How To Grow And Care For Gardenias

No plant expresses the South's grace better than the gardenia's fragrant blossoms.

No plant expresses the grace of the South better than gardenia. Intensely fragrant white blossoms contrast beautifully with shiny, leathery dark green leaves. The double forms make for classic corsage flowers, but gardeners struggle to perfect the delicate dance required for these plants to thrive.

Balancing between tropical, humid climates, and damage from too much sunlight, choosing where to plant your gardenia is your first challenge. From there, tending to the variety (and size) of your gardenia plant will require a bit of work, but we have some best practices to follow when adding this flower to your gardening to-do list.

White Gardenia Flowers
© Santiago Urquijo / Getty

Plant Attributes

  • Common name: Gardenia, Cape Jasmine
  • Botanical Name: Gardenia jasminoides
  • Family: Rubiaceae
  • Plant Type: Perennial, Shrub, Evergreen
  • Mature Size: 3- to 8-feet tall and wide
  • Sun Exposure: Full sun, Part sun
  • Soil Type: Organically-rich, Well-drained, Loamy, Moist
  • Soil pH: Acidic (5.0 to 6.5)
  • Bloom Time: Spring, Summer, and sometimes Fall depending on variety
  • Flower Color: White
  • Hardiness Zones: 8-11 (USDA), with some selections in Zone 7
  • Native Area: Asia

How to Care for Gardenias

Where (and When) to Plant Gardenias

According to the Farmer's Almanac, the best time to plant gardenias is fall, or six weeks before the first frost in milder climates, and spring for areas with colder temperatures. Again, here is a decision that every gardener must face when venturing into the new gardenia-growing space as it is dependent on your location.

For larger varieties, gardenias grow as border plants or in areas where they won't compete for the soil's nutrients, be overcrowded, and has room for their roots to spread. Also, you should try not to disturb these plants once in place. Plant them high in the ground or on raised beds, similar to azaleas and rhododendrons, allowing for better drainage and altering soil composition.

Gardenias do well in large pots on decks and patios. Gardeners in cold-winter areas can grow them in cool greenhouses. Unfortunately, they make poor houseplants—they attract mites, mealybugs, and whiteflies.

Light

Try planting gardenias in a place where they can get 4 to 6 hours of sunlight, with some caveats. In warmer climates, avoid the intensity of late afternoon sunlight and choose an area where it can receive only morning to mid-day light. Cooler temperature regions can use a site with full sun.

Soil

Gardenias prefer acidic (5.0 to 6.5), organically rich, and loamy soil that's well-draining. You can amend your soil to increase acidity and add organically-rich materials like compost, manure, ground bark, and sphagnum peat moss.

Water

Although gardenias enjoy sunlight, they can't go too long without proper watering. Gardenias prefer rich, acidic soil, similar to rhododendrons and azaleas, that doesn't stay too wet, so it's a perfect option for Southern gardens.

Temperature and Humidity

This shrub holds up in humid temperatures, preferably a humidity level above 60 percent, 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 65 and 70 degrees and night temperatures between 60 and 65 degrees are ideal. Gardenias can't tolerate cold temperatures below 15 degrees 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 10 degrees in the winter.

Fertilizer

Feed plants every three to four weeks during the growing season—use an acid fertilizer, fish emulsion, blood meal, or even coffee grounds. Feed potted plants just as often and test soil pH levels to maintain good health.

Type of Gardenias

'Aimee' ('First Love')

Somewhat larger shrub than 'August Beauty,' with larger flowers. Spring bloom.

'August Beauty'

It grows four to six feet high and three to four feet wide. Blooms heavily mid-spring into fall—large double flowers.

'Chuck Hayes'

Extra-hardy type, possibly as hardy as 'Klein's Hardy.' It grows to four feet high and wide. Double flowers in summer, heavy rebloom in fall.

'Golden Magic'

It reaches three feet tall and two feet wide in two to three years, eventually larger. Extra-full flowers open white and gradually age to deep golden yellow. Blooms from spring through summer, peaking in mid-spring.

'Grif's Select'

Compact, 3–4 ft. tall and wide; profuse single flowers in late spring and early summer, red seed capsules in fall. Hardy to about 5°F.'Kimura Shikazaki' ('Four Seasons'). Compact plant 2–3 ft. tall. Flowers similar to those of 'Veitchii' but slightly less fragrant. Extremely long bloom season—spring to fall.

'Kleim's Hardy'

It grows from two to three feet high and wide in cold-winter areas—single flowers in summer. Grow in a wind-protected site.

'Miami Supreme'

It grows up to six feet tall and wide, with large double flowers (four to six inches wide) in spring, with periodic flowering through summer.

'Mystery'

Best-known selection. Bears four to five-inch double flowers from mid-to-late spring. It tends to be rangy and needs pruning to keep it neat. It can reach six to eight feet high and wide.

'Radicans' ('Prostrata')

It grows six to 12 inches tall and spreads to two to three feet, with small leaves and inch-wide double flowers blooms in summer. Suitable for small-scale ground cover or pots. Not as cold-hardy or suited to Middle South.

'Radicans Variegata' ('Prostrata Variegata')

It has gray-green leaves with white markings.

'Shooting Star'

Upright grower to six to eight feet tall and wide, with large leaves and single flowers in late spring and early summer.

'Veitchii'

Compact, reliable grower to 3 1/2 to 4 1/2 feet tall and six feet wide. Blooms prolifically from mid-spring into fall (sometimes even during warm winters), bearing double one to 1 1/2-inch flowers.

'White Gem'

At just one to two feet tall and wide, this selection is helpful for edgings, containers, or raised beds, where the fragrance is appreciated even from a single, creamy white summer flower.

Pruning

Remove faded or dying flowers, usually around two-thirds from their initial flourish, to continue seeing blooms. You can prune younger gardenias to adjust their shape or to remove straggly branches and faded flowers.

Propagating Gardenias

The best time to propagate gardenias is in spring. Gardenias can be propagated through the following method:

  • You will need pruners, rooting hormone, a 3-inch pot, potting soil, and perlite.
  • Cut the branch down from the tip, about 5 inches; the stem should preferably be green at this end, called softwood.
  • Remove all but three leaves at the top.
  • To encourage root growth, dip the bottom of the cut stem in root hormone
  • Plant in a pot filled with a mix of potting soil and perlite.
  • Keep the pot in a humid spot, in a spot with indirect sun, and make sure the soil is evenly moist.
  • The cutting will take 4 to 6 weeks to root before it can be transferred to the ground.

Potting and Repotting Gardenia

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 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.

Common Pests & Plant Diseases

Pests

You can control whiteflies, aphids, and other sucking insects with light horticultural oil. Try using an insecticide rinse to wash away the residue left behind.

Root Rot

When the leaves of your gardenia turn yellow, it is a sign that you might have root rot. This damage typically occurs from overwatering or another fungus in the soil, such as powdery mildew. Powdery mildew appears as white spores covering the plant's leaves and can be a recurring problem preventing future growth.

How to Get Gardenias to Bloom

Maintaining healthy gardenias encourages more blooms. Here are some best practices to keep gardenias blooming all season, according to Southern Living Plants:

  • Fertilize gardenias each spring after the last frost, then feed regularly during the growing season.
  • Make sure the soil is evenly moist soil, but don't overwater, which can cause root rot
  • Mulch the roots to help maintain moisture.
  • Gardenias don't need a lot of pruning, but if you need some shaping or want to remove unproductive stems, do so after the blooming period, in early summer, but before the budding period, which starts in late summer and fall.
  • Gardenias bloom in May and June, and the bloomed flowers can last several weeks.
  • To encourage more flowering and maintain a tidier-looking plant, deadhead the spent blooms.

Common Problems With Gardenias

Bud Reductions

There are several reasons why your gardenia might not be blooming to its full potential. Along with insects and disease, improperly managing your plant, such as over or under-watering, can result in the plant's failure. When temperatures, specifically the humidity, drop, it can harm the gardenias.

Black Leaves

When gardenias are infested with aphids or whiteflies, these bugs secrete a sticky honeydew as they feed. Black, sooty mold then grows on the honeydew. Spray your gardenias according to label directions with horticultural oil, making sure to wet both the tops and undersides of the leaves, as well as the stems. This will kill the insects, which will also knock out the moldy honeydew.

Yellow Leaves With Green Veins

If your gardenia has yellow leaves with green veins it is due to a condition called chlorosis brought on by a lack of iron in the soil. Acid soils have plenty of available iron. Alkaline soils do not. Apply garden sulfur to the soil to acidify it or feed with an acid-forming fertilizer like Espoma Holly-tone.

Yellow Leaves Dropping

This is part of the normal growth cycle of the plant, usually happening in the spring. Even on evergreens, leaves only last a couple of years, so you will see old leaves dropping, but new ones will replace them.

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