Angel trumpet (Brugmansia) is hardy in U.S. Department of Agriculture plant hardiness zones 8 through 12, although it dies to the ground during winter in USDA zones 8 and 9. It may grow as a shrub or a tree, reaching heights of 5 to 12 feet depending on the cultivar. The plant is native to South America and blooms with drooping, trumpet-shaped flowers from summer through autumn. Before planting angel’s trumpet plants, consider placement because it is a poisonous plant. Other considerations include sun exposure and soil pH.
Finding a Planting Site
Before determining what to add to the soil, select a planting site with full sun exposure and well-draining soil because angel trumpet plants will not tolerate wet feet. Clear the area of any weeds and debris, till it to depths of 12 to 15 inches to loosen compacted soil and conduct a soil pH test. Testing kits are widely available at garden centers and allow gardeners to determine the soil's pH, a scale that ranges from 0 to 14. A pH of 7 indicates that the soil is neutral. Readings of 6.9 or lower indicate acidic soil, while readings of 7.1 or higher indicate alkaline soil. The measurement of soil pH is important because it affects plants' abilities to absorb nutrients.
In general, gardeners should not need to add lime to the soil as part of their site preparation. According to the International Brugmansia and Datura Society, angel trumpet plants prefer growing in slightly acidic soil with an ideal pH of 6.0. The plants will tolerate soil with a pH between 5.5 and 7.0. Since lime increases soil pH and makes it less acidic, it should only be used in acidic soil with a pH below 5.5. According to Clemson Cooperative Extension, ground agricultural limestone is the type of lime most frequently used to increase soil pH. Other types of lime include pulverized, pelletized, granular and hydrated lime.
How to Lower pH
While lime should be used to raise the pH of very acidic soil, gardeners with very alkaline soil may need to decrease the soil's pH. Some of the most common materials used for acidifying the soil include sulfur and aluminum sulfate. Aluminum sulfate works quickly to lower the pH, while sulfur can take several months. The amount of the product needed depends on the current pH of the soil and the product being used.
Fertilizing and Watering Plants
Brugmansia Growers International recommend fertilizing angel trumpet plants with a water-soluble fertilizer twice weekly. Slow-release fertilizing formulas are not recommended because they don't release enough nutrients at a fast enough rate to really benefit these relatively heavy feeders. A solution of 1 tablespoon of Epsom salts dissolved in 1 gallon of water can be applied once a month to give the plants a boost of magnesium sulfate. Fertilize the plants only during the growing season. These plants also need frequent watering to thrive, with at least 1 inch of water weekly. Although the plant can withstand droughts, gardeners might need to water angel trumpet daily during hot, dry weather to prevent wilting.
- The New Sunset Western Garden Book; Kathleen Norris Brenzel
- Floridata: Brugmansia suaveolens
- Clemson Cooperative Extension: Changing the pH of Your Soil
- International Brugmansia and Datura Society: Brugmansia Terms and Definitions
- Brugmansia Growers International: Tips for Growing Healthy Brugs