Park Rules and FAQs

Please help preserve Boyce Thompson Arboretum State Park as a home for plants and wildlife—a living museum where everyone can enjoy and learn about nature.

  • Hours: public hours are from 8 am to 5 pm October through April; Summer hours are 6 am to 3pm during May, June, July, August, and September. The day’s final admissions are an hour before closing time (4 pm during fall/winter/spring, 2 during the summer season). The Arboretum is closed Dec. 25, but open all other holidays.
  • Stay on designated trails at all times.
  • Leashed and well-behaved pets are welcome! Pets must be on a leash no longer that six-feet and under the physical control of the owner. Pet owners are responsible for cleanup. Please do your part to preserve this privilege.
  • Children must be closely supervised by an adult at all times.
  • Smoking is strictly prohibited at the Boyce Thompson Arboretum except in the following Main Parking Lot in front of the Visitor Center.
  • Do not pick flowers, fruits, or and plant parts from any plant.
  • Do not remove anything from the Arboretum grounds including plants, leaves, flowers, fruits, sticks, rocks, feathers or wildlife.
  • Do not damage or harm any plant or animal.

Frequently Asked Questions about the park

1) What is an Arboretum? How do you pronounce it?
An Arboretum is a place that primarily grows trees and other woody plants for display, education, and/or research purposes. Arbor is the Latin word for tree. Boyce Thompson is also a Botanical Garden and we grow a wide range of non-woody plants including cacti and other succulents such as Agaves, Yuccas, and Aloes. Our focus is desert plants from arid lands around the world.

Phonetically, Arboretum is pronounced like this: “ARRRR” (Like a pirate would say) “BORE” (like drilling an ice core sample) “EEE” (just like it sounds) and “TUM” (like the popular stomach medicine). Put them together and you have “Arboretum.” The park's name is often abbreviated to BTA for short.

2) What is the Arboretum’s Mission Statement?
The Mission of Boyce Thompson Arboretum is to instill in people an appreciation of plants through the fostering of educational, recreational, research, and conservation opportunities associated with arid-land plants.

3) What’s here to see and do? 
Visitors can explore more than three miles of paths and trails through 100 acres of natural areas, Gardens and Exhibits including collections from Australia, Africa, Asia, the Mediterranean, the Middle East and North, and South America. Learn about our diverse and interesting collection of plants and why they are important to you, watch for our abundant wildlife, get some healthy exercise while breathing fresh air, and enjoy yourselves in this desert oasis amidst spectacular scenery. See also Park Map.

4) Who was William Boyce Thompson?
“Colonel” Thompson was a self-made millionaire, many times over, who amassed a fortune investing in the stock market and developing copper mines in Arizona just after the turn of the century. Political activity and foreign policy involvement during World War I earned him the honorary title of Colonel in the Red Cross. He founded Boyce Thompson Arboretum to raise awareness of desert plants, Sonoran desert ecology, and the importance of arid lands all across the globe. In 1920, he also founded the Boyce Thompson Institute for Plant Research  which is now at Cornell University in Ithaca, New York. Thompson died in 1930. You can read his life story in the book “The Magnate,” which is available in our gift shop.

5) How old is the Arboretum? How large is it?
Boyce Thompson Arboretum was incorporated in 1926 and opened to the public in 1929. It is the oldest and largest Arboretum in the Southwest and the oldest non-profit corporation in Arizona. The Arboretum is located on 323 acres of deeded property adjacent to Tonto National Forest and a research natural area that extends south to Picketpost Mountain. The developed gardens and exhibits, and the natural areas of Sonoran Desert you will see on a typical walk around the Main Trail encompass about 100 acres.

6) When did the Arboretum become a State Park and how long has it been affiliated with the University of Arizona?
Boyce Thompson Arboretum became part of the University of Arizona in 1965 and is now in the College of Agriculture and Life Sciences. In 1976 it became part of the Arizona State Park system.

7) How many people work here? 
In 2008, the staff totaled 23 people, including full and part-time employees. They all employed by the University of Arizona, except the Park Manager and a part-time store clerk who are employed by Arizona State Parks. Volunteers assist our staff throughout the year and are an invaluable resource helping us maintain and develop the Arboretum.

8) Is it all walking or can we drive through? Are wheelchairs available? Are the trails bike-accessible?
Arboretum trails are for walking, not driving or bicycling. Wheelchairs are allowed, but we do not have “loaner” or rental wheelchairs available. Only half of the Main Trail is accessible by wheelchair. The Demonstration Garden, the Hummingbird-Butterfly Garden, and the Children’s Garden are all wheelchair accessible.

9) How long is the Main Trail? How many miles of trails do you have?
The Main Trail is nearly 1½ long. You can add an additional ½-mile by also walking the nearby High Trail that is on the south side of Queen Creek. It takes most visitors about 90–120 minutes to explore the Main Trail on their first visit. Repeat visitors returning for a quick walk can easily see the whole trail in less than one hour. About half of the Main Trail is accessible by wheelchair and by visitors who use a walker, cane or crutches. Wheelchairs are not allowed on the steep “switchbacks” section of trail above Ayer Lake and just east of the Queen Creek suspension bridge. If you’re looking for additional exercise or want to explore other parts of the Arboretum, another 1½ miles of trail wind through the Sonoran and Chihuahuan Desert Exhibits, the South American and Australian Exhibits and the Demonstration Garden. The Sonoran and South American Desert Exhibits are not wheelchair accessible.

10) Can we bring our dog? What other pets are allowed?
Leashed and well-behaved dogs are welcome. Other pets are welcome as long as they are also leashed and controlled. Please pick up after your pets.

11) Is there a place for a picnic / BBQ? Can we just use the picnic area?
With paid admission or membership, visitors may use the charcoal grilles and tables in our picnic area. No wood fires are allowed.

12) Is food available at BTA? Do you have a café?
Sandwiches, trail mix, candy bars, other light snacks, and drinks are available in the gift shop. We do not have a restaurant on-site, but several good restaurants are just three miles east of the Arboretum in Superior. Ask for the restaurant guide in our gift shop.

13) Can we camp here?
No, there is no camping at this park. You can pitch a tent at the Picketpost Trailhead a ½ mile west of the main gate. Superior RV Park is two miles east of the main gate on highway 60. Camping is also available at the Oak Flats campground in the Tonto National Forest, seven miles due east of the Arboretum on the right hand (south) side of Highway 60.

14) Do you have reciprocal discount agreements with other Arboretums or Botanical Gardens? How about AAA or AARP discounts?
Sorry, no. We typically offer a “two-for-one” admission bargain with the Phoenix editions of The Entertainment Guide, as well as discounts with the Coyote Coupon book that is distributed around Apache Junction. Bring along a copy of our rack card brochure to save $1 on admission for up to four people.

15) What is your annual visitation?
Annual visitation normally varies from 65,000 – 75,000.

16) Membership: what are the levels, how much do they cost, what do they include?
See Membership Information.

17) What should we see if we have limited time?
You only have about thirty minutes or less? You can easily see the Hummingbird-Butterfly Garden and the Demonstration Garden. These are two of our prettiest collections, and they’re also the two easiest to reach with a short walk. The Hummingbird-Butterfly Garden is a one-minute walk downhill from the Visitor Center, and the Demonstration Garden is just across the Picnic Parking Lot.

Got an hour? You can easily walk up to Ayer Lake and explore the Cactus Garden along the way. Time permitting, enjoy your walk back through the Chihuahuan Desert Exhibit. Alternatively, in one hour you can walk to the Herb Garden through the Eucalyptus Forest and, if in good shape, return via the High Trail beginning on the other side of the suspension bridge and ending in the Picnic Grounds. For those who are in really good shape and don’t stop to read the interpretive signs or take photos you can easily walk the entire Main Trail, seeing many of the Arboretum’s main sights, and be back at the Visitor Center in less than an hour.

18) Do you have a checklist or a trail guide?
Our gift shop clerks can provide separate (and free) checklists for birds, butterflies, dragonflies, lizards and “plants of the bible”. We also have a Main Trail guidebook available for $1 (English, Spanish, German, French and Japanese) with information corresponding to numbered signs along the trail, so you can learn much more about plants, animals and natural history on your walk. You can also purchase a $1 trail guide (English, Spanish) for our Curandero Trail that describes medicinal and other uses of Sonoran Desert plants. “Loaner” binoculars are also available.

19) Do you have anything for kids to do?
Our new Children’s Garden opened in 2008 and offers kids a chance to explore a variety of displays including four gardens designed to stimulate the senses of sight, smell, hearing, and touch (texture). There is also a human sun dial, a maze and a treasure hunt to explore and enjoy. When you arrive at the admission booth or window at the gift shop, inquire about the Arizona State Parks Junior Ranger kit. Our staff will provide a free activity writing project kit that kids can use to learn about nature while exploring our gardens. Kids who complete the form earn a Junior Ranger badge! Our most popular guided tour for children is the summertime “Learn Your Lizards” guided walk. This tour is offered on the second Saturday each month and included with daily admission.

20) Do you sell plants? Do you ship plants that you sell? Can we take these plants on our plane or across state lines?
We sell a large variety of plants including succulents such as cacti, agaves, aloes and haworthias along with trees, shrubs, herbs and flowers in many different sizes. Plants are sold year-round at our visitor center, but a larger selection is available during the seasonal plant sale fundraisers in October and March. We do not ship plants, but will pack up to one-gallon size potted plants and cactus dish gardens – and also provide necessary USDA documentation so your plant(s) can be carried onto a plane and taken anywhere within the continental United States.

21) How many different types plants (taxa) are there at the Arboretum?
There are approximately 3,100 different taxa (types of plants) of accessioned perennial plants in the Arboretum’s collections, not including the hundreds of native perennial and annual plants that can be seen throughout the grounds. These taxa are largely represented by the following 10 plant families: Cactaceae (Cactus Family) – 567 taxa; Leguminosae (Pea or Bean Family) – 299 taxa ; Iridaceae (Iris Family) – 179 taxa; Liliaceae (Lily Family – includes Aloes) – 176 taxa; Myrtaceae (Eucalyptus Family) – 161 taxa; Agavaceae (Agave or Century Plant Family) –157 taxa; Compositae (Sunflower Family) – 131 taxa; Labiateae (Mint Family) – 104 taxa; Rosaceae (Rose Family) – 86 taxa; and Palmae (Palm Family) – 47 taxa.

22) What is the total number of plants in the Arboretum’s collections?
There are over 14,000 individual plants in the Arboretum’s collections growing out on the grounds. We maintain records on all of these plants and map them whenever possible. The majority of these are in the Cactus Family (2,688) followed by the Legume or Pea Family (1,905); the Agave or Century Plant Family (1,286); the Eucalyptus Family (792); the Lily Family (602); the Sunflower Family (536); the Mint Family (338); the Iris Family (211); the Palm Family (183) and the Rose Family (181).

23) What’s the biggest tree at the Arboretum?
“Mr. Big” is a massive red gum eucalyptus (Eucalyptus camaldulensis) in our Australian collection. It is easy to find after you cross the white bridge over Silver King Wash adjacent to the Drover’s Wool Shed. Just turn right on the Main Trail and walk a short distance. This venerable tree was planted in 1926 and reaches over 140 feet skyward. It is on the registry of big trees as the largest individual of this species in the United States.

24) When do the cacti flower? When do saguaros bloom?
Our native Hedgehog cacti have beautiful pink to purple flowers and normally bloom from early March into April, peaking mid-March to early April. Opuntia species such as the native yellow-flowered Englemann’s prickly pear and the orange/red flowered Staghorn cholla bloom in March/April. The Saguaro (our state flower!) begins flowering in May and June. The Arboretum also has many exotic cacti from Mexico and Central and South America that can flower throughout the year except during the colder months of November - January.

25) Do any cactus flowers stay open for more than a day?
Yes. Many species of Prickly pear (Opuntia), Cholla (Cylindropuntia), Hedgehogs (Echinocereus), Barrel Cactus (Ferocactus) and Pincushion Cactus (Mammillaria) have blossoms that last more than one day. These are also our most common cacti.

26) What is a Jumping Cholla? Do you have Leaping Lizards? 
“Jumping” Cholla are a common type of cactus with an erroneous nickname. Joints don’t really fly off these plants, but they can break off easily. Their barbed spines dig in, readily attaching to clothing, skin, and shoes – and careless pets that accidentally brush past one of these Cholla plants. Leaping Lizards? Well, lizards will jump... Our most commonly seen ones include the Tree, Side-blotched, Greater Earless and Desert Spiny Lizard -- but there’s not a species here at BTA known as a “Leaping Lizard.”

27) What desert plants are edible?
Many are edible, and some quite tasty, nutritious and even medicinally useful, but you need to be sure you know the identity of the plant before using it in any way. Young prickly pear pads can be de-spined, diced and scrambled with eggs or pickled. The plants magenta-red fruit is used in jams, punches, etc. The tender shoots of tumbleweed (an invasive, non-native plant) are a delicacy, jojoba seeds have a pleasant, nutty flavor, and white yucca flowers are edible (though mildly bitter). Mesquite pods are flavorful, mildly sweet and nutritous. They are, along with the tasty, orange fruit of the desert hackberry, enjoyed by man and animals alike. Want to learn more? Attend our monthly “Edible/Medicinal Desert Plants” guided walking tours on the fourth Sunday of each month. During the winter and spring months, there is also a tour on the second Saturday of the month. You can read lots more about edible plants on our website!

28) What is a century plant and why is it called that?
“Century plant” is a common, but inaccurate, nickname for the approximately one-hundred and thirty different species of Agaves native to the Southwest and Mexico. Our local Agave is the Golden-flowered Agave (Agave chrysantha). As a group or species, they are all commonly known as “Century plants” because of their supposed longevity. The truth is they don’t even live close to 100 years before sending up a huge flower stalk. Their average lifespan is only 6-30 years, depending on the species. Once Agaves flower they die – with a few exceptions. They reproduce themselves either by seeds from the often candelabra shaped flower cluster, by “pups” or “offsets” (known as “hijos” in Spanish) that sprout from the root system of the mother plant or, in a few species, by producing miniature plants on the flower stalks called bulbils. The pups and the bulbils are genetically identical clones of the mother plant.

29) Can I drink the water from a barrel cactus?
Yes, but don’t do it! Barrel cacti do contain fluid in the pulpy flesh beneath their forbidding armor of spines, but it contains toxic alkaloids, unfit for drinking. Moral of the story? Always carry water when you’re hiking in the desert! Hiking guides will tell you to pack along at least one gallon per person if you’re walking out in the desert where water is unavailable. For a walk here at the Arboretum we recommend a typical 32-ounce bottle, and you can re-fill at water fountains in the Desert Legume Garden, Herb Garden, and Picnic Grounds.

30) Is there poison ivy at the Arboretum? 
No, not here, but you will encounter poison ivy if you hike higher elevation mountain canyons in Arizona.

31) What wild animals will we see at the Arboretum? Are there any snakes? What kind of snakes? 
The most commonly seen mammals are the fat, gray rock squirrels, the speedy little cliff chipmunks with striped faces and the cotton-tail rabbits. Less frequently seen critters include the gray fox, bobcat, javelina, coyote, white-tailed deer, raccoon, skunk, coatimundi (related to raccoons, about the same size, but with long tails and pointy snouts), and an occasional mountain lion. We also have an abundance of birds, lizards, and butterflies.

There are several snakes that live at the Arboretum. The non-venomous bull snakes, racers, and whipsnakes are the most common and active, thus the most frequently seen, followed by the venomous western diamondback rattlesnakes. Don’t touch, bother or try to move any of these snakes. They all live here in the Gardens and are beneficial for rodent control. Let our staff know if you cross paths with a rattler which seemed particularly ornery: those we’ll relocate, when necessary, to quiet locations out of harm’s way and far from the Main Trail.

32) Are tarantulas poisonous?
No, and neither are rattlesnakes or scorpions. They are all venomous, not poisonous. This may seem like splitting hairs but poisons are ingested (eaten) while venoms are injected. Tarantulas are very docile and seldom bite. If you should threaten them sufficiently their bite feels much like a bee sting. Tarantulas, scorpions, and rattlesnakes are maligned and misunderstood creatures: the hype about these venomous critters of the Sonoran Desert does not match the truth. They know that humans and their pets are a threat — not food items or prey. These shy creatures prefer to avoid an encounter and flee. A hissing, rattling rattlesnake is more likely feeling defensive than aggressive; don’t handle these creatures if you see them on the trails. Don’t panic either — take a few steps back, then take a minute to observe at a safe distance, take a photo or two, and allow the creature to cross the trail and return to a hiding place.

33) What birds are at BTA now?
The colorful Northern Cardinals are year-round residents and most often found near the Herb Garden, Picnic area and along Queen Creek. Other birds which can be seen and heard all year include the Canyon Wren (listen for them inside the Visitor Center and in nearly all of our Garden collections), Black-throated 
Sparrow, Curve-billed Thrasher, Verdin, Northern Mockingbird, Black Phoebe, Cooper's Hawk, Broad-billed Hummingbird, Abert's Towhee, Song Sparrow and Great-tailed Grackle.

Want to read an updated checklist report which includes seasonal migrants or exciting transients that recently stopped in to rest and refuel in the gardens? Visit our website bird sightings page or call the recorded message phone at (520) 689-2811 and press "8" for the most recent checklist report.

34) What other birds look like a Cardinal? 
During the summer months we have migrants which include the Summer Tanager and the Vermilion Flycatcher. Both birds are red, like a cardinal, but with different body shapes. Take a look at the Sibley or Kaufmann field guides to birds in our bookstore.

35) Do Turkey Vultures mate and lay eggs while they are here at BTA?
No. The turkey vultures roosting here from about March through September are an immature and non-breeding population according to authorities from the Arizona Game and Fish Department. It’s likely that some vultures may nest in the cliffs of Picketpost Mountain which overlooks the Arboretum, but we do not have evidence of them nesting.

36) How hot (or cold) does it get at the Arboretum? How much rain do you have?
See Weather.

37) When does Queen Creek flow?
It flows seasonally usually for at least a month or two in the winter during January and February, then again with the summer rains during July and August, but not for very long. Queen Creek actually flows all year long, even during the dry months it still flows underground when the visible creek bed is bone dry.

38) Where does Ayer Lake get its water?
From Queen Creek. There’s a shallow well located in the canyon just east of the suspension bridge that spans Queen Creek and leads to the High Trail. Water from the well is piped up and over the cliffs, then flows downhill through a drainage to the lake, entering at the east end. If you’re walking near the Picket Post Mansion, listen and look for the artificial “waterfall” splashing down from the cliffs above when the lake is being refilled! We have another well along Queen Creek at the west end of the Arboretum near the Highway 60 Queen Creek bridge. Ayer Lake is the source of irrigation water for our collection plants.

39) Are there any fish in Ayer Lake?
Yes. The Desert Pupfish and the Gila Top Minnow live in Ayer Lake. They are both endangered fish and are used by Game & Fish to stock other bodies of water where the fish have died off.

40) What is Picketpost House? Is this mansion part of BTA? 
The impressive mansion perched atop the volcanic magma cliffs just east of the Arboretum was the winter home of our founder, Colonel Thompson, back when the Arboretum was created in the 1920s. The mansion was sold and remained in private hands for decades, but was re-acquired by Arizona State Parks in 2008. Arizona State Parks will cooperatively manage the “castle on the hill,” which may re-open for occasional tours in 2009.

41) Was there really an elevator from the Picket Post house down to the canyon floor? 
No. Despite an interpretive sign in the wooden shade ramada at the east end of the Arboretum, which erroneously tells visitors there used to be an elevator descending to the canyon floor! That’s inaccurate. There was, however, an elevator in Boyce Thompson’s “bedroom house” (it burned down in the 1950s) that took him to the roof top where he could view the Arboretum and the rest of his holdings.

42) Can you climb Picketpost Mountain … are there trails there from the Arboretum?
Yes, you can hike Picketpost Mountain, but you need to leave the Arboretum and drive a half-mile west to access the trailhead which is about a quarter of a mile southeast of Highway 60. Picketpost Mountain is a great climb — but challenging if you don’t hike much, and the trail can be difficult to find. It ascends the west face of Picketpost and takes about 2-3 hours, gaining 2,000 feet in elevation. Views from the peak are stunning and on a clear day you’ll see the Catalina Range near Tucson, the Pinal Mountains looking east, and the Superstitions and Weaver’s Needle looking west. You will have a bird’s eye view of the Arboretum, Queen Creek, and Arnett Canyon. Make sure to find the famous mailbox at the southwest side of the top and leave your comments in the visitors’ ledger! The Picketpost trail is just off the Arizona Trail.

43) Is Globe called the Cobre Valley because it has cobras?
“Cobre” is Spanish for copper, not for a species of snake. “Cobre Valle” = “Copper Valley.”

44) What is the best time of year to visit BTA? When can we see the most flowering plants?
Right now is the best time. You can enjoy the beautiful scenery, the abundant wildlife, and there is always something blooming even in the summer as well as the coldest months from late November-through-January when you will find flowers blooming in the Demonstration Garden, the Hummingbird-Butterfly Garden (until the first hard frost) and the Children’s Garden. Spring flowers are at their peak in March and April into early May, and cactus blossoms are prime during April and May though they continue sporadically into mid-Summer when the native fish hook barrels bloom. Call our staff at (520) 689-2723 during daytime business hours to ask about plants flowering during other seasons. The Arboretum is famous in Arizona for its Fall foliage which you’ll see from mid-November through the first week of December. There are always abundant birds around but during the winter months (December, January, February) we have seasonal migrant birds passing through. The hot summer months are the ideal time to see colorful butterflies and dragonflies, and those entertaining lizards, either on your own or with our engaging tour guides. Our “Learn Your Lizards” walks during June, July and August are particularly enthralling for kids. Seriously, drive up this week and visit us as soon as you can. Boyce Thompson Arboretum is a great day-trip all year long.