Pink jasmine

Identification and origin

Jasminum polyanthum belongs to the olive family, Oleaceae, along with olives and lilacs. It is native to southwestern China and neighboring Myanmar. The French botanist Adrien Franchet described it in 1891; the epithet polyanthum means “many-flowered.”

It is a very vigorous evergreen climber whose slender stems twine around their supports. Planted in the ground in a mild climate, it can reach 19.5–24.5 ft; in a container on a support it usually stays around 9 ft and is kept in check by pruning. The opposite leaves are made up of five to seven pointed leaflets, the end leaflet being the longest; they are dark green above and paler beneath.

The long, pointed, deep pink buds open into white, star-shaped, long-tubed flowers about 1 in across, rosy on the outside. They are carried in branched clusters up to 4 in long and give off an intense fragrance. Bloom is heaviest in late winter in a warm sunroom or greenhouse, and comes more in spring and summer in a cooler spot or outdoors. The small, round black fruits are rarely produced. The species has received the Award of Garden Merit from Britain’s Royal Horticultural Society.

In warm regions it can escape from gardens: it spreads mainly by natural layering and suckering, as its trailing stems root at the nodes. It has naturalized in Australia and New Zealand.

Light

Pink jasmine needs plenty of light to flower. Indoors, set it by an east- or west-facing window in bright filtered light; in winter, a south-facing window gives it the most light. An airy room suits it better than a stuffy corner.

Outdoors, it grows in full sun or part shade, ideally against a south- or west-facing wall sheltered from wind. During the warm season, a potted plant can go outside to a warm, protected spot.

Watering

During growth and bloom, it needs regular watering: the root ball should stay moist but never sit in water. Check by touching the mix; when the surface starts to dry, water until it runs out of the drainage hole, then empty the saucer.

In winter, cut back sharply and give just enough water to keep the root ball from drying out. A pot that feels light and a mix pulling away from the sides are signs of thirst.

Jasmine likes humid air. Mist the foliage and stand the pot on a tray of moist gravel, especially near a heater.

Potting mix

In containers, use a peat-free, soil-based potting mix that holds moisture yet drains well. In the ground, it likes fertile, well-drained soil, whether chalky, loamy or sandy, acidic or alkaline; it even copes with poor soils.

To boost flowering in containers, give a high-potassium liquid fertilizer, such as a tomato feed, during the growing season, following the label rate. Plants in the ground need only a mulch of compost in fall, which keeps the soil moist and insulates the roots; leave a few inches clear around the stems.

Temperature

This is a tender plant that tolerates cool conditions but not frost. Indoors, it does best in a cool setting, around 46–59 °F, such as a sunroom or a bright, frost-free entryway; in winter, a room at 46–50 °F suits it especially well. Do not let it drop below 39 °F. A winter spent too warm encourages aphids.

If you move it outdoors for the summer, bring it back inside before nights fall below 55–59 °F, and avoid leaving it in a cold spot overnight. In the ground it is grown only in mild regions, in USDA zones 8 to 10, where it can lose part of its foliage in winter.

Repotting

Repot when the roots fill the pot, moving it to a container with drainage holes just slightly larger. At the same time, add a sturdy support such as a hoop, trellis or stake. The plant is so vigorous that, from year to year, you will need either to prune it to keep it compact or to give it a larger support.

In a sunroom it can also be trained on a trellis along a wall. Outdoors, plant it in a warm, sheltered spot.

Pruning

Prune right after flowering. Cut flowered stems back to a strong side shoot lower down, and thin out shoots that are overcrowded, damaged, weak or badly placed. Under glass, harder pruning is often needed to keep the plant in bounds.

Pruning once a year keeps the jasmine vigorous, stops it from becoming a tangle of stems and keeps the flowers low enough to enjoy their scent. Wind new shoots around the support as they grow.

Propagation

Cuttings are the easiest method. In spring or summer, take softwood or semi-ripe cuttings, cutting between two nodes; insert them in a light mix and keep them sheltered until they root.

Layering is another option, in fall: bend a stem down onto a pot of mix, pin it in place and wait for it to root before severing it. The plant also produces suckers that can be separated. Seed is possible, but the fruits are rarely produced.

Common problems

• Sticky leaves, distorted shoots: aphids, especially when the winter is too warm.
• Small brown shells on the stems: scale insects.
• White, cottony tufts in the leaf joints: mealybugs.
• Dull, stippled leaves with fine webbing: spider mites.
• Decline of a plant in the ground: honey fungus root rot, rarely.

A symptom can have several causes: check light, watering, temperature and the leaf undersides before acting, and act early, since an infestation is easier to control when it is just starting.

Toxicity

Jasmines in the genus Jasminum are classed as non-toxic to dogs, cats and horses, and no toxicity has been reported for people. As with any houseplant, it is best to keep pets and young children from chewing the leaves.