Rustler Gulch, CO 8 miles (Moderate)
Dense fields of flowers–more than 100 species–electrify the meadows of Rustler Gulch and make this the premier petal hike near Crested Butte, itself the unchallenged wildflower capital of Colorado. The round-trip starts off by meandering through aspens and evergreens where monkshood and cow parsnip bloom. After a moderate ascent, the route spills out of the trees into a rainbow of flowers surrounded by jagged pink peaks. The pièce de résistance: an 11,400-foot-high alpine cirque blue with columbines. You’ll need an early start to beat the crowds in prime time (late July), but it’s worth it.
Info (970) 641-0471
Siyeh Pass, MT 10.3 miles (Moderate)
If there weren’t fields of wildflowers, this one-way hike in Glacier National Park would still deliver some of the most stunningly chiseled scenery in the Rockies, with close-up vistas of Mt. Siyeh and Sexton Glacier. Factor in the profusion of blooms that flourishes here starting in July, and it’s a life-list day in the mountains. Hike through Preston Park’s smorgasbord of petals, cross 8,080-foot Siyeh Pass and a sea of yellow glacier lilies, then descend 3,440 feet to Sunrift Gorge (where you can catch a free shuttle back to the trailhead in July and August).
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Fox Creek Pass, WY 18.4 miles (Difficult)
If you think wildflower hikes always end too soon, this is your dream trail. Allow all day–and pack a headlamp just in case–on this round-trip in Grand Teton National Park. The route up Death Canyon to Fox Creek Pass climbs 3,100 feet and serves up wildflowers the entire way. It crescendoes in a bloom lover’s nirvana just below the pass, at nearly 10,000 feet, where shoulder-high purple asters and a Technicolor mix of petals crowd the meadows (late July is usually the best). Then descend along Death Canyon Creek, where bluebells cluster in the shade and golden asters explode on sunny slopes.