Philadelphus

( fi - luh - DEL - fuss )

At-A-Glance Information

This genus of flowering deciduous and evergreen shrubs includes species commonly called Mock Orange that need partial shade in warmer climates and moderate to regular water to perform well in the garden. The flowers will attract butterflies and other pollinators to the landscape. Blooms are present in late spring or early summer, usually in cream or white. They are fragrant in some species. Use these shrubs as specimens in mixed beds and borders, as an informal flowering hedge, or planted near windows or doors where their floral scent can be enjoyed from inside. They can also be espaliered.

Philadelphus Species and Varietals

The genus Philadelphus includes 60 species and is a member of the plant family Hydrangeaceae. Plants in the genus are closely related to those in Deutzia, Hydrangea, Carpenteria (Tree Anemone). The best growing zones for Mock Orange vary depending on the species. For more information, see the descriptions below. To find your zone, click here: Zone Map.

Philadelphus coronarius (Sweet Mock Orange, Mock Orange, English Dogwood)
This species is native to southern Europe and the Caucasus and is best in USDA hardiness zones 4-8 and Sunset growing zones A1-A3, 1a and 2-24. They reach up to 10-12 feet tall and wide with very fragrant flowers. Cultivars include 'Aureus' (to 8 feet tall and 5 feet wide with bright golden foliage that turns yellow-green in summertime), and 'Variegatus' (with leaves edged in white).

Philadelphus spp. Hybrids (Hybrid Mock Orange)
These plants were bred for their size, climate and disease resistances, and flowers. Cultivars are listed and described below:

'Buckley's Quill'
Deciduous tree with dense compact habit to 4-5 feet tall and wide. Fragrant double blooms have narrow petals.

'Belle Etoile'
Deciduous, to 5-6 feet tall and 8 feet wide. Single white blooms with maroon centers. Fragrant flowers.

'Glacier'
To 5 feet tall and wide with fragrant double blossoms.

'Manteau d'Hermine'
Deciduous, to 2-3 feet tall and 4 feet wide. Double flowers with heavy fragrance.

'Minnesota Snowflake'
Deciduous; reaches 6-8 feet tall and wide with double flowers. Dwarf form available to half the size.

'Natchez'
Deciduous to 8-10 feet tall and just as wide. Double flowers bloom profusely.

'Virginal'
Deciduous plant reaching up to 6-8 feet tall and just as wide. Fragrant double flowers.

Philadelphus lewisii (Wild Mock Orange, Lewis' Mock Orange, Syringa, Indian Arrowood)
Deciduous species native to western North America, grows well in USDA hardiness zones 4-9 or Sunset growing zones 1-10 and 14-24. To 4-10 feet tall and just a bit wider at maturity. Single flowers have satiny white petals. This is the state flower of Idaho. Cultivars include 'Goose Creek' (with double flowers to 8 feet tall and wide), 'Blizzard' (cold-hardy with fragrant white flowers), and 'Waterton' (compact and profuse early summer blooms).

Philadelphus mexicanus (Evergreen Mock Orange)
This species takes the form of a vining shrub, and is native to Mexico. Evergreen foliage and creamy white clusters of flowers. Reaches 6 feet tall and wide as a free-standing shrub, and if given support, can climb up to 15-20 feet. Grows best in USDA hardiness zones 8-11 or Sunset growing zones 8, 9 and 14-24.

Philadelphus microphyllus (Littleleaf Mock Orange, Desert Syringa)
This deciduous shrub grows well in USDA hardiness zones 5-9 or Sunset growing zones 1-3, 7, 10, 14-16 and 18. It is native to the southwestern United States and Mexico, and is 4-5 feet tall and wide. Very fragrant flowers. Endures some drought.

Caring for Philadelphus

Plant Philadelphus in a space in the landscape that receives full sun to partial shade; ideally, they appreciate about 6 hours of sun each day. Ensure that soil is well-draining, rich in nutrients, and has a pH of between 4.0 and 7.0 (acidic to neutral). If local soils are particularly poor in nutrients or do not drain well, make sure to amend the planting area with plenty of organic compost before installing. Apply a layer of mulch around the planting area to suppress weed growth, maintain consistent soil temperatures, and to increase soil moisture retention. Water new plantings regularly as they establish a strong root system in their new home. At maturity, these shrubs are considered drought-tolerant, able to get by on rainwater alone for much of the year with supplemental waterings during extended periods of drought.

Fertilize yearly in early springtime with an application of 2 inches of compost around the base of plants. Pull mulch back before applying, work the compost gently into the soil a bit, water it in, and then replace mulch. Prune Mock Orange shrubs immediately after flowering ceases to remove faded blossoms and to shape the shrub. Avoid pruning these plants heavily; they do not always react well and may not flower as profusely the following year. Prune out any dead or diseased wood at pruning time, as well. Philadelphus shrubs and small trees can survive in the landscape for decades before needing to be replaced.

Caring for Philadelphus in Containers
Philadelphus shrubs are wonderful in the ground, but can also be grown in containers. Choose a container that is at least a few inches wider and deeper than the nursery pot or root ball. Ensure that the pot has adequate drainage holes on the bottom to allow for excess water to flow away. Fill with a well-draining potting mix amended with organic material and perlite, and top with a layer of mulch to suppress weed growth, maintain consistent soil temperatures, and to increase soil moisture retention. Water regularly as the plant establishes itself in its new home. Once established, waterings can be lessened. Mock Orange plants grown in containers will need more frequent irrigation than those grown in the ground. As a general rule of thumb, water whenever the top few inches of soil feels dry to the touch. Prune to remove dead, damaged, or diseased foliage at any time during the growing season. Every few years, check the bottom of the pot to ensure that the plant is not outgrowing its root space. If roots are growing through the drainage holes in the bottom of the container, it is a good indication that it needs to be potted up; choose a slightly larger container and repot.

Harvesting Philadelphus
Philadelphus shrubs produce highly fragrant spring to summer cut flowers. Choose branches for cutting that have mature buds that are just beginning to open up. The best time to harvest is in the morning, after dew has dried but before the heat of the day sets in. Using clean, sharp shears, cut stems at a 45 degree angle just above a node. Strip the leaves below the water line and drop the harvested flower stems into a bucket of cool water. To maximize vase life, split the bottom inch of the stem vertically or scrape off the bark slightly from the base; this will help them absorb water more effectively. Philadelphus flowering stems have a vase life of between 5 and 10 days.

Propagation

Propagating Philadelphus by Cutting

Gather your materials. You'll need a clean, sanitized, sharp pair of garden shears, rooting hormone, a pencil, and a 3-inch pot filled with well-draining compost or other organic material. If you don't have any potting medium on hand, you can make some. Just mix together equal parts (by volume) moss peat and horticultural-grade sand or grit sand.
In late winter or early springtime, choose the plant that you'd like to propagate. Ensure that this plant has had a good watering the night before, as this will improve the chances your cutting will take root. Cut one or more 6 inch hardwood portion(s) of the end of a non-blooming branch and strip the leaves off of the lower half. Make a hole in your planting medium by pushing your pencil into the soil. Dip the end of the stem in rooting hormone, and plant it in your pot. Fill in soil around the cutting to support it, but do not pack it down too much.
Moisten with water, and ensure that the pot has good drainage. Your pot should be kept in warm, sunny conditions indoors (and not in direct sunlight). Water whenever your soil is dry under the top layer. After about four to six weeks have passed, your cutting should be rooted. When you notice new growth, you'll know you have roots.
Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring, when you can transplant it to its new home. Ensure that the last frost of the year has occurred before doing this, as it can seriously damage your new shrub.