles! Stems were also used in coiled basketry.

Mock Orange (Philadelphus lewisii): four year old 'Blizzard'

A number of cultivars of Mock Orange are available from nurseries. In fact, the cultivars are likely more readily available than the straight species. In Mother Nature’s Montrose Garden we grow both ‘Blizzard’ and ‘Cheyenne’. ‘Blizzard’, which comes from Canada, is very hardy and more compact (5-6 ft. tall and wide) than some cultivars. ‘Cheyenne’, from Wyoming, grows to 6-9 ft. tall and is known for its sweetly scented flowers.

Mock Orange (Philadelphus lewisii): three year old 'Cheyenne'

The cultivar ‘Covelo’ has very dense foliage (good for hedge or screen) while ‘Goose Creek’ and ‘Marjorie Schmidt’ (both from N. California) have double flowers. ‘Mount Tahoma’ has variegated leaves and ‘Snow Velvet’ has large, 2 inch flowers on an 8-9 ft. plant. ‘Waterton’ is known for its drought tolerance.

In summary, Mock Orange is a favorite shrub for many reasons. While not native to Colorado, it grows in neighboring states and does very well in gardens of the Four Corners states. It’s a nice-looking shrub most of the year. And when in bloom it is a show-stopper. This is one of those old-time favorites that looks good in most types of gardens, from formal to very informal. It has a wonderful scent and provides good habitat value for its size. If you’re looking for a medium to large shrub, take a closer look at Philadelphus lewisii and its cultivars. You may decide that Mock Orange is just what your garden needs.