Some say datura, others say brugmansia. What is the real name of those beautiful “angel’s trumpets” so often seen in gardens?
Carl Linnaeus himself, the father of taxonomy (the science of the classification of living things), created the genus Datura in 1753, giving it a name derived from dhattūra, the Hindi name of one of the species. He placed the genus in the Solanaceae (potato family). But in 1805, the South African scientist Christiaan Hendrik Persoon transferred one of the species, D. arborea, to a new genus he called Brugmansia, named for the Dutch botanist Sebald Justinus Brugmans.
For 168 years, taxonomists debated the change back and forth, many taxonomists refusing the new name. But in 1973, the taxonomist Tom E. Lockwood published a definitive study on the subject, dividing the genus Datura in two parts: 9 species remained in the genus Datura while 7 species were transferred to the genus Brugmansia.
Telling Them Apart
At first glance, daturas and brugmansias are very similar, because both genera bear large trumpet-shaped flowers and even their big elliptic leaves are very similar. Still, the differences are easy to see.
Brugmansias are large shrubs or small trees with woody stems and their flowers are pendulous. They easily live decades under decent growing conditions. Another difference is that their seed capsules bear no thorns. And they’re slower to mature: seedlings take at least two years before starting to flower.
Daturas are herbaceous (non-woody) plants with upright flowers. Many are large plants (up to 5 ft/1.5 m) with branched stems that can look like a shrub, but they’re short-lived. Most species are annuals, although some can live on for a year or two under ideal conditions. Their seed capsules are generally thorny. Some are weedy plants that can be difficult to control, even in cold climates.
Normally, daturas are treated as annuals, especially in areas with cold winters. Their seeds are harvested in the fall and stored dry in the winter. They are usually sown indoors in February, then transplanted into the garden, in full sun and well-drained soil, in early summer. That way they’ll bloom all summer. Jimsonweed (Datura stramonium) and its hybrids can however been sown directly outdoors in May and will begin to bloom only 8 weeks later.
Usually you buy brugmansias as already rooted plants that you can place outdoors for the summer in full sun and well-drained soil, either in pots or planted in the ground. (For a truly gigantic plant, do consider planting them in the ground!) In the fall, you have to bring them indoors in most climates, otherwise they’ll be killed by frost. You can only leave brugmansias outdoors in areas where frost is unlikely.
Just bring plants already growing in pots directly indoors, but of course you’ll have to dig up any plants you’re growing in the ground and pot them up first. To learn how to bring them back indoors without bringing in insects too, read Bring Your Plants Indoors… Without the Bugs.
Winter Care for Brugmansias
There are two ways to handle brugmansias once you’ve brought the indoors. You can force them into dormancy or keep them growing all winter.
Winter dormancy is not a normal state for brugmansias (it really never happens in the wild), but they adapt quite well to it indoors.
To force a brugmansia into dormancy, cut the branches back a third or more, depending on the space available to you. Place the plant in a dark, cool room (38˚-50˚F/3-10˚C) such as a heated garage or unheated basement. You’ll still need to water them about once a month, although quite lightly. Essentially, you’ll just be making sure the soil doesn’t dry out completely. Any leaves still on the plant when you bring them in will soon drop off. However, pale yellow new shoots will begin to appear in late winter.
In March, move the plant to a well-lit room and start watering it, gradually at first. When green leaves appear, you can also start fertilizing. Acclimate the plant to outdoor conditions when all risk of frost is gone and night temperatures generally remain above 50˚F/10˚C.
Keeping Brugmansias Growing in Winter
To keep your brugmansia growing during the winter, place it in a sunny room as soon as the nights begin to cool off in the fall and keep it well watered and fertilized.
People always want to know at what frequency they should water, as if there were some sort of magic pattern to it, but there isn’t. You have to water deeply, soaking the entire rootball, as soon as the soil is dry to the touch, period. Depending on your growing conditions, that may be once a week, once every 12 days or once every 2 or 3 days. Yes, indoor conditions really do vary that much!
Under good conditions, your brugmansia may continue to bloom for a while indoors, often up to around Christmas, but from then on flowering usually ceases under the influence of short days: your plant is no longer getting enough solar energy to bloom. The plant’s growth too will slow down or stop. Continue watering as needed (when the soil is dry to the touch), but stop fertilizing.
By late March, thanks to lengthening days, your plant will probably start putting on new growth, a sign you need to water more often, again as soon as the soil is dry to the touch. Also, begin fertilizing again. If you have lots of indoor light, your plant may even begin to bloom again indoors, but in many cases, flowering won’t start until it’s outdoors.
As with plants forced into dormancy, it’s time begin acclimating the plant to outdoor conditions when there is no risk of frost and night temperatures generally remain above 50˚F/10˚C.
Finally, note that brugmansias are very hungry plants: you may need to fertilize them weekly to get them to put on a good show of blooms.
All brugmansias and daturas are poisonous. Just don’t eat them.