Idaho’s Wine Geography
With a surfeit of maverick spirits, spare ground, and stubborn will, Idaho’s winegrowers and winemakers are fiercely proud of their vines, wines, and land. Long on ambition, this nascent wine community is building its knowledge base, attracting adventurous winemakers, and honing its craft in the steady belief that it can be the next great wine country.
Snake River Valley
The vast Snake River Plain extends like a sly half smile from the town of Ontario, just over the border in Oregon, down through Boise, Mountain Home, and Twin Falls at the southern end of the arc. From there the broad plain turns up toward the northeast through Pocatello and Idaho Falls. Along the upturned western portion of this arc, mostly on the well-drained benches and terraces neighboring the towns of Caldwell and Parma, the majority of Idaho’s vineyards are found.
There are some small vineyards and a few wineries in the northern panhandle section of the state. Usually, these wineries source grapes from nearby Washington, and their total production of Idaho-grown grapes is not significant, though the quality of their wines can be quite high.
Most of Idaho’s vineyards are between 2200 and 3000-ft., the highest vineyard elevations in the Northwest. At roughly 550 miles east of the Pacific Ocean, the climate of this high desert country is distinctively continental. Summers in Idaho’s wine counties are very warm (sustained temperatues above 100°F are common) and dry (mean annual precipitation can be 10-in. or less), winters very cold (multiple days below 0°F), and the growing season quite short. At elevations where vineyards are typically planted, the Snake River Valley delivers growing degree days ranging from 2600 to 3300—enough to ripen nearly any variety, and perhaps over-ripen many.
The Snake River Valley is part of the Columbia River drainage and was originally formed by geologic processes similar to those of eastern Washongton and Oregon—including its own ancient Lake Bonneville flood, a localized mini-versioon of the Missoula Flood. Backwashes of sediment, benches and terraces of gravel, and slack-water bars are present throughout the valley as remnants of the Bonneville Flood, forming the soils and terrain of today’s vineyards. So complex were these geologic activities that there is no dominant soil type within the AVA.
The short growing season and high daytime heat mean that proper site selection is critical for Idaho winegrowers. Though still relatively young in its viticultural development, winegrowers are increasingly learning which varieties grow best in which places, resulting in an ever-increasing level of wine quality.
Though there is no dominant grape variety or Idaho wine style, the short warm summers and cold nights are conducive to many white varieties. Riesling, in particular, has historically been a strong performer and is widely planted. Very dry and cool autumns give winegrowers the opportunity to let riesling hang on the vine long after the normal harvest, and Idaho has produced excellent late harvest wines as well as true frozen-on-the-vine ice wine. Increasingly, viognier is gaining a foothold, and more careful prioduction of chardonnay is proving promising.
Among red grapes, Idaho early chose the traditional Bordeaux varieties,emphasizing cabernet sauvignon and merlot. The region’s heat would seem good for these grapes, but the quite cold nights and short season tend to produce lean and tart styles. In more recent years Idaho has shown great potential for Rhône varieties, especially syrah.