From Mother Nature Network's Tom Oder:

Where are the world’s best botanical gardens, the ones that should be on the bucket list of everyone who loves plants?

We thought our favorites and then we asked some experts — horticulturalists and administrators at a botanical garden in the United States (and for the record, none of them nominated their own gardens), a nursery owner on the West Coast of the United States, the president of a U.S.-based floral group with an international membership, and a garden writer and editor in Scotland. We also talked to a few plant geeks.

From their answers, we compiled this list of 13 below.

Several suggested that we include a few public gardens because their collections are so outstanding in terms of presentation, diversity, rarity, historical significance or conservation of endangered species that they deserve to be included. We considered several.

Finally, we came up with the list below — a baker’s dozen of botanical and public gardens around the world that should be on the must-see list of gardeners before they die. Eight are in the United States. The others are in Africa, Asia, Canada, Europe and the United Kingdom.

Our list is subjective — of course. We know that. We may have even left off one of your favorites. What gardens are on your list and why?

We’ve planted the seed. Now, let the discussion flower in the comment section below!

List and captions courtesy of Mother Nature Network

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  • Atlanta Botanical Garden, Atlanta, GA

    <strong>Worth a visit because:</strong> It has the largest collection of species orchids under glass in the United States. <strong>Description:</strong> The Atlanta Botanical Garden's large and diverse collection of orchids includes specimens from Asia, Australia, Central America, Mexico, Ecuador and Madagascar. The plants are displayed in landscaped areas and seasonal displays in three main growing spaces in the 16,000-square-foot Fuqua Orchid Center: The Orchid Atrium, a space for events and changing seasonal displays; the Display House, which bursts with the color of tropical species; and a Tropical High Elevation House, where mist shrouds cloud forest orchids. The garden makes its extensive library available to researchers by appointment and is a leader in orchid conservation efforts, especially with the propagation and re-establishment of the cigar orchid (Cyrtopodium punctatum) in Florida and the monkey face orchid (Platanthera integrilabia) in Georgia. <strong>Best time to visit:</strong> February-April, when the annual Orchid Daze exhibition showcases thousands of orchids in bloom. This late-winter, early-spring time frame also overlaps the March-April Atlanta Blooms festival when several hundreds of thousands of daffodils, tulips and other spring bulbs are in flower. <strong>While there, be sure to see:</strong> Canopy Walk, a 300-foot-long elevated walkway 45 feet high through the canopies of some of Atlanta's oldest hardwoods. <strong>Website: </strong><a href="" target="_hplink">Atlanta Botanical Garden</a>

  • Chanticleer, Wayne, PA

    <strong>Worth a visit because:</strong> It has been called the most romantic, imaginative and exciting public garden in America. <strong>Description:</strong> While technically a public pleasure garden rather than a botanical garden, Chanticleer made our list not only because of the great diversity of the 5,000-plus plants in the 35 acres of various garden styles, designs and combinations, but also because the staff takes its educational responsibilities seriously. Visitors are encouraged to ask the gardeners questions, study the garden designs and borrow ideas to use in their own gardens. One of the most popular Chanticleer gardens is the Asian Woodland Garden, which originally was a tangled area of poison ivy and honeysuckle. It was cleared and replanted with plants such as gingers, primulas and Jack-in-the-pulpits native to Korea, Japan and China, but the design style is of a shady American woodland garden. <strong>While there, be sure to see:</strong> The new Bell's Woodland Garden that celebrates plants of the eastern North American forest. This garden opened in April 2012 and is still being planted. The main path wanders through azaleas, foam flowers, ferns and other woodland plants. <strong>Best time to visit:</strong> Spring. (The garden is closed November through March.) <strong>Website:</strong> <a href="" target="_hplink">Chanticleer</a>

  • Denver Botanic Gardens, Denver, CO

    <strong>Worth a visit because:</strong> This internationally acclaimed garden is a premier example of the art of rock gardening. <strong>Description: </strong>There are more than 500 tons of rock and 2,300 species of plants in the garden. The rock placements provide habitats similar to more than a dozen different environments based on slope, soil type, moisture and exposure and serve as a testing ground for many uncommon Southwestern plants. The Alpine plant collection recently achieved national status and is now part of the North American Plant Collections Consortium. Succulent collections can be seen in the Dryland Mesa and include cacti, yucca and other xeric plants. The garden does not get any supplemental watering except during severe drought. Another garden showcasing xeric plants with limited watering is the WaterSmart Garden. <strong>Best time to visit: </strong>The peak flowering time is between May and October, but there is something of interest at Denver Botanic Gardens during every season. <strong>While there, be sure to see:</strong> The newest addition -- The Bill Hosokawa Bonsai Pavilion and Tea Garden. The Mordecai Children's Garden, the Boettcher Tropical Conservatory, Marnie's Pavilion and the Orangery are also popular with visitors. <strong>Website: </strong><a href="" target="_hplink">Denver Botanic Gardens</a>

  • Desert Botanical Gardens, Phoenix, AZ

    <strong>Worth a visit because:</strong> It features the nation's largest collection of arid-adapted plants that focus on the Sonoran Desert. <strong>Description: </strong>The Desert Botanical Garden collection of more than 4,000 species and approximately 17,000 individual plants includes giant cacti, century plants and many other rare and unusual plants from the Sonoran Desert, which covers large parts of the Southwestern United States in Arizona and California and Northwest Mexico. In 2010, the garden's living collections of plants in the cactus and agave families were designated as National Collections of these plants by the North American Plant Collections Consortium of the American Public Gardens Association. The displays also feature plants native to other arid regions around the world. <strong>Best time to visit: </strong>March-May when the desert wildflowers, most cacti and other plants in the displays are in bloom. <strong>While there, be sure to see: </strong>The Plants and People of the Sonoran Desert Trail to learn how native peoples thrived in the desert, and the Center for Desert Living Trail to explore sustainable living in the herb and edible gardens. <strong>Website:</strong> <a href="" target="_hplink">Desert Botanical Garden</a>

  • Fairchild Tropical Botanic Garden, Coral Gables, FL

    <strong>Worth a visit because: </strong>Of its world-class palm collection showcased in a historic landscape setting. <strong>Description:</strong> Fairchild Tropical Botanic Garden can be enjoyed in several ways. For the casual gardener, there is the aesthetic beauty of taxonomically arranged and well-documented tropical plants -- especially palms, cycads, flowering trees and shrubs, vines and fruit trees -- showcased in a classic landscape design by William Lyman Phillips. Many visitors find the experience unforgettable. For the more serious plant enthusiast, these documented botanical specimens, which have been collected or cultivated since 1938, are a resource of world significance for science and education. <strong>Best time to visit: </strong>Something's always blooming at Fairchild. Whether it's flowering trees, flowering vines, orchids or exotic plants, it's always a good time to visit this tropical paradise. <strong>While there, be sure to see:</strong> The two-acre Richard H. Simmons tropical rain forest and the Lisa D. Anness Butterfly Garden. <strong>Website</strong>: <a href="" target="_hplink">Fairchild Tropical Botanic Garden</a>

  • Ganna Walska Lotusland, Santa Barbara, CA

    <strong>Worth a visit because:</strong> Of the bold forms and unusual color combinations of subtropical and tropical plants from around the world. <strong>Description: </strong>The garden's creator, Polish opera singer Madame Ganna Walska, turned plant collection into an art form. Experimenting freely with shape, color and design, she displayed her treasures in a series of gardens that draw the visitor from one surprise to another. The 37-acre botanical wonder she created contains additional gardens that feature ferns, aloes, succulents, lotuses, water lilies and bromeliads. Theme gardens include the blue garden, theatre garden, butterfly garden and a Japanese garden. Other classic features of Lotusland are the water stairs, the topiary garden, a horticultural clock, the Neptune fountain, a parterre and hedge allées. The garden also has an educational component, the Fourth Grade Outreach Program, which serves every fourth grader in south Santa Barbara County. Lectures and workshops are offered throughout the year. <strong>Best time to visit:</strong> The garden is wonderful all year long, but if you have a favorite plant group be aware before scheduling a trip that the namesake lotuses bloom in summer and the aloes flower in winter (aloes pictured above). The cacti bloom throughout the year. Lotusland offers docent-guided tours only. They are at 10 a.m. and 1:30 p.m. Wednesday through Saturday between Feb. 15 and Nov. 15. Advance reservations are required. <strong>While there, be sure to see:</strong> Hmmmmmm. Even the docents have a hard time choosing. Many people love the Japanese garden, the cactus garden is spectacular, and the water garden is lovely, particularly in the summer. <strong>Website:</strong> <a href="" target="_hplink">Ganna Walska Lotusland</a>

  • Longwood Gardens, Kennett Square, PA

    <strong>Worth a visit because: </strong>The gardens are considered to be one of the world's great horticultural displays. <strong>Description: </strong>The grounds encompass 1,077 acres of gardens, woodlands, meadows, fountains and a 4.5-acre conservatory -- the largest conservatory in the United States. Longwood is open every day of the year -- including all holidays! -- and is known for its extraordinary seasonal displays that offer a memorable experience for each visit regardless of the time of year. Longwood is also a leader in plant exploration, research and environmental stewardship, including the recent installation of a 10-acre solar field. <strong>Best time to visit:</strong> Spring and summer are glorious times to visit because that's when the 20 outdoor gardens and 20 indoor gardens are in their full splendor. That's also the time when Longwood's fountains (the gardens have more fountains than any garden in the United States) jet to life. Interestingly, the garden's busiest time is the Thanksgiving-to-mid-January holiday season when A Longwood Christmas display delights seasonal guests. <strong>While there, be sure to see: </strong>The Orchid Room in the Conservatory. Longwood's founder, Pierre S. du Pont and his wife, Alice, were founding members of the American Orchid Society, and Longwood boasts an orchid collection of more than 9,000 plants. <strong>While there, take a side trip to: </strong>As many of the more than 30 other public gardens in the region that have given the Philadelphia area the title of "Garden Capital of the U.S." <strong>Websites:</strong> -- <a href="" target="_hplink">Longwood Gardens</a> -- <a href="" target="_hplink">Complete list and description of gardens in the region</a>

  • New York Botanical Garden, New York City

    <strong>Worth a visit because:</strong> It is generally considered to be America's premier urban garden. <strong>Description: </strong>The New York Botanical Garden's living collections are an unforgettable departure from the everyday garden experience because they represent a "museum" of the plant kingdom. Plants in the collections are arranged in 50 gardens and landscapes across the garden's National Historic Landmark site in the Bronx. The highlights include the Haupt Conservatory, a Victorian-era style "crystal-palace" greenhouse; the Peggy Rockefeller Rose Garden; a rock garden; a 37-acre conifer collection; and extensive research facilities including a propagation center, a 550,000-volume library and an herbarium of more than 7 million botanical specimens dating back more than three centuries. <strong>Best time to visit:</strong> The garden is open year-round. Its special exhibitions, seasonal programs and engaging activities, both indoors and out, inspire visitors of every age and interest and offer plenty for them to see and do in every season. <strong>While there, be sure to see: </strong>The 50 acres of old-growth forest that are at the heart of the garden. This is the largest remnant of the original forest which covered all of New York City before the arrival of European settlers in the 17th century. <strong>Website: </strong><a href="" target="_hplink">New York Botanical Garden</a>

  • Walter Sisulu National Botanical Garden, Gauteng, South Africa

    <strong>Worth a visit because: </strong>Of the diversity of the magnificent and colorful flora of South Africa and the birds the flora attracts. <strong>Description:</strong> The Witpoortjie Falls are the centerpiece and backdrop to the Botanical Garden, which is located in one of the most biologically diverse areas of the world. The gardens include a succulent rockery garden, cycad garden, water garden, fern trail, arboretum, Geological Garden, People's Plant Garden, Birds and Butterfly Garden, Dell section, Waterwise garden, Children Garden, wild flower area, visitors' information center, restaurant and function venue. <strong>Best time to visit:</strong> It may depend on what season you like best. The garden is in flower in every season. The garden is at its best, though, during late spring and summer when most of the flowering shrubs come into bloom. In spring (September-November in the Southern Hemisphere) the red tubular flowers of the common coral trees (Erythrina lysistemon) attract numerous nectar-feeding birds, migrant swallows and cuckoos return, and the shade-loving bush lily (Clivia miniata) produces large heads of striking orange flowers. In summer (December-February) the unusual brick-red flowers of Pride-of-De-Kaap (Bauhinia galpinii), the mauve blue flowers of the wild phlox (Jamesbrittenia grandiflora and Dissotis sp.), and river lilies such as the scarlet red flowers of Hesperantha coccinea are a delight for weeks. <strong>While there, be sure to see: </strong>The waterfall with black eagles nesting on the cliffs beside it. <strong>Website:</strong> <a href="" target="_hplink">Walter Sisulu National Botanical Garden</a>

  • Singapore Botanic Gardens, Singapore

    <strong>Worth a visit because:</strong> The plant collection features the National Orchid Garden. <strong>Description: </strong>The National Orchid Garden is located on several acres on a hillside and contains more than 1,000 orchid species and 2,000 hybrids. There are several attractions that compose the collection. They include an orchidarium where orchids found in nature are displayed in a tropical setting, a mist house that includes fragrant orchids, and a cool house that features orchids from tropical highlands and simulates the conditions of cool highland forests. Other gardens include a tract of primary tropical rain forest that is older than the gardens, a ginger garden, a botany center and a children's garden. The Singapore Botanic Gardens is the only botanic garden in the world that is open from 5 a.m. to midnight every day of the year. <strong>Best time to visit: </strong>The garden is a year-round treasure trove of plants and blooms. <strong>While there, be sure to see: </strong>The tropical palm collection, which contains more than 115 genera and 220 species. <strong>While there, take time to see: </strong>Gardens by the Bay, a new horticultural and leisure attraction. It is one of the significant projects which represent Singapore's transformation from a "Garden City" to a 21st-century "City in a Garden," where greenery and flora are appreciated as a part of everyday urban life. The project features three waterfront gardens and is opening in stages. Bay South Garden, the largest, opened in June 2012. If you go, be sure to see the two massive, domed climatrons -- one for intermediate plants, the other for those that grow in a cloud forest. <strong>Websites:</strong> -- <a href="" target="_hplink">Singapore Botanic Gardens</a> -- <a href="" target="_hplink">Gardens by the Bay</a>

  • Butchart Gardens Victoria, British Columbia, Canada

    <strong>Worth a visit because:</strong> It is an internationally acclaimed floral show garden with a "Wow!" factor. <strong>Description: </strong>The gardens got their start 108 years ago when Jennie Butchart decided to turn an abandoned limestone quarry that her husband, Robert, had mined for his cement business into a Sunken Garden. Little by little, other gardens blossomed and were designed to reflect the Bucharts' travels. These gardens now include the Japanese Garden, the Italian Garden and the Mediterranean Garden. With the area's temperate climate, plants are in flower for much of the year. The gracious and elegant traditional setting of the displays adds to the charm of the gardens and the visitor experience. Summer brings fireworks shows, entertainment and night lighting. The gardens are also recognized for their Magic of <a href="" target="_hplink">Christmas</a> displays. <strong>Best time to visit:</strong> July-August. <strong>While there, take a side trip to: </strong>VanDusen Botanical Garden. The mild Vancouver climate is conducive to an outstanding plant collection that includes 255,000 plants representing 7,300 plant families. The plants are grouped in garden areas to illustrate botanical relationships such as the Rhododendron Walk, or geographical origins, as in the Sino Himalayan Garden. <strong>Websites:</strong> -- <a href="" target="_hplink">Butchart Gardens</a> -- <a href="" target="_hplink">VanDusen Botanical Garden</a>

  • Arboretum Wespelaar, Belgium

    <strong>Worth a visit because:</strong> Of the incredible collection of well-documented woody plants from all over the world displayed in a beautifully maintained English park style setting. <strong>Description:</strong> The Arboretum Wespelaar is known for its specialized collection of about 2,000 different species and cultivated varieties of trees and shrubs from known wild origin. The collection is extremely varied and includes woody species, giants and prostrate dwarfs, those that are common and others that are rare, some that are beautiful and some that are less glorious. Perhaps, most importantly, many that are threatened in the wild and can live in the temperate Belgian climate have found a home at the arboretum. <em>Acer, Magnolia, Rhododendron</em> and <em>Stewartia</em> are particularly well represented. Other genera in the arboretum include Betula, Carpinus, Euonymus, Ilex, Tilia, Quercus, Styrax and Viburnum. <strong>Best time to visit:</strong> The gardens are of visual and botanic interest in all seasons. <strong>Website: </strong><a href="" target="_hplink">Arboretum Wespelaar</a>

  • Royal Botanic Gardens, Kew, London, United Kingdom

    <strong>Worth a visit because: </strong>The gardens contain the world's largest collection of living plants. <strong>Description:</strong> Founded in 1759, and declared a UNESCO World Heritage Site in 2003, Kew Gardens in London and its country estate, Wakehurst Place, hold more than 1 in 8 of every known plant species. There are more than 30,000 plants in the living collections and the herbarium is one of the largest in the world. Plant collections include carnivorous plants, cacti, arboreta, British natives, ferns, palms, grasses and economic plants. <strong>Best time to visit: </strong>Kew is a great place to visit at any time of year because the changing displays offer horticultural highlights during every season. <strong>While there be sure to see:</strong> The huge palm house, which dates to 1844 and is considered the most important surviving Victorian iron and glass structure in the world. The Victorian glass Temperate House, which opened in 1863, is even larger than the Palm House. It features a huge collection of semi-hardy and temperate plants. <strong>While there, take a side trip to Scotland to see: </strong>The Royal Botanic Garden in Edinburgh (RBGE) and the Glasgow Botanic Gardens in Glasgow. RBGE is the second oldest botanic garden in Britain after Oxford. It was founded in 1670 as physic garden to explore the relationship between plants and medicine. It boasts the world's largest living collection of Chinese plants (such as rhododendrons) outside of China and also features a world-famous rock garden. The Victorian Palm House -- the tallest of its kind in Britain -- is the entrance to a glasshouse range taking visitors through 10 climatic zones. In Glasgow, be sure to see the Kibble Palace, a huge Victorian glasshouse. These glasshouses and the ones above at Kew are among the few left in Britain from the Victorian era of plant exploration. <strong>Websites:</strong> -- <a href="" target="_hplink">Royal Botanic Gardens, Kew</a> -- <a href="" target="_hplink">RBGE</a> -- <a href="" target="_hplink">Glasgow Botanic Gardens</a>

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