Brugmansia and Datura

Credit: John Glover

Brugmansia and Datura bring an element of mystery to the everyday garden

“The datura recalls Baudelaire. Its origins are mysterious. In Sanskrit it is synonymous of madness, folly and falsehood. Its tortuous horns appear as if seen through a magnifying glass; its slim corolla bewitch and alarm one… In Moorish gardens [daturas] blend naturally with mosaics and fountains. Their very strong scent is either exquisite or unbearable. According to Indian legend, the datura can make a man lose his head if he inhales it too closely.” I have never forgotten these evocative lines by Robert Joffre, warden of the Garden of Paris and professor of Horticultural Art at the University of Paris. I recall discovering them in a heavy, fragrant book called Gardens and Flowers, their Design and Arrangement. Standing in a bookstore so many years ago, I fell in love, if you will, with Joffre’s expressiveness, the beauty of the book itself and with the magic that plants and gardens create. For me, the sight of one of these magnificent plants in bloom is still a special delight. As Joffre explains, “They are used in many different ways or even planted in boxes. In the latter case, they can be used as an unusual and mobile form of decoration.” “Mobile” is the operative word in British Columbia gardens, because they are only hardy to zone 10 and will not survive B.C. winters out of doors. But first, let’s back up and take a closer look at this group of plants. The common name “datura” refers to annual and shrubby species from the potato family (Solanaceae). Previously, all were in the genus Datura. Now, only the annual species are called Datura, while the shrubby species are called Brugmansia. (Curiously, many potato family members are food crops and many are poisonous. Both Datura and Brugmansia are poisonous. Their sap can also be extremely irritating to the skin and eyes, so wear gloves when handling them.) The plants Joffre describes in his book are the woody Brugmansia, which are also called angel’s trumpets or floripondios (in their native South America). They produce some of the largest flowers known, up to 50 cm (20 in.) long. In the wild, long-billed hummingbirds pollinate the pendulous blooms; in gardens, bees seem happy to oblige. Plants are not generally self-fertile: unless more than one clone is grown, no fruit develop, despite the pollinators’ best efforts. There are five species of Brugmansia and numerous hybrids, but their taxonomy is confusing and sorting out names is a challenge. Generally, types with orange flowers have longer-lasting blossoms than those that are white or pink. Some types are double, resembling the swirling skirts of a flamenco dancer.

Devilish Datura

Will the real Datura please stand up? In fact, it does—in bloom, anyway! While flowers of Brugmansia species are pendent, those of Datura are held erect—welcoming to the night-flying moths that pollinate them. The numerous species of Datura have rounded fruit with spine-like protrusions, which give them one of their common names: thorn apple. All contain deadly poisons called alkaloids. Hundreds of years ago, Europeans used Datura stramonium in magic potions for its anaesthetic, narcotic and hypnotic properties. In large doses, it is hallucinogenic. This well explains a second common name: devil’s trumpet. Similar uses by Inca priests have been documented, and historians even suspect Datura played a role in the oracle at Delphi. In China, too, its dangers were known; there, the plant’s mixture with wine was prohibited by law. These half-hardy annuals are available from most seed suppliers (single- and double-flowered seed strains) and are easy to grow. Plants bloom sooner if started indoors in February or March and set out in the garden once the danger of frost has passed. If the eye-catching (but toxic) fruits are allowed to ripen on the plants, they’ll drop their seeds into the soil and you can count on new seedlings appearing the following spring.

Bewitching Brugmansia

The Brugmansia “trees” that decorate the entrance to the UBC Botanical Garden are among the most impressive I’ve seen. To gather some growing tips, I contacted the garden’s nursery supervisor, Ron Rollo. In a nutshell: “We grow new ones every year.” Ron says that Brugmansia grow so quickly, it is just as easy to start fresh annually. UBC’s routine is as follows. In August, 10 cm (4 in.) long cuttings are taken from the plants at the garden’s entrance. They root easily in 10 cm (4 in.) pots with a peat-perlite medium. A controlled-release fertilizer is added to the mix because Brugmansia, like many potato family members, are heavy feeders. (Ron suggests that home gardeners without greenhouses root cuttings by enclosing the pots in clear plastic to increase humidity.) Ron notes the importance of keeping one central leader to train as a trunk. At UBC, plants are kept in an 18°C (64°F) greenhouse all winter. As plants grow, they are tied to a 1×1 stake, and the branches on the lower 75 cm (30 in.) of trunk are gradually removed. By March trees are 1.8 m (72 in.) tall, set in 22 L (5 gal.) pots, and they have a good crown of lateral branches; they often have flower buds. While Brugmansia are notorious for hosting whitefly, Ron says their nursery is fairly whitefly free. In May, these spectacular exotics take up their posts at the garden entrance. Ron has grown Brugmansia at home as well. By the end of summer, his tree’s roots had filled an oak barrel, which was placed into his garage for winter. Considering the work, the results the following summer were disappointing. Overall, the overwintered plants looked less sumptuous than those started fresh. Once UBC’s Brugmansia are out in the garden, they are heavily fertilized with 20-20-20. Tom Wheeler, the garden supervisor, uses weekly applications at twice the recommended rate to keep these giants green (5 teaspoons per gallon). Tom notes that angel’s trumpets also require full sun and plenty of water. With more than 30 years experience in horticulture in B.C.—in wholesale, retail and at VanDusen Botanical Garden for a decade—Carolyn Jones brings a wealth of knowledge and expertise to GardenWise and www.gardenwiseonline.ca as staff horticulturist.