7 Botanic Gardens for (Almost) Any Growing Zone

Roadside attractions. Jam band festivals. Comic book conventions. National Parks. Everyone has their dream road trips and nerdfest bucket lists. If you're an insanely-obsessed gardener, start making plans to pack up the grocery-getter Griswold-style and hit the road (or book a flight or two) because we've got your next vacation mapped out for you.

We've picked the best botanical gardens for each USDA Hardiness Zone, and we promise there's enough for your non-gardening family members to do so they won't hate you (much) come Labor Day!

Desert Botanical Garden: Phoenix, Arizona

Phoenix and the rest of the American Southwest may share overlapping growing zones with Florida and Hawaii, but the official zone map doesn't account for moisture. Obviously, there's a massive difference between climate so if you're looking for species that appreciate a little "dry heat," the Desert Botanical Garden in Phoenix is one of the best places for inspiration.

Short "loop" trails feature different biomes within the Sonoran Desert ecology. The most extended loops are about a third of a mile long, but you'll want to take your time checking out the more than 4,400 species — including 400 endangered plants, a ton of rare cacti, and all your favorite Southwestern desert wildflowers.

• Size: 144 acres, with 50 acres under cultivation
• Species: 4,400 including 400 endangered species and more than 15,000 individual cacti plants
• Notable Feature: The Desert Botanical Garden Schilling Library houses nearly 10,000 books and documents relating to local native species, and you can arrange an appointment to view its impressive collection of rare botany books and prints.
• USDA Hardiness Zone: 13

Denver Botanic Gardens: Denver, Colorado

If you're visiting the Mile-High City, weed isn't the only horticulture drawing in tourists. The 24-acre York Street park is the clown-car of botanical gardens, hosting nearly 50 themed exhibits. Denver Botanic Gardens has everything you'd expect from a world-class exhibit garden with a focus on Western natives, prairie plants, and arid steppe species from North and South America, Eurasia, and South Africa.

The Mordecai Children's Garden is three acres of interactive play and learning for kids aged one to eight. Built as part of the park's recent $75 million overhaul, it combines natural-material play structures with native plants and soils. No Technicolor swing sets or jungle-gyms here, folks.

• Size: 24 acres 
• Species: Too many to list! Learn more about each exhibit garden here. 
• USDA Hardiness Zones: 5a-5b
• Notable Features: The Science Pyramid is worth visiting for its architecture alone, but its engaging and interactive exhibits allow visitors to learn more about ongoing botanical studies around the world.

Arctic-Alpine Botanic Garden: Tromsø, Norway

We were hoping this spot would represent the coldest equivalent to the USDA Hardiness Zones, but the Gulf Stream keeps the weather at the world's northernmost botanical garden relatively mild and stable during the winter—even though it's less than two degrees south of Barrow, Alaska. Still, the short growing season, though beefed up with about five weeks of continuous sunlight, gives Norwegian gardeners a run for their money.

In spite of maintaining average annual temperatures between 21°F to 59°F, the Garden showcases plants from other cold-weather or polar regions, including southern Chile, the Himalayas, the Rocky Mountains, and the Arctic Tundra. The sun-warmed boulder-strewn exhibit keeps the Mediterranean, South African, Lebanese, and Turkish natives happy. The Garden's website notes that arctic-loving plants grow just feet away on the north side of their rocky ridge exhibit, a testament to how heat stored in thermal mass and solar exposure creates drastically varied microclimates.

• Size: 3.8 acres
• Species: Hundreds to thousands, within 25 collections organized by geographic origin and type
• USDA Hardiness Zone: 9
• Notable Features: Traditional Norwegian garden with heirloom varieties cultivated since Vikings were crushing Europe. 

National Tropical Botanical Garden, Kauai & Maui, Hawaii & Coconut Grove, Florida

With five gardens on Maui, the north and south shores of Kauai, and in Florida, the National Tropical Botanical Garden really should have an "s" at the end. Horticulture students and botany enthusiasts from around the world come to study equatorial and subtropical plants, including those threatened by extinction. The NTBG makes a big deal of the high-yield, nutritious breadfruit plant with the purpose of optimizing genetics for food security and reforestation.

• Size: Just shy of 2000 acres over five locations
• Species: "Thousands," including the most diverse collection of breadfruit species, and the largest number of native Hawaiian flora. 
• Known For: The Breadfruit Institute
• USDA Growing Zones: 10-12b

Butchart Gardens: Brentwood Bay, British Columbia

What do you do with a played-out limestone quarry? If you're Jennie Butchart, you build one of the world's most spectacular gardens. Mrs. Butchart, who owned the property with her husband, began creating gardens in 1906 and in 1939 she handed everything over to their grandson Ian Ross. It's safe to say he took the ball and went long.

Butchart Gardens is a must-see if you're visiting South Vancouver Island. The area mimics a cool, coastal Mediterranean climate, with a few extra hours of sunlight during the summer months. They showcase Mediterranean species and maintain a gorgeous Japanese garden, but Butchart is almost as famous for its roses as it is for the sunken garden landscaped in the original quarry itself.

If you get a bit of rain on your trip, you can duck into any one of 26 greenhouses. Visitors are encouraged to chat up the fifty gardeners, especially if they want help identifying a species not included in their illustrated guide.

In spite of all the themes, Butchart Gardens has a very English aesthetic, reflected in its restaurants, shops, and greenhouse. You can even have tea or reserve (in advance) a picnic basket for that romantic English period film experience.

• Size: 55 acres
• Species: Thousands! There are 900 different bedding species alone, plus hundreds of thousands of individual spring bulbs. 
• USDA Hardiness Zone: 8b to 9a
• Notable Features: The sunken garden that started it all, as well as moorings for visitors arriving by boat or seaplane.

Missouri Botanical Garden: St. Louis, Missouri

We quote these guys all the time, and not just because their climate is somewhat smack-dab in the middle of our continent's hardiness range. Missouri Botanical Garden is a massive resource for international amateur, professional, and academic horticulturists, and the grounds themselves offer all sorts of interactive educational displays for all ages.

We'll let their website wow you with descriptions of their endless outdoor and indoor exhibits — including a 14-acre Japanese garden — but what we find particularly interesting is their weather-mapping and monitoring project. The Remote Automated Weather Station (RAWS) crunches data collected from sensors around their residential test garden facility. These sensors measure minute changes in temperature, solar radiation, barometric pressure, and moisture in the air and soil in real-time. Why is this such a big deal? It helps gardeners design according to their properties' microclimates, shedding more light on growing conditions than the relatively broad and continuously shifting USDA Hardiness Map.

Speaking of microclimates, we saved the best for last: The Climatron is the first Buckminster Fuller-inspired geodesic conservatory. Encompassing 24,000 square feet, the glass and translucent aluminum dome houses humidity-loving jungle plants, water features and cascades, and 1,400 tropical species.

• Size: 79 acres, with larger study and conservation areas outside St. Louis
• Species: We didn't get a return call with the total species, which is funny because the Missouri Botanical Garden has one of the most detailed plant identification and data collection systems in the world. Really, though, it's our fault — we were too busy weeding to follow up. 
• USDA Hardiness Zones: 7a-7b
• Notable Features: The Garden's collection of rare and endangered orchids is the largest in the world, and most of them are housed in the Climatron. Residential landscapers will get plenty of inspiration at the off-site William T. Kemper Center for Home Gardening, "the nation's most comprehensive resource center for gardening information," which displays nearly two-dozen residential-scale demonstration gardens. In other words, it's the IKEA showroom equivalent for gardening geeks. 

Georgeson Botanical Garden: Fairbanks, Alaska

You won't find many details on its website, but if you look at online reviews of Georgeson Botanical Garden, you'll see raves such as "Great cabbages!" and "A messy, interesting place." But don't let that dissuade you from stopping by for an hour or two if you happen to be in Fairbanks. It's run by volunteers from the Georgeson Botanical Garden Society and students at the University of Alaska who have to cram a lot of stuff into their short summers. Word is, the garden's being fixed up as we write this.

The park is named for Charles Christian Georgeson who, under the USDA, established Alaska's system of agricultural experiment stations around the turn of the 20th Century. The Garden was still under operation as a federal wildflower study site until 1991.

Alaska's interior gets the brunt of Northern weather. Fairbanks' winter lows average about -17°F with at least a week of "time to book a trip to the Bahamas" -40°F nights. It's the perfect experimental and teaching garden for those who want to grow food, herbs, and ornamentals in the most challenging of environments, and their workshops are a draw for local homesteaders and other self-reliant types. Plus, it's a popular spot for picnics and weddings.

• Size: Five acres
• Species: A lot of cabbages, apparently, but no official count. The only place you'll find peonies growing in July.  
• USDA Hardiness Zone: 2a
• Notable Features: Alaska's largest hedge maze! A relaxing and quiet picnic spot. Watch out for bears and moose.

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