Most folks think of Zinnias, as an annual bedding plant, but the genus actually includes so much more, including some little-known, North American native perennials. One that has thrived for us, since 2018 is Rocky Mountain zinnia, Zinnia grandiflora, which naturally resides from Kansas to Arizona. We’re growing a particularly vigorous selection, Zinnia grandiflora ‘Gold on Blue’, discovered by the late nurseryman, David Salman at 6,000′ elevation in Southern Colorado. In the garden, it needs extremely dry, preferably alkaline soils, and bright sun, which is why it resides in our crevice garden in alkaline gravel. The bright yellow flowers start in mid-summer and continue into fall, as you can see by the photo below, taken this week. Hardiness Zone 4a-8a.
