Cestrum is a genus of plants containing over 200 species, with most varieties producing clusters of trumpet-shaped flowers.
Pronounced [SES-trum], Cestrum plants are native to warm and tropical regions of North and South America, particularly Florida and parts of Texas.
When shopping nurseries for plants within this genus, the young plants may include the common name hammer bush, due to the bushy growth.
Hammer bushes are relatively easy plants to grow, especially in warm regions, but require sunlight and heat to survive the winter.
Cestrum Plant Care
Size and Growth
Most varieties of Cestrum grow fast, producing green leaves and stems of varying lengths.
Cestrums tend to grow about one to three feet per year. The branches of these bushy plants may reach up to 10′ feet when given room to grow.
Orange Cestrum is a popular variety that produces vine-like growth, making it suitable for training on a trellis or growing in a hanging basket.
Red Cestrum elegans produces arching branches and purplish-red berries.
The length of the leaves also varies.
Night jessamine produces leaves measuring four to eight inches while willow-leafed jessamine produces a dense canopy of three to six-inch-long leaves and many branches.
Flowering and Fragrance
The color of the flowers of Centrums may include white, red, orange, or purple, depending on the species.
They tend to bloom in the spring or summer, but flowers may appear at any time of the year.
The trumpet-shaped flowers typically grow in clusters 10 or 12 flowers on the ends of short stems extending from the branches.
Light and Temperature
When grown outdoors, the Cestrum tolerate light shade or full sun. Brighter light helps encourage longer lasting blooms.
If grown behind glass, the plants require bright, indirect sunlight.
Place them in south-facing or west-facing windows for the most exposure to the sun.
Most species of Cestrum are winter hardy in USDA hardiness zones 8 to 11 and can tolerate temperatures down to 50° degrees Fahrenheit during the colder months.
In the summer, Cestrum grows best in temperatures in the upper 70° degrees Fahrenheit.
Watering and Feeding
Never allow the soil to completely dry. Water the Cestrum when the top one or two inches of soil has dried.
When watering, soak Cestrum thoroughly and allow the water to drain around the base.
For healthier growth, feed the plants once or twice per month. Dilute the liquid fertilizer before use.
Soil and Transplanting
Use large tubs, clay pots, or baskets filled with rich soil with good drainage.
In warm regions, the plants can grow in the ground, if they’re not considered invasive in your area.
Potted plants require repotting every two to three years. Repot into larger containers if needed.
Maintenance and Grooming
To encourage bushier growth, trim thin shoots any time of the year.
Cestrum grows about one to three feet per year, depending on the species.
To manage the growth, prune the plants in the spring before growth starts.
How to Propagate Cestrum Bushes
Using branch cuttings provides the easiest method for propagating Cestrums.
Take cuttings from healthy mother plants in the spring.
When taking the cutting, try to collect three to four-inch branches with at least one pair of leaves.
Dip the ends of the cuttings into rooting hormone.
Use pots for the cuttings and fertile soil.
Cover the pots with plastic. Poke holes as needed for ventilation.
Keep the Cestrum indoors or outdoors in temperatures between 70° and 75° degrees Fahrenheit.
After one to two months, the plants should take root.
Remove the plastic and allow the plants to grow for several more months before transplanting to individual containers or pots.
Cestrum Pests or Diseases
Spider mites may pose a threat to your Cestrum.
If the leaves are pale or you notice webbing on the plants, spider mites may have infested the plant.
Spray with an insecticide or miticide.
For severe spider mite infestations, discard the plant before the mites spread to neighboring plants.
Brown patches and sunken leaves indicate scorching from bright sunlight.
Move the plant to a shadier spot or move it further from the window.
Besides pests and diseases, growers may also need to consider whether the species is invasive.
In certain regions, this plant is invasive. Some species are also toxic.
The green Cestrum grows wildly in some regions and contains a high level of toxicity in all parts of the plant, including the branches.
Cestrum laevigatum is a species of hammer bush that contains hallucinogenic properties.
Most species are also considered piscicides, meaning that they are poisonous to fish.
Suggested Cestrum Uses
Hammer bushes prefer bright, indirect sunlight, making them perfect candidates for growth in greenhouses or behind large windows.
Cestrums also grow well outdoors under full sun or light shade.
Depending on the variety, grow them in the garden, from hanging baskets, or on trellises for vines.