How to Grow a Mock Orange Shrub

Mock orange shrubs (Philadelphus spp.) earned their common name with the sweet, citrusy fragrance of their blossoms, which closely resemble orange blossoms. Unlike their namesake, they are hardy and adaptable shrubs that require minimal effort to grow. However, mock orange shrubs will look better and live longer, healthier lives if grown under the best conditions with regular, seasonal care.

The hardiness of mock orange shrubs varies between cultivars, although most grow well within U.S. Department of Agriculture plant hardiness zones 4 to 8. Cultivars such as Avalanche mock orange (Philadelphus "Avalanche") and June Bride mock orange (Philadelphus microphyllus "June Bride") grow best within USDA plant hardiness zones 5 to 9, while varieties such as Belle Etoile (Philadelphus "Belle Etoile") and Miniature Snowflake (Philadelphus "Miniature Snowflake") thrive in USDA plant hardiness zones 5 to 8.

Full sun exposure and moist, moderately fertile soil provide the best conditions for mock orange shrubs. Shade can inhibit blooming and encourage leggy growth, which detracts from the appearance of otherwise healthy shrubs. Fast soil drainage is also key because boggy conditions can contribute to root problems. Plant in spring, amending the bed to a 12-inch depth with a 3-inch layer of compost to improve its texture. Space multiple mock orange shrubs according to their mature height. For instance, Belle Etoile mock oranges need 3 to 4 feet of space, while June Bride mock orange needs 4 to 6 feet.

Mock orange shrubs seldom need supplemental fertilizer, especially if their bed contains organically rich soil. However, a light application of organic fertilizer each spring can help those grown in leaner soil to produce a more spectacular flowering display. Use a blooming fertilizer with an N-P-K analysis of 12-4-8 or a general purpose, 10-10-10 fertilizer. Sprinkle 1/2 cup of 12-4-8 or 1 cup of 10-10-10 beneath the drip-line of the shrub and scratch it into the soil surface. Always apply fertilizer to moist soil, or water the fertilizer in immediately after applying it to prevent root burn.

Although moderately drought tolerant, mock orange shrubs appreciate regular watering during the growing season. One inch of water weekly is ideal, which is an amount that moistens the top 6 to 15 inches of soil, depending on the soil type. However, it is best to let the soil dry out in the top few inches between waterings to prevent root problems and fungal infections. A 3-inch layer of lightweight organic mulch around the base of each shrub -- but not touching the stems -- will help keep the soil moist for longer, which will decrease the frequency and depth of irrigation and help limit stress to the shrub.