Holodiscus

( hol - oh - DISK - us )

At-A-Glance Information

Holodiscus, commonly referred to as Ocean Spray, Ironwood, or Cream Bush is a genus of flowering deciduous shrubs that need partial shade and little to regular water. The flowers attract birds, bees and butterflies. This genus includes a variety of sizes of plants, from tall shrubs to groundcovers. Flowers are creamy white and form in clusters in late spring or early summer. They have a faint, sweet sugary scent, and look a bit puffy and billowy. Dried flower clusters remain on the shrub through wintertime. Bark is peeling and brown-ish, and branches arch gracefully outward. Plant these shrubs in woodland border gardens, against buildings, or at the back of a shrub bed.

Holodiscus Species and Varietals

The genus Discolor includes between 7 and 10 species and is a member of the plant family Rosaceae. The genus name Holodiscus means 'entire disc', referring to the unbroken cup that supports the petals, stamens, and sepals. The ideal growing zones for Holodiscus are USDA hardiness zones 5-10 and Sunset growing zones 1-9 and 14-19, though this sometimes will vary depending on the species. See the descriptions below for more information. To find your zone, click here: Zone Map.

Holodiscus discolor (Cream Bush, Ocean Spray, Ironwood, Oceanspray, Rockspirea)
This species is native to the Coast Ranges, Sierra Nevada up to British Columbia and east to the Rocky Mountains. This shrub can reach 20 feet tall and 15 feet wide in moist, nutrient-rich soil. Leaves are deep green on top and white and hairy underneath. Flower clusters can reach up to a foot long, blooming from May through July.

Holodiscus microphyllus (Rock Spiraea, Small-Leaved Cream Bush, Small-Leaved Ocean Spray, Bush Ocean Spray, Small Leaf Mountain Cream Bush)
This small shrub is native to high elevations in western North America. It spreads to form a mat of dark leaves with 3 inch flower clusters. Individual plants in this species reach up to 1.5 to 3 feet tall and 2 to 6 feet wide at maturity. Use Rock Spiraea as a groundcover or in a rock garden.

Caring for Holodiscus

Holodiscus shrubs are considered easy to care for, and are a part of the natural landscape in many Western gardens. Plant these shrubs in a space in the landscape that receives full sun to partial shade; ideally, they appreciate between 6 and 8 hours of sun each day for the best blooms. They appreciate some afternoon shade in warmer climates. Ensure that soil is well-draining, rich in nutrients, and has a pH of between 5.0 and 7.5 (slightly 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 plants are considered somewhat drought-tolerant, able to get by for much of the year on rainwater alone with supplemental waterings during extended periods of dry weather. During their active growth and flowering seasons in spring and summertime, they appreciate consistently moist soil.

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. Pruning is simple; remove any damaged, diseased, or dead foliage at any time during the growing season, and remove spent flower spikes to neaten up the appearance of plants and encourage reblooms. The best time to do a rejuvenation, shaping, or general pruning is in the late summer to early fall after flowers have faded. These shrubs bloom on old wood. Holodiscus shrubs are considered long-lived perennials and are able to survive in the landscape for a few decades (between 10 and 30 years) before needing to be replaced.

Propagation

Holodiscus can be propagated either by using cuttings or from seed. To ensure that your propagated plant will have the exact same qualities and characteristics as the parent plant, use the cutting method. If you would like to experiment and see what plant you can grow from seed, just keep in mind that it will not necessarily be the same as the parent plant. To propagate your shrub, follow the instructions below:

Propagating Holodiscus 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. A good substrate for propagation of cuttings is a light blend of 1/3 pasteurized soil or compost, 1/3 sand, vermiculite or perlite, and 1/3 coconut coir or peat moss.
In spring or early summertime, 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 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.

Propagating Holodiscus by Seed

Keep in mind that the plant you get from seed will not necessarily mimic all of the characteristics of the parent plant. To propagate by seed, you will need a paper bag, a pot or tray filled with well-draining compost or other organic material, a spray bottle and a fork. The best potting medium for seed germination is a light blend of 1/3 pasteurized soil or compost, 1/3 sand, vermiculite or perlite, and 1/3 coconut coir or peat moss.
Harvest your seeds in fall, when the seed pods have turned dry and brown.
Holodiscus seeds need to be cold-stratified before sowing. Place your seeds in a moistened peat moss bed inside of a plastic, sealable bag and place the bag in the refrigerator (at about 40 degrees Fahrenheit) for 120 days.
Water your prepared seed tray or pot filled with soil, and ensure that good drainage is occurring. Place your seeds in your prepared pot or seed tray about a quarter inch to a half-inch under the soil surface. Cover them with soil and water with your spray bottle. Place your tray of seeds in a warm area that receives bright, indirect light. A greenhouse is the most ideal climate, but a planting tray inside a window will do as well. Germination usually takes 7-14 days from sowing. Once you begin to see seedlings sprout and they are able to be handled, transplant them to their own individual 3-inch pots, filled with the same potting medium as described in Step 1. Loosen the seedlings from the potting medium by digging down with the tines of your fork about an inch and a half, gently working the seedling up until it is out. Then, replant the seedling in its individual pot.
Keep the seedling's potting medium moist, but not wet, by spraying the soil with your spray bottle. 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 (after the danger of frost has passed), when you can transplant it to its new home.