Wintersweet (Chimonanthus praecox) is a large multi-stemmed deciduous shrub with glossy oval leaves. It produces bursts of pendulous yellow flowers as the foliage drops in fall or winter. Native to China, this is an excellent winter-flowering shrub for zones 7 to 9 climates where winters are fairly moderate. Throughout most of the year, when other plants are in the spotlight, wintersweet is overlooked. The real show begins when the foliage falls away and reveals the stark gray stems that soon produce the waxy, translucent yellow flowers along each branch.
Wintersweet is a slow-growing shrub that can take as much as 15 years before it reaches flowering maturity. It is normally planted as a container-grown nursery specimen or ball-and-burlap plant in spring or summer.
Chimonanthus praecox is sometimes erroneously described as a toxic plant. But this is because it is often confused with another plant also sometimes called wintersweet, Acokanthera spp. But while Acokanthera has well-documented toxicity, C. praecox is not included on any official lists of plants toxic to humans or pets. However, there are documented cases of C. praecox causing toxicity in grazing goats.
|Common Name||Wintersweet, Japanese allspice|
|Botanical Name||Chimonanthus praecox|
|Plant Type||Deciduous shrub|
|Mature Size||10-15 ft. tall, 8-12 ft. wide|
|Sun Exposure||Full, partial|
|Soil Type||Fertile, moist but well-drained|
|Soil pH||Acidic to alkaline (6.0-8.0)|
|Flower Color||Yellowish with purplish-brown centers|
|Hardiness Zones||7-9 (USDA)|
|Toxicity||Possibly toxic to goats|
Winterswee is best planted from an established nursery plant since plants grown from seeds can take a decade or more before blooms will appear. Once a suitable site is selected, take care to plant wintersweet correctly. It should go in a hole twice as wide as the root ball or container is deep, and the fill soil should be well amended with compost, peat, or another organic material.
Once it is planted, mulch the shrub's root zone to a depth of 3 inches out to the drip line, but take care to keep the mulch material from touching the trunk. This will aid in moisture retention while the plant is watered deeply until it is established—about one full season.
To encourage your wintersweet to produce more blooms, plant it in a location that receives full sun.
Wintersweet thrives in moist, fertile, well-drained soil. It is not fussy about pH, growing equally well in acidic, neutral, or alkaline soils.
Water generously until established. Once established, regular watering is still needed during the summer and in cases of high temperatures or drought.
Temperature and Humidity
Wintersweet is hardy in USDA zones 7 to 9, although there are cases of it growing in zone 6 in protected areas.
Fertilizer is not needed but can help with flowering. A 5-30-5 liquid fertilizer will help produce more blooms on your wintersweet.
Types of Wintersweet
There are two popular cultivars of C. praecox:
- 'Grandiflorus' offers sweetly-scented blooms and butter-yellow flowers.
- 'Luteus' has fragrant flowers and dark-green leaves.
In addition, there is a related species to consider. Chimonanthus nitens' features evergreen leaves and white flowers but lacks the overpowering scent of C. praecox.
With established plants, wintersweet should have seasonal maintenance performed each winter after the blooms have fallen off. The shrub’s oldest stems should be cut down to almost ground level to ensure new, healthy growth during the coming year. This will help to bolster the number of flowers that come on next winter’s stems and keep the shrub at a manageable size and in good health. This shrub looks best if allowed to cascade in a natural fashion, so don't attempt to shape it too strictly.
Since wintersweet grown from seed can take nearly 15 years to flower, the best way to propagate wintersweet is by creating stem-cuttings. To do so:
- Using clean, sharp garden shears, create cuttings by snipping off 5-inch lengths, about 2-inches below a flower node on a healthy softwood stem.
- Dip the end of the cutting in rooting hormone.
- Place each stem into a terra-cotta pot filled with seed-starting mix, right up to the nodes. Keep moist.
- Within about six weeks should notice roots. When the cuttings are solidly rooted, transplant them into the garden.
Wintersweet can also be propagated by layering—the process of staking down a flexible branch into the soil, waiting for it to develop its own roots at the point of soil contact, then carefully freeing the new root system and stem to plant in another location.
How to Grow Wintersweet From Seed
Mature seeds of wintersweet can be planted in small pots filled with potting mix and placed in an outdoor cold frame to germinate and sprout. But you'll need to be patient, as seed-sown plants can take 10 years or more before they reach flowering maturity.
Potting and Repotting Wintersweet
Though not common, container culture is possible for these plants, especially in their early years before they grow to an unwieldy size. A large, well-draining container filled with standard potting mix will serve adequately, but potted plants will need to be positioned in a sheltered location to overwinter. These are slow-growing shrubs, so repotting will be needed only every few years, when the plant becomes root-bound in its container.
Young plants may require some winter protection against cold, in the form of a thick layer of mulch over the root zone, and possibly a shield of burlap in zones 6 and 7. After two or three years, the shrub should be mature enough to no longer need this winter protection.
How to Get Wintersweet to Bloom
The bloom time for wintersweet varies a bit, depending on where it is grown. At the northern end of its hardiness range, it typically blooms in February and March, but further south it will bloom in December through January. To encourage wintersweet to bloom, make sure it is adequately fed and watered, and that it gets sufficient sunlight. Yearly pruning will also ensure good blooming.
Untimely frost may kill flower buds and cause poor blooming. The shrub generally recovers and will bloom normally the following year. In borderline climates (zones 6 and 7), it helps to plant wintersweet in a spot protected from harsh winter winds.
Common Problems With Wintersweet
This shrub is largely free of cultural problems, but as it ages, wintersweet may become somewhat sparse and leggy, and often too large for its space. If this happens, perform a severe rejuvenation pruning by eliminating as much as one-third of all older stems after the flowering period is over. Shortening the remaining stems will also force the plant to become denser.
How should I use wintersweet in the landsape?
The plant's location should also be carefully considered. An area where the fragrance can be enjoyed and experienced without effort is a good bet. Along a path, by a door, or around a gateway are great options. Also, think of the visual impact of the translucent yellow blooms, which work best when backlit by the sun. Wintersweet also makes a good specimen shrub for open gardens or shrub borders, and it makes a beautiful addition to winter-interest Japanese gardens.
How long does wintersweet live?
Like many slow-growing shrubs, wintersweet will live for many decades once it is established in a favorable location. Prune it regularly to encourage vitality.
Does wintersweet have good fall color?
While the main appeal of this shrub is its winter flowers, the fall foliage also has an attractive yellow hue.
Does wintersweet have a notable aroma?
It has been said that wintersweet has the most beautiful aroma of any flower, though this lasts for only a month or so. The smell is especially strong during relatively warm winter nights that cause the volatile oils to vaporize. These are usually the last days that the shrub is in bloom, and it is at this point that wintersweet just needs to be breathed in.
Wintersweet Toxicity in Four Goats. New Zealand Veterinary Journal.