Stroll 16 acres of outdoor gardens, including a 2-acre Rose Garden showcasing hardy shrub varieties inspired by Wisconsin native Frank Lloyd Wright's Prairie style. Other outdoor gardens at Madison's Olbrich Botanical Garden include a Perennial Garden, a Sunken Garden and an Herb Garden. Be sure to see the Thai Pavilion, crafted without nails or screws by Thai artisans. Also, the Bolz Conservatory features exotic plants, flowers, orchids, birds and a waterfall. Special events include a popular summer butterfly show.
More than 75 acres of formal gardens, greenhouses and woodlands flourish in the heart of the city. Visit the Japanese strolling garden, one of the largest in the Western Hemisphere. In the new Children's Garden, kids can scramble through a tree house and play in water jets. The glass art of Dale Chihuly is on display in three installations, including the seasonal Walla Walla Onions (pictured) in the central reflecting pools. Come early in the morning and you'll have the Missouri Botanical Garden nearly to yourself, save for a few amateur photographers.
An outdoor plant museum, the 385-acre Chicago Botanic Garden in Chicago's northern suburb of Glencoe features 24 display gardens set like flowering jewels among lakes, prairie and woodlands settings. Visitors can observe plant scientists conduct research and work on conservation and environmental projects in the Daniel F. and Ada L. Plant Conservation Science Center. Special events are held year-round, including flower shows, farmers markets, cooking seminars, literary programs, art fairs and concerts. Chicago Botanic Garden 
More than 20 miles of trails wind through the gardens of the 3,600-acre Holden Arboretum in Kirtland, 23 miles northeast of Cleveland. Among the highlights: the 20-acre Helen S. Layer Rhododendron Garden, where some of the 500-plus cultivated varieties are nearly 60 years old. Late May is the time to visit for peak rhodo bloom. Other areas of the arboretum include a butterfly garden, wildflower garden and conifer collection. The Holden Arboretum 
Trails and lush gardens along the U.S.-Canada border celebrate peace between the two nations. The 2,300-acre garden, about 110 miles northeast of Minot, is half in the U.S. and half in Canada. In summer, the International Peace Garden gets big splashes of color from perennials and annuals; for the best blooms, visit in July or August. For visitors year-round, a new Interpretive Center offers a restaurant, gift shop and conservatory with 3,000 cacti. Guided tours of the gardens are available by reservation.
Two miles of paths wind through formal gardens, a wildflower meadow and an arboretum with wild turkeys at Lauritzen Gardens, along the Missouri River Valley south of downtown Omaha. Tour more than a dozen gardens, including an herb garden, children's garden and rose garden. Tram tours are available.
There's something beautiful to see here every season of the year; one of our favorite annual events is the Poinsettia Show, which starts in late November and runs through early January. Thousands of poinsettias -- in shades of red, pink, white and variegations -- flare against indoor gardens' tropical foliage.
Lauritzen Gardens 
A world-class sculpture collection scatters among the blooms at Frederik Meijer Garden and Sculpture Park. The gardens on the northeast side of Grand Rapids fill a towering glass conservatory and 132 acres, while the sculpture collection is housed in both an indoor gallery and a 35-acre outdoor display. Don't miss the exceptional children's garden, with elevated tree house paths, a sense garden and a model of the Great Lakes, complete with toy boats.
More than two dozen themed gardens spread over 9 acres at Botanica, The Wichita Gardens, showcasing 3,600 species of plants. Sculptures, fountains, waterfalls and streams dot the grounds. Among the areas to explore: the Butterfly Garden, Woodland Walk, Garden on the Rocks, Sally Stone Sensory Garden and the Jayne Milburn Aquatic Collection.
Roses, woodland wildflowers, water and shade gardens, and hostas flourish on 52 acres - the only public garden in the nation operated solely by volunteers. The Dubuque Arboretum and Botanical Gardens is known for its hostas, with 13,000 plants and 700 varieties. Special events include concerts on summer Sundays.
Ten acres of gardens and an 18,000-square-foot glass conservatory feature a large collection of both native and exotic plants. The Cleveland Botanical Garden's Glasshouse spotlights plants, insects, birds and more from the spiny desert of Madagascar and the rainforest of Costa Rica. Kids will love exploring the giant tree house, maze and other activities in the Hershey Children's Garden.
Tucked in a busy commercial area, the Green Bay Botanical Garden offers a welcome oasis of 47 acres of gardens and natural areas. Winding paths take visitors through themed areas, including rose gardens, color gardens, perennial gardens, an English cottage garden, a Wisconsin woodland garden and the new King Shade Garden. The Children's Garden includes a maze, sensory garden and an area with nature-theme puzzles. Check the website for special events throughout the year, including summer concerts.
As the first public university established west of the Mississippi, Mizzou has a distinctly historic feel, with 18 buildings on the National Register of Historic Places. The grounds are also a designated botanic garden, with more than 6,500 trees, themed gardens and special-collections gardens. The Reynolds Alumni Center offers maps for self-guided tours of Mizzou Botanic Garden; free guided tours are available for groups.
The 105-acre Fernwood Botanical Garden and Nature Preserve near the southwest Michigan town of Niles (90 minutes east of Chicago) features extensive gardens, an arboretum and tall grass prairie in the St. Joseph River valley. Specialty areas include a Japanese dry garden, ravine garden, Herb and Sensory Garden, wetlands, hosta collection, rock garden and lily pond. Trails wind through the gardens, a 5-acre prairie reconstruction and 55-acre nature preserve. Check the website for nature classes, concerts and other programs.
This 880-acre preserve sits along the Cannon River and is adjacent to Carleton College in Northfield. Fifteen miles of trails lead through the woods and prairie at the preserve and attract walkers, joggers and bikers (as well as cross-country skiers in winter). Bird and wildlife watching is popular at Cowling Arboretum. Spring brings an impressive display of spring wildflowers.
Cowling Arboretum 
The highlight of the 915-acre Powell Gardens is the Heartland Harvest Garden, which celebrates Midwest agriculture with some 2,000 varieties of fruits and vegetables planted on 12 scenic acres outside Kansas City. It's considered the largest edible garden in the country. Visitors can sample seasonal produce at tasting stations in the garden or in salads, wraps and soups at the cafe. A Fun Foods Farm offers hands-on education for kids.
Powell Gardens also features a 3.25-mile nature trail past ponds, through woods and along a creek; a fountain garden; and a 2-acre memorial garden.
Powell Gardens 
The sprawling 1,700-acre Morton Arboretum in Lisle (25 miles west of Chicago) includes 500 acres of plant collections and gardens as well as 900 acres of woodlands, prairies, lakes and streams. Depending on the season, visitors can explore by hiking, biking, running, skiing or snowshoeing. If you're visiting with kids, be sure to see the 4-acre Children's Garden, with hands-on nature activities and exploration areas such as the Wonder Pond (pictured). The arboretum hosts special events throughout the year; check the website for information on guided walks, concerts, art shows and seasonal festivals.
Morton Arboretum 
One of the country's prettiest zoos boasts 85 acres of flower-fringed exhibits. More than 500 animals live here, but it's the gorgeous landscaping -- especially during spring tulip season -- that makes the Cincinnati Zoo and Botanical Garden a pleasure for adults as well as children. Take a stroll around the picturesque Swan Lake, and hop on a train to get a good overall picture of the beautiful landscape. The Duke Energy Go Green Garden offers great lessons about green energy -- and has a cool mosaic made from trash.