Calycanthus floridus
If you’re looking for an easy-care shrub for hedging, as a specimen, or to fill out a shady understory, consider Carolina allspice, Calycanthus floridus, also known as eastern sweetshrub.
A deciduous member of the Calycanthaceae family and cousin to the magnolia, this southeastern US native offers glossy green foliage and small, maroon blooms from spring through summer.
We link to vendors to help you find relevant products. If you buy from one of our links, we may earn a commission.
Carolina allspice thrives in USDA Hardiness Zones 4 to 9. In my Zone 7 garden, it tolerates clay soil and shrugs off pests and disease.
Read on to learn how to grow and care for Carolina allspice in your own outdoor space.
Here’s what we’ll discuss:
What You’ll Learn
C. floridus is one of four species in the Calycanthus genus.
Thanks to natural variation, cultivated varieties, and intrageneric hybrids, gardeners can now choose from larger flowers and unique colors beyond the standard maroon.
Carolina allspice shrubs have an upright, rounded growth habit. They grow vertical stems or suckers in the spring, but do not spread aggressively.
The bark, leaves, and flowers often, but not always, have a fruity or spicy aroma.
From spring to midsummer, flowers bloom on old and new wood.
Quick Look
Common name(s): Carolina allspice, sweetshrub
Plant type: Deciduous shrub
Hardiness (USDA Zone): 4-9
Native to: Southeastern United States
Bloom time / season: Spring to midsummer
Exposure: Full sun to partial shade
Soil type: Organically rich loam, well-draining
Soil pH: 5.0-8.0, slightly acidic to slightly alkaline
Time to maturity: 2-5 years
Mature size: 6-10 feet tall, 6-12 feet wide
Best uses: Hedges, specimens, naturalizing, understory
Taxonomy
Order: Laurales
Family: Calycanthaceae
Genus: Calycanthus
Species: Chinensis, floridus, occidentalis
They have a spiral arrangement of tepals – modified leaves that resemble petals. Cultivated varieties have expanded the palette to include additional red and white hues.
In autumn, the elliptical green leaves shade yellow and hard pods form, accenting the bare winter branches.
Carolina allspice is deer and fire resistant and tolerates some drought and flooding.
Because it tolerates light shade, C. floridus is an excellent candidate for understory placements beneath the dappled shade of deciduous trees.
It’s also an outstanding standalone specimen in drifts and borders. Use it as a hedge to define a property perimeter or soften the hard edges of a building’s foundation.
Carolina allspice makes an excellent privacy screen, and its fragrance is appealing beside walkways and patios.
This versatile ornamental shrub is sure to please in settings ranging from woodland clearings to native plant and shade gardens.
You’ll find several recognized varieties of C. floridus, including:
- C. floridus var. glaucus, with smooth twigs and leaf undersides
- C. floridus var. floridus, which has fine hairs
- C. floridus var. purpureus, with burgundy foliage
The other species in the Calycanthus genus include:
- C. chinensis, or Chinese sweetshrub, suited to Zones 6 to 8 with pinkish-white flowers.
- C. occidentalis, or western sweetshrub, native to California and hardy in Zones 6 to 9 with red blooms.
There is ongoing debate about a potential fourth species, the so-called Georgia sweetshrub (C. brockianus), with green flowers.
Some argue it’s simply a green variant of C. floridus. Similar greenish forms of C. occidentalis have also been observed.
Botanists generally agree that the Calycanthaceae family dates back to the Cretaceous Period.
The flowers of that time relied on beetles, not bees, for pollination and that’s still the case with C. floridus, which is primarily pollinated by sap beetles (Nitidulidae).
Sweetshrub species have a long history in American herbal medicine.
From 1722 to 1726, botanists from Oxford University collected sweetshrub samples for their plant collection well before the genus was officially named.
Swedish biologist Carl Linnaeus formally named C. floridus in 1759, making it the first and, for a time, only species in the genus.
By the late 1800s, researchers discovered that Calycanthus plants contain calycanthine, a toxic alkaloid, making them unsuitable for consumption by people or animals.
Today, essential oils extracted from Calycanthus are used in perfumery.
How to Grow
Hardy in USDA Zones 4 to 9, Carolina allspice handles a wide range of conditions.
It tolerates both heat and cold well, as well as brief flooding and some drought. It performs best in climates with moderate humidity and regular rainfall.
Give it plenty of room, sunlight, and well-draining soil, and you’ll enjoy years of lush foliage and fragrant flowers.
Expect a height of six to 10 feet and a spread of six to 12 feet, and allow a minimum of three to five feet between shrubs.
Light
Carolina allspice does best in full sun, where it can develop a dense growth habit and bloom abundantly.
The shrub can tolerate partial shade, but expect fewer flowers and leggier growth. Aim for at least six hours of direct sunlight per day.
Soil
This shrub prefers organically rich loam but is adaptable to a range of soil types, including clay.
The soil must be well-draining. Aim for a pH between 5.0 and 8.0, slightly acidic to slightly alkaline.
Before planting Carolina allspice, loosen the soil to help young roots establish more easily. Avoid low spots where water may pool, which could lead to root rot.
Water
Keep the soil evenly moist during the first growing season, supplying about an inch of water per week in the absence of rain.
Once established, Carolina allspice can handle short dry spells but still benefits from supplemental watering during extended periods of drought.
Apply a two- to three-inch layer of mulch around the base of the shrub, keeping it a few inches away from the stems.
This helps retain soil moisture and as a bonus keeps weeds down!
Fertilizing
In nutrient-rich soil, fertilizer is rarely necessary for Carolina allspice. If you’re working with poor soil, you can apply a balanced, slow-release fertilizer in early spring before budding or in fall after leaf drop.
A product with an NPK ratio of 10-10-10 is ideal.
Alternatively, an application of compost or well-rotted manure around the root zone in spring will give it a nice boost.
Cultivars to Select
If you want to grow the species plant, you can often find sweetshrub available at nurseries and garden centers.
As discussed, C. floridus is suited to Zones 4 to 9. Its mature dimensions range from six to 10 feet tall and six to 12 feet wide.
Carolina allspice, aka sweetshrub, is available from Nature Hills Nursery in #3 containers.
As mentioned, in addition to the species plant, there are numerous hybrids available. Here are a couple to whet your appetite:
Aphrodite
‘Aphrodite’ is a hybrid sweetshrub between C. chinensis and C. occidentalis that offers noticeably longer pedicels or flower stems, bearing large bold red, magnolia-like blooms with yellow centers.
It grows best in Zones 5 to 9.
A vigorous rebloomer, ‘Aphrodite’ delights throughout the growing season. Expect mature dimensions of six to eight feet tall and wide for a substantial display.
‘Aphrodite’ is available from Proven winners via Home Depot.
Hartlage Wine
‘Hartlage Wine’ is a cross between C. floridus and C. chinensis. It is best suited to Zones 5 to 9 and prized for its stunning maroon sepals fading to wine-red.
Richard Hartlage first crossed the two in 1991 in North Carolina State University’s JC Raulston Arboretum. Mature heights are eight to 10 feet with an equal spread.
Maintenance
Even low-maintenance shrubs like Carolina allspice benefit from occasional pruning.
In early spring, you will likely see suckers emerging near the base of the main stems. If you’re growing the plant as a specimen or want to maintain a tidy shape, cut these back at the soil line.
But if you’re aiming for a naturalized look or creating a hedge, feel free to let them grow.
You should also prune as needed to remove any dead, damaged, or diseased wood, and trim branches that rub against each other.
This kind of selective pruning can be done at any time during the growing season.
Carolina allspice is hardy, but it can experience some winter dieback, especially at the tips of branches exposed to wind or deep freezes.
Remove any winter-damaged growth in early spring to encourage healthy new shoots.
If your shrub becomes too dense, you can thin it out by pruning up to one-third of the overall volume. This helps to maintain balance and improve airflow.
The ideal time for this type of pruning is right after the flowers finish blooming. Pruning too late in the season will likely result in fewer buds for next year.
Propagation
Carolina allspice is easy to propagate at home using a variety of methods, including from seed, transplanting suckers, softwood cuttings, and ground layering.
Let’s explore your options.
Seeds
Seed propagation is the slowest method and not all seeds are likely to be viable. Additionally, starting from seed will not produce a clone of the parent plant.
If you have a shrub already, you can collect seeds from the dry rattly pods in the fall. The pods are hard and require pressure to crack them open to retrieve the seeds inside.
In the colder end of the shrub’s hardiness range, sow them immediately. They need to experience cold winter dormancy to jumpstart sprouting the following spring.
In warmer areas, or if you prefer, you can use artificial cold stratification.
Here’s how:
Place dry seeds in a plastic ziptop bag, with all the air squeezed out. Some gardeners add sphagnum peat moss, which raises the risk of rotting and is best avoided.
Place the bag in the refrigerator’s main compartment for three months.
After chilling, bring the bag to room temperature before opening it.
Scarify the seeds lightly with a nail file, then soak them overnight in tepid water.
The next day, dry them on a paper towel and sow one or two seeds about half an inch deep in three-inch pots filled with potting medium.
Place the containers in full sun.
Keep the soil moist but not soggy during germination.
When the seedlings sprout their first true leaves, thin them to one per pot.
After the last frost date for your region, transplant outdoors as discussed below.
Suckers
As mentioned, suckers grow up beside the shrubs in early spring. You can dig these up and plant elsewhere.
Use a long-handled shovel to dig around and six to eight inches below a clump of suckers.
Lift the entire clump of earth. Transplant the suckers as desired.
Softwood Cuttings
Carolina allspice roots easily from softwood cuttings, the tender new growth.
To do this, select a fresh, leafy stem and cut a section six inches from the tip, making your cut at a 45-degree angle.
Fill a six-inch container three-quarters full of potting medium.
Pinch off all of the leaves except a few at the tip.
Dip the cut end in rooting hormone powder.
Use a pencil or chopstick to make a three-inch hole in the center of the medium.
Push the cut stem gently into the hole and tamp the soil around it.
Water well, place in full sun, and keep the medium evenly moist.
New foliage indicates successful rooting, at which point you can transplant outdoors.
Ground Layering
Ground layering is the easiest way to start a new shrub.
In the spring, select a flexible, low, woody branch that bends readily to the ground.
About six inches from the leafy tip, girdle the bark in a two-inch strip about six inches from the tip, just deep enough to penetrate the outer bark layer.
Press the barkless section to the ground. Note where it touches and make a shallow depression in the soil and cover it with a mound of soil four to six inches deep.
Place a rock or brick on top of the mound.
By the following spring, roots should form at the wound. Cut the new plant free from the parent and transplant.
Transplanting
Whether you’ve grown a plant from seed, divided a sucker, rooted a cutting, or layered a branch, the transplanting process is the same.
Prepare a planting hole twice as wide and twice as deep as the root mass. Work the soil until it is friable and free of debris.
Note how deeply the plant sits in its original container. Replicate this depth in the ground. Position the plant so the crown sits at or just above ground level.
Tamp the soil firmly and water in well.
Managing Pests and Disease
Calycanthus is not prone to pests or disease. However, you may encounter thrips.
These sapsucking pests favor hot, dry conditions and leave telltale silvery trails on the foliage. Treat infestations with organic neem oil.
Shrubs grown in poorly draining soil may succumb to root rot caused by soilborne Phytophthora or Pythium pathogens.
Symptoms include stunting, wilting, and yellowing. A fungicidal soil drench may prove successful in the early stages.
You may be able to rescue an affected shrub by unearthing it, pruning off the rotten roots, washing the remaining roots, and replanting it in fresh soil.
Be sure to sanitize your pruners and garden shoes after use.
Plant in well-draining soil and avoid overwatering to minimize the risk of rotting.
A Valuable Ornamental Shrub
If you’re looking for a hardy, low-maintenance ornamental shrub, Carolina allspice is a standout choice.
It offers year-round appeal, thrives in a range of soil types, and contributes to landscape diversity as a native species.
Where will you plant your new shrub to take advantage of all it has to offer? If you already grow Carolina allspice, please tell us about your experience in the comments section below.
And if you’d like to read more about shrubs for the home landscape, we recommend the following guides next:
