Philadelphus – Mockorange

Nearly everybody has met the memorable fragrance of mockorange, said to imitate the smell of orange blossoms. There are over a hundred species of Philadelphus, and of these, about 40 are native to North America. Many of the yards of Boulder County and Denver have at least one specimen. What is so good about this shrub? Dirr says, “In flower they are attractive to some, but the rest of the year are real eyesores.” Wyman said their fall color is not vivid, their fruits are not ornamental, no winter interest, but they are “cultivated 50 weeks of the year in order that their flowers may be appreciated for two weeks.” However I happen to love mockorange, and one of the 2001 Plant Select shrubs is ‘Cheyene’ Mockorange. So let’s look into the good qualities.

            I must admit, I will forgive a lot for fabulous fragrance and many, but not all Philadelphus will simply stop traffic with their redolence. I remember getting out of my truck in Boulder and being captured by a smell that seduced me to follow it to its source, which I found in the back yard over 100’ away. It was a 10’x8’ old Philadelphus coronarius growing practically uncared-for, on the edge of an alley. Wyman was from the east and Dirr is from the southeast; these horticulturists don’t have the respect for “tough” that we have here in Colorado.

         Philadelphus has a massive root system capable of drawing moisture and nutrients from a wide area. They are adaptable to a variety of soils, will thrive in full sun or part shade; they love moisture, but many varieties tolerate drought. They are vigorous, often bloom young, and make good screens, which make them attractive to people with new houses and landscapes. They are not susceptible to any serious pests or diseases; they do well with little attention and they are easy to transplant. Many are very cold tolerant. Add to that a fragrance that touches the soul, and I’m ready to share a little of my water with one.

         Philadelphus coronarius is from Europe and is commonly found in gardens though the plain variety is seldom sold in nurseries anymore. It is one of the most fragrant with single white flowers and one of the most drought tolerant. It will grow 8’-12’ high and wide and has a coarse habit and “bare legs”. Philadelphus microphyllus is a Colorado native with small leaves and short habit to 3’-4’. The flowers are smaller and there are mixed opinions as to its fragrance: some say very fragrant, others say little fragrance. Mine did not bloom well in full sun and drought. A French hybridizer, Victor Lemoine, crossed P. coronaria with P. microphyllus to create P. x lemoinei of which there are several desirable selections: ‘Avalanche’ is only 4’ high with very fragrant single white flowers; and ‘Conquete’ and ‘Mont Blanc’ are both highly fragrant.

Lemoine also crossed P. lemoinei with P. nivalis and got P. x virginalis of which ‘Virginal’ is the best known for its great fragrance. However it is not as cold tolerant and the shrub form is more open and bare, and it prefers more water. ‘Minnesota Snowflake’ is a very cold hardy, double, fragrant variety to 8’ and its dwarf form ‘Miniature Snowflake’ is similar but only growing to 3’. Another good variety is ‘Snow Goose’. It is cold hardy, with very fragrant double flowers in profusion.

         Philadelphus lewisii is a western native discovered by Meriwether Lewis and named after him. It is the state flower of Idaho. At the Cheyenne Research Station only one mockorange survived over 20 years of neglect and drought, and this P. lewisii shrub is actually thriving and blooming. It is from this specimen that the 2001 Plant Select shrub was propagated and was named ‘Cheyenne’. It grows to 7’ tall and almost as wide with large, single, very fragrant white flowers in early summer. Hardy to zone 3 and 8000’ it can grow moist to dry, in sandy loam or dry clay.

         Since so many modern shrubs have been selected for appearance, fragrance has often lost out. However mockorange had little else to select for and so many newer varieties have great fragrance. Still, mail order may bring disappointing results as it did for me, so go smell them in flower at the local nurseries to make the best choices.