Mexican orange (Choisya ternata) is a plant species native to the southern United States and Mexico. The Latin name Choisya ternata references the Swiss botanist Jacques Denis Choisy. The mexican orange is known for its highly abundant and fragrant flowers.
I. Appearance and CharacteristicsÂ
Choisya ternata is a species of flowering plant in the family Rutaceae, known as Mexican orange blossom or Mexican orange. Choisya ternata originates from Mexico. It is drought tolerant, preferring well drained soils.
Choisya ternata is an evergreen shrub, growing up to 3 m (10 ft) in height. Its leaves have three leaflets (hence ternata) and are aromatic, releasing a smell reminiscent of basil when crushed. The white flowers are scented, appearing in spring (sometimes with limited repeat flowering in autumn).
Choisya ternata is widely grown as an ornamental shrub in suitable climates. It tolerates temperatures down to −10 °C (14 °F) but is severely damaged by temperatures lower than −15 °C (5 °F). It responds well to pruning and shaping.
In addition to the species, a number of cultivars are grown, including the golden-leaved C. ternata ‘Lich’ (usually sold under the name Sundance), and the inter-specific hybrid C. ‘Aztec Pearl’ (C. dumosa var. arizonica × C. ternata). The species and these two cultivars have gained the Royal Horticultural Society’s Award of Garden Merit.
Many quinoline alkaloids have been isolated from leaves of C. ternata. C. ternata contains an alkaloid (ternanthranin), a volatile simple anthranilate, that was shown to have pain-killing effects in mice.
II. How to Grow and Care
Sunlight
A full sun to partial shade location is recommended for Mexican orange, but it will survive in full shade, as well. Shadier conditions will result in fewer flowers. Ideally, give it a spot with full sun in the morning, but with some protection from the hot afternoon sun.1
Temperature and Humidity
Mexican orange is considered hardy in USDA zones 7 to 10, but it has been known to survive occasional temperature dips down to as low as 5 to 10 degrees Fahrenheit. However, reliable flowering requires an environment that never falls below 27 degrees. Ideal winter temperatures are 40 to 50 degrees.
Watering
Soil
This plant performs best in soil that is fertile and humusy, well-draining and slightly acidic. But it will not mind neutral or even slightly alkaline soils.
Fertilizing
Fertilize in the spring with compost or well-rotted manure. New plants will require extra phosphorus to develop a strong root system—this can be added to the bottom of the planting hole. In warmer climates, an extra fall fertilizer feeding is recommended.
Planting Instructions
Pruning
Pruning is not required for the health of this shrub, but you can trim it to maintain the desired shape and size. Occasionally some leaves will experience dieback, and in those cases, cut back the plant—it will tolerate pruning all the way to the ground, if necessary. Some gardeners choose to prune the plant back after flowering to achieve a more formal appearance. This kind of light pruning immediately after the plant flowers often stimulates continued sporadic flowering through the summer and into early fall.
Propagation
Mexican orange can be grown from seed or propagated from semi-hardwood cuttings, but be aware that many varieties sold in garden centers are trademarked cultivars that cannot be legally propagated by any means. However, if you have a pure species plant or a non-trademarked cultivar, you can propagate your Mexican orange by rooting semi-hardwood cuttings. Here’s how to do it:
- In mid to late summer, use sharp pruners to clip a six-inch semi-hardwood cutting (mature, but not yet fully hard).
- Remove the lower pair of leaves, retaining just one or two pairs of leaves at the top of the cutting.
- Dip the bottom of the cutting in powdered rooting hormone, and plant the cuttings in a porous seed starter mix (or a mixture of potting mix and sand).
- Place the cutting in a bright location but out of direct sunlight, and keep the potting medium just barely moist. Within a few weeks, the cutting will develop roots and new growth should begin.
- Move the rooted cutting outdoors and continue growing, repotting as necessary. It’s best to grow the cutting for a full year before transplanting into the garden. In winter, protect your plant from cold—ideal winter temperatures are 40 to 50 degrees Fahrenheit.
How to Grow From Seed
Propagating Mexican orange from seed is slow and not always successful, so it is rarely done except by greenhouse professionals. If you want to try it, sow the tiny seeds from the fruits very shallowly in seeding flats. Keep the seedling flats moist in bright greenhouse conditions (but out of direct sunlight) until they sprout. When large enough to handle, the seedlings can be transplanted into individual pots filled with potting mix. The seedlings are typically grown for a full year in a greenhouse (or indoors) before they are ready for outdoor pots or planting in the garden.
Potting and RepottingÂ
In cooler regions of the country, a great option is to grow this shrub in a container that can be moved to a more sheltered location when the weather cooled down. Choose a well-draining pot (any material will do) that is at least twice as large as the nursery container. Standard commercial potting mix works fine for container-grown shrubs. Mixing in some sand can help with drainage. This is a fast-growing shrub, so repotting will be necessary every few years.
When grown in pots, this species might be attacked by Pythium root rot, but is otherwise disease-free. Mexican orange grown in containers will need more frequent watering and feeding than garden-grown plants.
Overwintering
These shrubs require almost no extra care for winter other than offering a fall fertilizer feeding. Move potted plants to a spot that is sheltered from harsh, cold winds. If you live in a cold-winter zone, move your potted plant indoors to a sunny location.
Pests and Diseases
Mexican orange is free of almost all plant diseases, but it can be susceptible to red spider mites (controlled with neem oil or another horticultural oil) and snails (which can be picked off or baited).
How to Get to Bloom
Mexican orange typically blooms with large clusters of fragrant white flowers for several weeks in early or late summer. A light pruning immediately after they are finished flowering can stimulate sporadic additional flowers through the summer and into early fall. If the plant does not flower, it is usually for one of these reasons:
- Not enough sun: Although these plants tolerate partial shade, they need a full six hours of sunlight, preferably in the morning, to generate ample flowering.
- Pruning at the wrong time: Mexican orange blooms on old wood developed during the previous growing season, so if you prune it in winter or too early in the spring, you will be sacrificing the flower buds. If pruning is necessary, do it immediately after flowering, which provides plenty of time for the growth that will provide the next season’s flowers.
- Bad timing for fertilizer: Mexican orange is best fed with compost in the spring, then a light feeding in the fall. Too much nitrogen in the spring will stimulate green growth at the expense of flowers.
- Poor soil: Mexican orange requires rich, humusy soil. If your plant is not blooming, make sure to blend in compost in the spring and feed with fertilizer it in the fall.
- Plants are too young. It can take as long as three years for a Mexican orange plant to mature into a flowering plant, especially if it is started from seed. If a potted nursery plant doesn’t flower the first year, it might simply be a young plant that needs another season to mature.
III. Uses and BenefitsÂ
Mexican orange grows in warm climates. It is prized for its fragrant, pale flowers and glossy leaves. It is an attractive hedge or side-border plant. The plant is grown as a focal point in a garden bed or as foundation plant. It is frequently paired with California lilac, Iris, or Shasta daisies.
