Oceanspray, also known as cream bush rock spirea, ironwood or arrowwood is a common native flowering shrub found growing in forests on the Southern Gulf Islands and Vancouver Island. In logged areas, or forests recovering from wildfire, it may be one of the first plants to appear. In July, we can identify oceanspray by its large clusters of small white flowers.
Oceanspray is in the rose family along with laurels, apples, cherries, and peaches! The leaves are triangular with small rows of scallops or lobes along the edge, resembling those of the black hawthorn tree, although oceanspray leaves are dull and hairy rather than glossy. The gorgeous creamy white flowers that appear in July make a notable display in early summer, attracting pollinators such as butterflies and bees.
The multi-stemmed growth habit of oceanspray makes it an excellent choice for hedges. It is deciduous however, so provides less privacy in the winter. Oceanspray grows to a height of ten to fifteen feet (3 to 3-4.5m) and is equally wide when protected from deer browse. In locations where they are subject to deer browse, all new shoots are eaten, giving most remaining plants on Mayne Island a distinctive umbrella shape, and preventing new plants from establishing. Younger plants on Mayne are browsed so heavily they often look more like a ground cover plant. Oceanspray is drought tolerant once established and is an excellent choice for a sunny or semi-shaded woodland garden, at the back of a shrub bed, or next to a building.
Oceanspray is valuable as a pollinator plant for native bees and butterflies and as a host for various caterpillars including the Lorquin’s admiral and the pale tiger swallowtail. The canopy provides good cover for birds, small mammals, and amphibians, such as the pacific chorus frog.
In nature, wind and animals often disperse the oceanspray seeds, which can be collected in early August. If you chill (stratify) the seeds at 4ºC (40ºF) for 3 to 4 months, they will germinate easily. Alternatively, you can sow the seeds in an outside bed in the fall and allow them to stratify naturally. You can also propagate them by hardwood cutting, layering or root division. It will readily sprout from the root crown after fire or clearing removes the top growth. The Mayne Island Conservancy grows this species successfully from seed, and we find it takes two growing seasons to produce a 30cm plant in a one-gallon pot. We recommend watering newly planted shrubs in the summer for the first two years after planting. Once established they grow very quickly and if desired, can be maintained at a smaller size by pruning out the oldest stems at the base of the plant each year.
The common name ironwood reflects the character and strength of its stems. First Nations would heat the wood over a fire to increase its hardness before polishing it with horsetail stems. They would then make it into spears, harpoon shafts, bows, arrows, and sticks for digging. The Saanich and Cowichan peoples used it to make construction fasteners, barbeque and scraping sticks, halibut hooks – and more recently, knitting needles. They also made tea from the small hairy fruit to treat diarrhoea, measles and chickenpox, and a poultice from the leaves.