Native Plants for Idaho

Idaho is long, and its two ends are barely related. The northern panhandle catches enough Pacific moisture to support an inland temperate rainforest: western red cedar, western hemlock, and an understory of ferns and moisture-loving plants that are otherwise a coastal community. It is a disjunct occurrence, cut off from the coastal forests by the dry country between.

Southern Idaho is the Snake River Plain, a broad arc of volcanic ground running across the state, arid and covered historically by sagebrush steppe. Precipitation there is low, and irrigation is what makes the agriculture possible.

Between and around them, the central mountains are extensive, rugged, and high, with montane and subalpine conditions and some of the largest roadless country in the lower forty-eight.

Sagebrush steppe, and its trouble

The sagebrush steppe of southern Idaho is the state's most extensive habitat and one of its most altered. Invasive annual grasses have spread through much of it, and because they dry early and burn readily, they have shortened fire cycles beyond what native shrubs can survive. Sagebrush does not resprout after fire and recovers slowly, so repeated burning converts steppe to annual grassland.

Planting native steppe species in a home garden will not fix that, but it is worth understanding why sagebrush, bitterbrush, and the native bunchgrasses are worth keeping and why restoration seed is in demand.

For gardens, the steppe palette suits dry, sunny, alkaline sites: bluebunch wheatgrass, Idaho fescue, lupines, penstemons, buckwheats, and arrowleaf balsamroot, which is among the most striking spring plants in the interior West.

Volcanic ground and elevation

Southern Idaho soils are often derived from volcanic rock and lava, shallow in places, and generally alkaline. Northern soils are different, more acidic under the conifer forest.

Elevation ranges enormously, and hardiness follows it. Determine your elevation and aspect before choosing plants; a north-facing mountain site and a south-facing valley site are different worlds.

Timing

In the dry south, fall planting takes advantage of winter moisture to establish roots before the summer drought. In the wetter north and at elevation, spring is generally safer.

Water new plantings through the first season and then step back, since steppe species decline under summer irrigation.

Confirming what is native to your county

The Idaho Native Plant Society runs chapters across the state's very different regions, and the Idaho Department of Fish and Game documents natural communities and species distribution. University of Idaho Extension publishes regional guidance.

Sources: Idaho Department of Fish and Game, Idaho Natural Heritage Program (natural communities and species distribution); University of Idaho Extension (regional guidance); USDA PLANTS Database (native status by state).