Pacific Coast Iris: low maintenance wildflowers

Written October 12, 2012, published November 2012

A showy group of irises are native to the West Coast from southern California to southwestern Washington. Called the Pacific Coast Iris (PCI), these species grow very well in our area. There are thirteen to fourteen species and hundreds of hybrids. PCI grow in well-drained soils with some compost and mulch, and prefer part sun to full sun along the coast. Otherwise they need little summer care. They flower from March to June, with peak bloom in May-June. In my garden, they peak just as the lilies start, so I have a continual blooming sequence from March to September, first of iris, then of lilies. The genus Iris is large, with more than one thousand species and many sections. The most well known Iris section is tall bearded (TBI), which are big plants with large rhizomes, very tough, and which grow well in humid wet conditions. The term “bearded” refers to tufts of hairs on the “falls,” the three large petals that hang down in each flower. The upright petals are called standards. There are more than a dozen sections of Iris in the non-bearded group, and PCI are one of those sections. 

PCI Rodeo Gulch, a registered orange with purple signal, from BayView Nursery, Santa Cruz, CA. Photo by Kathleen Sayce

The big yellow TBI that grows along the Columbia River is Iris pseudacorus, yellow flag, from Europe. Yellow flag is listed as a noxious weed in several states, and thrives in wetlands. 

PCI flowers are slightly smaller than TBI flowers; PCI plants are shorter with long, narrow evergreen leaves instead of wide leaves. One species is deciduous, Iris tenax, which lives in southwestern Washington and western Oregon. Plants range in height from less than ten inches to around thirty inches tall. 

PCI Cape Sebastian, an unregistered selection with white flowers and a very showy purple and gold signal. Photo by Kathleen Sayce 

PCI flower color range is wide, from white thru pink, rose, red, orange, yellow, lavenders, blues and purples, browns, to nearly black, which is seen in some very dark red and dark purple flowers. There are hybrids with showy signals (spots on the falls or lower petals), veining, halos, and ruffling. There are wide petal forms and narrow petal forms, bicolor and bi-tone forms. 

PCI Mission Santa Cruz, a lovely rich red-purple flower on a sturdy plant.  Photo by Kathleen Sayce 

Unlike bearded iris, PCI are not wetland plants and do not need much summer water. PCI tolerate wet winters and dry summers; in other words, our normal rainfall patterns are fine for them. They like mildly acidic soils, which is our normal soil condition. A little compost and mulch helps them in sand or clay soils, a little fertilizer promotes flowering. PCI also do well in meadows, where they thrive with an annual fall mowing, which is essential in our climate to keep woody shrubs and trees from growing into grasslands. Native bees, ants and hummingbirds visit PCI flowers, which provide both nectar and pollen. A few are mildly fragrant. 

I have not had deer, aphid, caterpillar, or disease problems in my garden, except when I first planted them. Deer tugged up, chewed on, and spit out all the PCI seedlings the night after they were planted. I found the seedlings the next day lying on the ground, somewhat battered from chewing. I put them back in the ground, and half of them lived. Since then, the deer leave them alone, except for an experimental mouthful every year or so by a fawn that is learning food plants for the first time.  

PCI Blue Plate Special, a registered blue from BayView Nursery, Santa Cruz, CA. Photo by Kathleen Sayce

I started growing PCI more than a decade ago, when I was first practicing dry gardening, and soon learned why PCI aren’t more widely grown: They can be successfully transplanted only for a few weeks in spring, and for a couple of months in fall. I move PCI in the fall, from late September to November, after waiting for wet weather to start, and typically water them only once, the day they are planted. Now I have six species and several dozen hybrids in my garden. Among irisarians, this is barely getting started; I know urban gardeners who grow more than 1,000 iris varieties on a city lot.  Every three or four years they should be divided; if I can’t get to my plants then, I give them more compost to tide them over. 

PCI Finger Painting, a registered blue and white form, from BayView Nursery, Santa Cruz, CA. Photo by Kathleen Sayce

Unlike bearded iris, PCI do not like to sit in hot containers in summer, with hot roots, or to lie on the ground for weeks waiting to be planted. They do not like soggy wet feet in summer, either, or hot humid weather; the latter keeps them from being grown in much of central to southeastern US. 

PCI Joy Creek Orchid, an unregistered selection from Joy Creek Nursery, Scappose, OR, with an orchid flower, and a multicolored signal on the falls. Photo by Kathleen Sayce

Out here on the Pacific Northwest Coast, PCI thrive in all but wetland soils, and in part sun to full sun, even in bright shade. My garden has silty sand with some compost mixed into the soil and mulch on top, and here they grow very well.  One species grows only along the immediate coast from southern Oregon to southern California, Douglas iris, Iris douglasiana. It thrives in salty, windy coastal soils, on sand and on seacliffs. Locally, Douglas iris grows in the Discovery Garden at Columbia-Pacific Heritage Museum, Ilwaco, Washington. These plants are typical: tall, with pale lavender to white flowers with a yellow signal, and usually flower in May-June. 

PCI Cape Ferrelo, a light blue form of Iris douglasiana, photo by Kathleen Sayce

With a huge range of PCI sizes, colors, and forms to chose from, there is a PCI for you, just waiting for a chance to grow in your yard. For more information, take a look at  HYPERLINK "http://www.pacificcoastiris.org" www.pacificcoastiris.org, the website for the Society for Pacific Coast Native Iris.  The society maintains the registry of hybrid PCI. Pages on each registered hybrid are posted in the American Iris Society’s Iris Encyclopedia, at  HYPERLINK "http://wiki.irises.org/bin/view" 
http://wiki.irises.org/bin/view in the PCN section. 

You can also find information about all the other sections of iris on the AIS website.  

Iris douglasiana, Douglas iris, Columbia Pacific Heritage Museum, Ilwaco, WA, a very pale lavender to white flower with a yellow signal on the falls. Photo by Kathleen Sayce.