Cape Jasmine (Gardenia jasminoides)

Gardenia jasminoides is an evergreen shrub with unique, glossy evergreen leaves and stunning flowers. The sophisticated, matte white flowers are often used in bouquets. The exceptional beauty of this ornamental plant has made it a popular and highly appreciated plant amongst gardeners and horticulturalists.

Common nameCape Jasmine, Cape Jasmine Gardenia, Cape jessamine, Gardenia
Botanical nameGardenia jasminoides
FamilyRubiaceae
Speciesjasminoides
OriginSouthern China, Taiwan. Japan, and Vietnam
Life cyclePerennial
Plant typeHouseplant
Hardiness zone7, 8, 9, 10, 11
SunlightDappled Sunlight
MaintenanceHigh
Soil conditionClay
Soil phAcid
DrainageWell-Drained
Growth rateMedium
Spacing3 ft. – 6 ft.
Harvest timeFall
Flowering periodSpring
Height4 ft. – 8 ft.
Width4 ft. – 8 ft.
Flower colorCream, Tan
Leaf colorGreen
Fruit colorOrange
Fruit typeBerry
Fruit benefitShowy
Flower benefitFragrant
Garden styleAsian Garden
UsesContainer

I. Appearance and Characteristics

Gardenia jasminoides, commonly known as gardenia and cape jasmine, is an evergreen flowering plant in the coffee family Rubiaceae. It is native to parts of South-East Asia. Wild plants range from 30 centimetres to 3 metres (about 1 to 10 feet) in height. They have a rounded habit with very dense branches with opposite leaves that are lanceolate-oblong, leathery or gathered in groups on the same node and by a dark green, shiny and slightly waxy surface and prominent veins.

It has been in cultivation in China for at least a thousand years, and it was introduced to English gardens in the mid-18th century. Many varieties have been bred for horticulture, with low-growing, and large, and long-flowering forms.

Cape Jasmine (Gardenia jasminoides)
J20160530-0002—Gardenia jasminoides John Rusk CC BY 2.0

Gardenia jasminoides is a shrub that ranges from 30 cm to 3 m (1–10 ft) high in the wild, with cylindrical to flat branches that at first are covered with caducous hairs that fall early, leaving the branch smooth. The leaves are in opposite pairs or rarely in groups of three along the branches. They are either subsessile (almost without a petiole) or on short 0.5–1 centimeter (0.2–0.4 inches) petioles. The leaves themselves are 3–25 cm (1.2–9.8 in) long by 1.5–8 cm (0.6–3.1 in) wide and can be oblong-lanceolate, obovate-oblong, obovate, oblanceolate, or elliptic in shape. Their upper surface is smooth and shiny, or slightly hairy along the primary veins, while the undersurface is sparsely hairy to smooth. Each leaf has 8 to 15 pairs of secondary veins. The flowers are solitary and terminal, arising from the ends of the stems.

The white flowers have a matte texture, in contrast to the glossy leaves. They gradually take on a creamy yellow color and a waxy surface. They can be quite large, up to 10 cm (4 in) in diameter, loosely funnel-shaped, and there are double-flowered forms. Blooming in summer and autumn, they are among the most strongly fragrant of all flowers. They are followed by small and oval fruits.

II. How to Grow and Care

Sunlight

Indoor potted gardenias prefer bright light but not direct sunlight, especially during summer. Placing them in a sunny window that gets afternoon shade is best. Garden gardenias grow best planted in a partially shaded location. Some sun, with afternoon shade, works well here, too.

Temperature and Humidity

This shrub holds up in humid temperatures, preferably a humidity level of around 60%, which wards off spider mites who take over gardenias in dry conditions. Since gardenias need humid conditions to flourish, remember to water or mist your gardenias if there is a prolonged drought.

During their growing and blooming season, day temperatures between 65ºF and 70ºF and night temperatures between 60ºF and 65ºF are ideal. Gardenias can’t tolerate cold temperatures below 15ºF and may get damaged or die if these cold temps linger. There are many varieties now, like ‘Frostproof,’ that can be grown in Zone 7 where temperatures can dip to 10ºF in the winter.

Watering

Cape Jasmine (Gardenia jasminoides)
Gardenia jasminoides in Mount Yagi 2008-06-13 Alpsdake CC BY-SA 3.0

Cape jasmine likes consistent moisture but doesn’t tolerate soggy soil. It requires regular and thorough watering; don’t let the soil dry out completely. During hot spells, Cape jasmine should be watered more often. The same goes for container plants that need a more frequent watering schedule.

Soil

Gardenias are acid-loving plants, preferring soil with a lower pH. Traditional potting mixes with a peat base usually meet this criterion. When planted outdoors, it’s best to test the soil’s pH and amend it as needed. Mixing a teaspoon of agricultural sulfur into the planting hole may help lower soil pH.

Fertilizing

Feed garden gardenias in mid March and then again in late June using an acid-rich fertilizer. Refer to the product’s instructed amounts and mix the fertilizer directly into the soil or dilute it with water. It’s best to use slightly under the recommended dosing to avoid over-fertilization. Stop feeding your gardenias in the fall to inhibit new growth before dormancy.

Container plants can be fed about every three weeks with an acidifying fertilizer similar to those used on azaleas or camellias. Organic gardeners prefer blood meal, fish emulsion, or bone meal. Refer to product recommendations on amounts and test the soil’s pH regularly.

Pruning

Prune gardenias after the plants have stopped blooming, removing straggly branches and spent blooms to your liking. However, gardenias don’t need to be pruned every season; this variety does fine with an every-other-year cutback. When pruning, use sharp garden shears to shape back the green and brown wood. Gardenias set buds on new and old wood, so cutting either is fine.

Propagation

Gardenias are best propagated by rooting stem cuttings in the early spring, but gardeners find it more convenient to propagate from cuttings taken during pruning. Whichever you choose, give the new plant sufficient time to establish roots and grow before winter dormancy.

Cape Jasmine (Gardenia jasminoides)
Gardenia jasminoides bud …..DSC03326a SantaRosa OLD SKOOL CC BY 2.0

Here’s how to propagate gardenia from cuttings:

  • Gather garden shears, rooting hormone, 3-inch pots, plastic bags, stakes, and potting soil that contains perlite.
  • Take a 3- to 5-inch cutting off a stem tip (preferably on green wood) just below a leaf node. Remove the lower leaves, leaving only the top set of two.
  • Prepare pots with moist potting soil and poke a hole into the center of the soil.
  • Dip the cut end of the stem in rooting hormone, and then plant the stem in the hole. Backfill the hole.
  • Place plastic bags around the pots and prop them with garden stakes.
  • Place your pots in bright, indirect sunlight in a room where the temperature is at least 75 F. Keep the soil moist until good roots form (about four to eight weeks).
  • When temperatures allow, transplant the small gardenias into your garden.

How to Grow from Seed

Gardenias can be propagated by seed, but it involves a long process that can take two to three years before the plant flowers. Collect and clean seeds from dried seed pods and then dry them for three to four weeks in a sunny window.

Plant the seeds in a mixture of perlite and peat moss, barely covering them with about 1/8 inch of potting mix. Keep the seeds moist and out of the sunlight until they sprout (about four to six weeks). When the seedlings are several inches tall, transplant them into pots filled with peat-based potting soil, and continue growing them in a sunny indoor location.

Transplant the seedlings to your garden once they have at least three sets of leaves. Continue caring for the baby plants until they reach maturity.

Potting and Repotting

Gardenias do well outdoors in containers and can even be pruned into topiaries.

For first-time potting, use a container slightly larger than the one from the nursery. Like growing gardenias in the ground, acidic, well-draining, evenly moist soil is required. But for containers, use a basic potting mix, which is slightly acidic and well-draining. Add an acid plant fertilizer to the soil, and continue to feed once a month. Repot gardenias every two to three years.

Overwintering

The tropical gardenia will die in temperatures below 15 F and has difficulty dealing with winter frost. While USDA Zones 8 through 10 usually don’t experience this type of weather, it’s still a good idea to ensure the warmth of your plant.

Provide ample mulch to the base of the plant to insulate its roots. You can also create a frost blanket on nights that are suspect. Frost cloth can be purchased at any nursery, or you can use a cardboard box, a bedsheet, or a 5-gallon bucket for this purpose.

Pests and Diseases

Common Pests & Plant Diseases

Insects, especially scales, aphids, spider mites, mealybugs, and whiteflies, can all affect the health of your gardenia, giving it its “high-maintenance” label. To control bugs, you can use a variety of horticultural oils and soaps, as well as organic products. Whichever you choose, arm yourself ahead of time for frequent infestations.

Gardenias can also suffer from powdery mildew, leaf spot, dieback, anthracnose, and sooty mold, some of which can be treated with fungicides. In many instances, however, affected plants must be removed and destroyed, making this plant best suited for a gardener who can devote the time to get the right conditions.

Common Problems With Gardenia

Cape Jasmine (Gardenia jasminoides)
Gardenia jasminoides Tatters ✾ CC BY 2.0

Maintaining the ideal conditions for this plant is the ultimate challenge for gardeners. So, unless you live in a climate that can help the plant achieve perfect harmony, you may want to forego the beautiful gardenia for something more easygoing yet equally rewarding. If you’re up to the challenge of growing gardenias, though, here are some potential issues to look out for.

Bud or Leaf Drop

Cold temperatures, inconsistent watering, poor soil drainage, and insufficient light can cause bud and leaf drop on gardenias.

Yellowing Leaves

Unsuitable environmental conditions like less than ideal temperatures or poor light can also cause yellowing leaves. Ultimately, any stress on the plant opens the door for pests, fungi, and diseases to move in.

III. Uses and Benefits

  • Ornamental uses

Cape jasmine is such a popular garden plant that it has received the Royal Horticultural Society’s prestigious Award of Garden Merit. The plant’s fragrant, showy flowers are its standout feature, but attractive evergreen leaves offer year-round garden interest. It is great as a specimen plant, hedging, or as a cut flower. This isn’t a frost-hardy species and is, therefore, best-suited to tropical gardens or indoor growth. Colorful annuals such as blue torenia and wax begonias partner well with these white flowers.

  • Medicinal uses

Shishihakuhito is a Chinese herbal medicine mainly composed of gardenia fruit and is used to treat atopic dermatitis. It inhibits Immunoglobulin E (IgE) mediated histamine release.

In 2020, a case of someone who had developed blue-gray discoloration of the skin as a result of chronic intake of gardenia fruit extract was published.

  • Culinary uses
Cape Jasmine (Gardenia jasminoides)
Gardenia jasminoides fruit Alpsdake CC BY-SA 3.0

Gardenia flowers can be eaten raw, pickled, or preserved in honey. In China, the petals are used in tea for their aroma, while a yellow-red dye used in textiles and sweets has been extracted from the pulp of the fruit. Gardenia jasminoides fructus (fruit) is used in traditional Chinese medicine to “drain fire” and treat certain febrile conditions. It has anti-inflammatory and antipyretic effects.

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