cestrum
( SESS - trum )
At-A-Glance Information
This group of evergreen shrubs, commonly called Hammer Bush or Jessamine, have bright flowers and grow quickly in sheltered areas of the garden. They need partial shade and regular water for best performance. Hummingbirds and butterflies will frequent this bush and its showy, fragrant blooms. These shrubs have an arching habit that does well with frequent pinching and pruning after the flowering season has ended. They can be damaged by frost, but recover quickly and will bloom in the same season. Fruit follows flowers. Take care when planting these in your garden, as they are poisonous to humans if ingested in large amounts.
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Cestrum Species and Varietals
The genus Cestrum includes between 150 and 250 species, and is a member of the family Solanaceae. The best growing zones for Cestrum vary depending on the species grown. For more information, see the descriptions below. To find your zone, click here: Zone Map.
Cestrum aurantiacum (Orange Cestrum) Grows best in zones 16, 17, 21-24, H1 and H2. Native to Guatemala, this shrub grows to 8 feet tall and wide. Orange flowers appear in late spring and summer, followed by white berries. Leaves are green, and this species can be used as an espalier. Can spread by suckers, and will lose its leaves in cold temperatures. |
Cestrum elegans (Red Cestrum) Grows best in zones 13, 17, 19-24, H1 and H2. This is a vining shrub that is native to Mexico, and grows to be 10 feet or more in height and width. Leaves are deep green and flowers are purplish-red. Red berries appear after the blooming period. Variety 'Smithii' has pink flowers. |
Caring for and pruning cestrum shrubs
These plants are not frost-hardy; they will die to the ground in frost conditions but regrow, though in many areas are grown as annual shrubs. Plant in springtime, after the last danger of frost has passed. They prefer fertile soil that has a pH between 6 and 8 and is well-draining (loamy or sandy soils are great) and to be grown in full sun to partial shade. Keep the soil moist, but not wet, never allowing it to dry out completely. Fertilize once or twice a month in the growing season with a half-diluted, balanced fertilizer. Cestrum can be grown in pots, either outdoors, indoors or in a greenhouse. Those grown in these conditions will need to be repotted every two to three years. Because Cestrum shrubs are fast-growing, they can really be pruned any time of the year to control shape and size, though the best time is in spring before new growth starts to emerge.
Propagation
Cestrum can be propagated either by using cuttings or from seed. To ensure that your propagated plant will have the exact same qualities and characteristics as the parent plant, use the cutting method. If you would like to experiment and see what plant you can grow from seed, just keep in mind that it will not necessarily be the same as the parent plant. To propagate your Cestrum shrub, follow the instructions below:
Propagating Cestrum by Cutting
Propagating Cestrum by Seed
Propagating Cestrum by Cutting
- Gather your materials. You'll need a clean, sanitized, sharp pair of garden shears, rooting hormone, a pencil, and a 3-inch pot filled with well-draining compost or other organic material. If you don't have any potting medium on hand, you can make some. Just mix together equal parts (by volume) moss peat and horticultural-grade sand or grit sand.
- In spring, choose the plant that you'd like to propagate. Ensure that this plant has had a good watering the night before, as this will improve the chances your cutting will take root. Cut one or more 3-4 inch portion(s) of the end of a non-blooming branch and strip the leaves off of the lower half. Make a hole in your planting medium by pushing your pencil into the soil. Dip the end of the stem in rooting hormone, and plant it in your pot. Fill in soil around the cutting to support it, but do not pack it down too much.
- Moisten with water, and ensure that the pot has good drainage. Your pot should be kept in warm (between 70 and 75 degrees Fahrenheit), sunny conditions indoors (but not in direct sunlight). Water whenever your soil is dry under the top layer. After about 1-2 months have passed, your cutting should be rooted. When you notice new growth on your propagated Cestrum, you'll know you have roots.
- Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 70-75 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring, when you can transplant it to its new home. Ensure that the last frost of the year has occurred before doing this, as it can seriously damage your new shrub.
Propagating Cestrum by Seed
- Keep in mind that the plant you get from seed will not necessarily mimic all of the characteristics of its parent. To propagate by seed, you will need gloves, a paper bag, a sealable container, an envelope, a pot or tray filled with well-draining compost or other organic material, a spray bottle and a fork. If you don't have any potting medium on hand, you can make some. Just mix together equal parts (by volume) moss peat and horticultural-grade sand or grit sand. You will also need individual 3-5 inch pots for each seedling that grows (when the time comes).
- Your seed harvesting time will depend on when your specific shrub flowers and goes to fruit (fall is usually a good time for harvesting). The seeds are contained in the fruits, and will be ready to harvest once the fruits have dried up and darkened on the shrub. Once this happens, you can harvest the seeds inside. With gloves on to protect your hands from possible irritation, cut them off of the plant, placing them in a paper bag. Harvest as many as you can, and place the paper bag in a dry, cool, dark area. After a few days, shake the bag to release the seeds from their pods. Once they have been released, take them out of the bag and put them in an envelope inside of a sealable container. Handle carefully to avoid skin irritation. They will stay in this container until the next spring.
- Water your prepared seed tray or pot filled with soil, and ensure that good drainage is occurring. Place your seeds in your prepared pot or seed tray about a quarter inch under the soil surface. Cover them with a light dusting of soil and water with your spray bottle. Place your tray of seeds in a warm area (70-75 degrees Fahrenheit) that receives bright, indirect light. A greenhouse is the most ideal climate, but a planting tray inside a window will do as well. Germination usually takes 7-14 days from sowing. Once you begin to see seedlings sprout and they are able to be handled (they should be about 6 inches tall), transplant them to their own individual pots, filled with the same potting medium as described in Step 1. Loosen the seedlings from the potting medium by digging down with the tines of your fork about an inch and a half, gently working the seedling up until it is out. Then, replant the seedling in its individual pot.
- Keep the seedling's potting medium moist, but not wet, by spraying the soil with your spray bottle. Keep your new plant in an area with bright light (though not direct sunlight) and at a temperature of about 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring (after the danger of frost has passed), when you can transplant it to its new home.
Problems and Pests
- Scale
- Powdery Mildew
- Fungal Leaf Spot
- Spider Mites
Gallery
Videos
All about Cestrum.
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Growing cestrum in the garden.
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Resources
The New Sunset Western Garden Book: The Ultimate Gardening Guide (2012) - Page 234, Cestrum
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