How to Grow California Sweetshrub

California Sweetshrub Flower Flickr peganum

peganum / Flickr / CC BY-SA 2.0

The California sweetshrub (Calycanthus occidentalis) is a deciduous shrub that has its origins in that western state, hence its botanical name. It features deep maroon flowers that are richly fragrant. Curiously, like magnolia trees and shrubs, the moderate-growing California sweetshrub is pollinated by beetles. It has green leaves and blooms that have a spicy aroma.

This shrub is included in the Calycanthaceae family. The other species in this genus is the Carolina sweetshrub (Calycanthus floridus). The species name occidentalis means western and in this case, indicates that it comes from the western part of the United States.

At maturity, the plant will be 4 to 15-feet tall and wide, naturally forming into a rounded shape. California sweetshrub should be planted in the fall or early spring.

Botanical Name Calycanthus occidentalis
Common Name California sweetshrub, western spicebush, California spicebush, California allspice, spicebush, western sweet shrub.
Plant Type Deciduous shrub
Mature Size 6-12 ft. tall, 6-12 ft. wide.
Sun Exposure Fun sun to part shade
Soil Type Loamy
Soil pH 5-8, neutral to acidic to alkaline
Bloom Time June-August
Flower Color Dark red, purplish brown
Hardiness Zones 6-9 (USDA)
Native Area Southwestern United States
Toxicity Toxic to humans and animals

California Sweetshrub Care

The leaves bear a pleasant scent and are the inspiration for the name spicebush. The fruits are achenes that are aggregated within a capsule.

Deer tend to stay away from this shrub so it is a good choice if they visit your garden often. You can use this species as part of a landscape designed to control erosion alongside natural water features like riverbanks.

Light

You can plant sweetshrub in most locations since it can handle full sun to full shade.

Soil

California sweetshrub prefers loamy soil but can be also planted in clay, silt, and sand. It's very versatile.

Water

California sweetshrub prefers moderate water, moderate humidity, to keep it moist but not oversaturated.

Temperature and Humidity

California sweetshrub may be planted in USDA zones 6-9. The common name is apt since this is indeed native to California.

Fertilizer

This shrub has only mild fertilization needs; use a formula for trees and shrubs.

Is California Sweetshrub Toxic?

All parts of California sweetshrub are poisonous to humans and animals—especially the seeds—because they contain calycanthine, an alkaloid very much like strychnine.

Symptoms of Poisoning

Both humans and animals may exhibit dangerous neurological symptoms upon ingestion of California sweetshrub. Call poison control or your veterinarian immediately.

Pruning

This species tends to send out suckers. You can help control them by keeping the shrub healthy and pruning away any that appear with clean, sharp gardening shears.

Propagating California Sweetshrub

Propagation may be done by taking softwood cuttings. To do so: Using a clean, garden shear, take 3 to 5-inch cuttings from your sweetshrub early in the day. Cuttings should have at least two leaf nodes, with one of your cuts being below the second leaf node. Gently remove the lower leaves, and dip the ends in rooting hormone. Tap off excess and place each cutting into a seedling tray filled with a 60% perlite, 40% soilless potting mix. Place stakes in the corners of each section, then slide the entire thing into a zip-top bag in indirect sun. Water regularly, but not too much. When the cuttings have created a hearty amount of roots—about six weeks later—they can be replanted outside in your garden.

How to Grow California Sweetshrub From Seed

California sweetshrub can be propagated by seed but their seedlings may vary from the parent plant, in both aroma and appearance. If you insist, make sure to use fresh seeds, as older ones might not sprout. Seeds do well if they are first stratified, which you can do in your fridge by wrapping them in damp moss or paper towels, popping them in a zip-top bag, and waiting several months before placing them in a potting medium.

Conversely, California sweetshrub seeds do very well if they are planted directly in the ground right near where you collected the seeds. They should be planted immediately and will germinate quickly.

Potting and Repotting California Sweetshrub

California sweetshrub does well in containers, and it's fun to be able to move it around your garden so you can enjoy its fragrance wherever you are spending your time. It can be bought from nurseries, and ships bare-rooted. Plant your California sweetshrub in a loamy soil, and make sure your container has good drainage holes.

Common Pests and Diseases

California sweetshrub isn't plagued by most pests or diseases. That said, it can be affected by bacterial crown gall which causes wart-like growths near the stem. There’s no treating this disease, so if your sweetshrub is stricken with it, you must remove and destroy any affected plants (and don't replant in the same location).

Powdery mildew is an occasional problem and can be treated with organic neem oil.