Wild native shrub suitable for home landscapes

Hoping for an alternative to the common landscaping plant Japanese Spirea, Purdue University scientist Mike Mickelbart found that it's possible to bring the plant's native cousins into backyards.

Mickelbart, an associate professor of horticulture, has filled his yard with native plant species. Spiraea japonica, a shrub also known as Japanese Spirea that typically has pink flowers, is one of the most common landscape native species available at nurseries, but Mickelbart has never been attracted to it.

"Planting natives in my backyard is a fun way to learn about the native flora," Mickelbart said. "I see a lot of Spiraea japonica and day lilies. But I would like to see the palette of native plants available for landscape use expand."

Spiraea alba, a shrub with white flowers, and Spiraea tomentosa, a shrub with pink flowers, are native to much of the Midwest and Northeast in the United States. But the acidic soils the shrubs are used to in their wild habitats were seen as limiting factors in adapting the plants to urban Midwestern landscapes, which typically have neutral to alkaline soils.

Top: S. alba. Bottom: S. tomentosa.

Mickelbart grew the plants over two years in a range of soil pH levels - from the acidic soil the plants are used to in the wild, to a neutral soil common in home flower beds. The neutral soil pH levels resulted in slightly smaller plants than would be found in natural settings, but leaf greenness and leaf size were unaffected.

"These are underutilized native plants," said Mickelbart, whose findings were reported in the July issue of the journal HortScience. "This shows that they could be incorporated into our landscaping. They might be a little smaller, but they should do just fine."

The drawback, Mickelbart said, is that local nurseries don't currently carry Spiraea alba and Spiraea tomentosa. He said that anyone interested should look to online seed or plant dealers, or ask a local nursery if they can obtain plants.

"These plants are not out there yet, but if demand grows, nurseries might start carrying them," Mickelbart said.