Bloom Watch #1 | Tracking the Bloom
June 4, 2025Signs of the Queen
As the dog days of summer settle in over our Sonoran Desert oasis, the queens are beginning to wake.
Every summer, the gardens team at Tohono Chul enjoys the slow-moving spectacle of the Queen of the Night cactus (Peniocereus greggii) budding and flowering. The first hint comes in the form of a few silvery hairs forming on the node (called an areole in cacti), where new branches and flowers emerge from the stick-like limbs of the queens. Within just a few days, the buds begin to look like tar-stained teardrops covered in whiskers. From this point on, the buds will elongate—slowly at first—stalling for weeks until hints of monsoon humidity spur a race to the finish, with buds sometimes growing a centimeter or more in a single day. It all culminates on a hot and muggy night with an unforgettable synchronized fluorescence of milk-white, satellite-dish blossoms, perfuming the night with their heady aroma in hopes of attracting pollinating moths.
But for now, that night is still weeks away.
Caring for the Queens
In the meantime, Tohono Chul gardener Shauna Smith will give the queens a weekly watering to help them through the current period of drought. As the buds grow, she will carefully measure them, tracing their development and helping determine the likely bloom date. We follow this process every year, hoping to learn more about flower development on these enigmatic plants so we can better understand the 182 queens currently growing around Tohono Chul.
A Future Generation
While we care for the plants already in our gardens, Propagation Coordinator Tracey Till and our nursery volunteers monitor hundreds of queens, ranging from three-week-old seedlings to potted specimens grown from seeds collected on the grounds or donated by members. These seedlings represent Tohono Chul’s commitment to ensuring the future of these plants in our landscape and sharing them with the public.
Decades of Data: Cataloging the Queens
Since the first Tohono Chul Bloom Night in 1992, gardeners and volunteers have been tracking growth rates, survival, bud and flower sizes, and bloom dates for the queens. These 32 years of data provide an important baseline for understanding how these plants are responding to climate change and offer insights into how we can care for them into the future.
Tohono Chul’s Living Collections Coordinator, Juliana Ahumada, and her team of volunteers are currently digitizing historic data sets recorded on old note cards and printer paper. The numbers assigned to each plant as part of our living collections mapping are being matched to nicknames bestowed on many queens, like “Big Red,” “Emerald,” and “Ruby.” As this data is entered and organized, we will share our insights with researchers, land managers, and the public to foster a deeper understanding of this unique cactus.
Cultivating the queens and studying their growth is one of the ways Tohono Chul carries out its mission to inspire responsible stewardship through reverence for the natural and cultural ecology of the Sonoran Desert region.
– Written by Jack Dash, Tohono Chul Gardens & Facilities Manager
Stay tuned for more Bloom Watch updates as we await the big night! Click here to subscribe to Bloom Watch e-mails, or look for updates on Instagram or Facebook.
Members Exclusive
Bloom Night is an exclusive members-only event. Your support helps preserve the Desert View Trail and our Peniocereus greggii collection while we work to ensure the proper pollination and delicate nature of these special plants.
Don’t miss out—become a member today and unlock a year of perks and benefits at Tohono Chul, including early access to plant sales, discounts, free daily admission, reciprocal admissions at other public gardens, and much more.
Support Bloom Night’s Future
Each Queen of the Night bloom is a moment of wonder. We’re working to double our collection so more people can experience this magical moment. Your support will help us reach our $5,000 goal to care for seedlings, expand our plantings, and continue our research. Please consider making a gift today!
