The gardenia is a tender evergreen shrub with amazingly fragrant flowers and shiny, dark-green leaves. It’s native to the tropics and needs a bit of extra care to grow its best. Here's how to plant, grow, and care for gardenias in your garden!
About Gardenias
The main species of gardenia (also known as "cape jasmine") grown in North American gardens is a native of the tropical regions of East Asia, including southern China and Taiwan. In this part of the world, the plant has been used for centuries in herbal medicine. Its yellow fruit was traditionally used to make a dye, which could then be used to color food and clothing.
Gardenias are known to be a bit of a challenge for gardeners. Frankly, the plant is picky and often needs more attention than other flowering shrubs. It prefers fairly acidic soil (a pH of 5.0 to 6.0), likes a tropical climate (but suffers in too much direct sun), and doesn't transplant well. Nevertheless, with a little extra work, a gardenia can be a wonderful addition to a suitable garden.
If you happen to live within a hardiness zone colder than Zone 7, you're not out of luck when it comes to gardenias! They can also be grown indoors in pots. Put them outside during the warm days of summer and take them indoors for the cooler seasons.
There are many varieties of gardenias to choose from, depending on what you're looking for. There are compact plants that only grow 3 to 4 feet tall and there are giants that grow up to 8 feet in diameter. Some bloom early in the summer and some bloom later. Some varieties have only a few huge blossoms and others have many small blooms. There's something for everyone!
Planting
When to Plant Gardenias
- Generally, the best time to plant gardenias is in the fall. In areas that get a light frost, plant gardenias at least 6 weeks prior to your local fall frost date.
- In cooler regions (Zones 7), it's best to plant in the spring, as this will ensure that the gardenia has plenty of time to settle in before winter.
Choosing and Preparing a Planting Site
- Consider the strong fragrance of the gardenia's flowers when choosing a planting site. While their scent is enjoyable in passing, it may become overbearing if the shrub is planted near a window or frequently traveled area!
- Gardenias appreciate a tropical climate, but may suffer in full sun at the height of summer.
- In warm regions (Zones 8+), select a spot that gets morning sun and light afternoon shade, but that avoids the harsh midday sun.
- In cooler areas, select a spot that gets full to partial sun.
- Choose a sheltered spot where the gardenia will protected from cold winds in the winter.
- Gardenias require a low soil pH (acidic) of between 5.0 and 6.0 to grow well.
- Soil should be rich and moist, but well-draining. To increase the fertility of the soil, add aged manure or compost to the site before planting.
How to Plant Gardenias
Gardenias do not transplant well and respond poorly to root damage. Because of this, handle the plant with care during planting!
- Dig a hole that is twice as wide and a bit deeper than the root ball.
- Put a couple of inches of fresh soil in the bottom of the hole.
- Place the gardenia in the hole so that the top of the root ball is even with the soil surface.
- Fill in with soil around the root ball.
- Water deeply.
- Add 2 to 4 inches of pine straw or compost around the plant, leaving bare soil right around the stem to allow for air flow.
Care
How to Care for Gardenias
- Gardenias grow and bloom best when temperatures during the day are between 65 and 70ᵒF (18 to 21°C) and night temperatures are between 60 and 65ᵒF (15 to 18°C).
- Keep watering consistent. Gardenias will suffer if they dry out or are overwatered.
- Gardenias enjoy high humidity. Mist with water during dry spells.
- Fertilize with a slow-release fertilizer formulated for acid-loving plants such as rhododendrons and azaleas a couple of times during spring and summer. Do not fertilize in the fall, as this can cause a spurt of frost-tender growth.
- Routinely remove faded flowers to encourage more blooms.
- Bud drop can be caused by low humidity, over- or under-watering, insufficient light, and high temperatures.
How to Prune Gardenias
- Prune younger plants only to keep the plant nicely shaped.
- Prune back the new growth of established plants by two thirds after flowering.
How to Propagate Gardenias
- In early spring, take a 4 inch stem cutting just below a leaf.
- Dip the end of the cutting in rooting hormone.
- Put the cutting into a pot with a mix of perlite and potting soil.
- Keep the soil moist.
- Transplant the cutting into a bigger pot after it has rooted.
How to Grow Gardenias Indoors
- Gardenias grown indoors need 6 to 8 hours of bright, indirect sunlight through a window.
- The gardenia is very sensitive to temperature changes, so keep it away from air conditioning, heat vents, and drafty windows.
- The plant prefers 70ᵒF (21°C) during the day and 60 to 65ᵒF (15 to 18°C) at night.
- The gardenia likes high humidity. To increase humidity, place the potted gardenia on a shallow tray with gravel and water. Water will evaporate and increase the relative humidity around the plant. Alternatively, place a humidifier close to the plant or mist the leaves often with water.
Pests/Diseases
Insect Pests
- Aphids
- Mealy bugs
- Scale insects
- Spider mites
- White flies
Diseases
- Powdery mildew
- Root rot
- Stem canker
- Nematodes
Recommended Varieties
Smaller Gardenias with Repeat Blooming
- ‘Chuck Hayes’ is a cold hardy cultivar that grows to 4 feet high. It has semi-double, 2 to 3-inch flowers during summer and re-blooms in the fall.
- ‘Kleim’s Hardy’ is hardy to 10°F and grows 3 feet tall and wide. The single flowers bloom in early summer and have a second bloom in the fall.
- ‘Variegata’ has interesting variegated foliage and beautiful double flowers on a small, 3 to 4 foot tall and wide plant.
Larger Gardenias with Double-flowers
- ‘August Beauty’ grows 4 to 6 feet high and 3 to 4 feet wide. It blooms from mid-spring to fall with double 3-inch flowers.
- ‘Mystery’ has large 4- to 5-inch double white flowers that fade to cream yellow. It grows 5 to 6 feet tall and about 3 to 4 feet wide, but may get larger.
- ‘Veitchii’ is one of the oldest cultivars and grows to 4 to 6 feet tall and 3 to 4 feet wide. It has double flowers with a long bloom period.
Harvest/Storage
Gardenias as Cut Flowers in a Vase
- Don’t touch the blossoms with your bare hands, as they may bruise and wilt.
- To help absorb water cut the woody stems at a 45 degree angle.
- Remove the bottom leaves so that no leaves will be below the water in the vase.
- Add a tablespoon of sugar and a teaspoon of bleach to the water in a medium vase.
- Place gardenia blossoms in a bowl or a cup of water as floating blooms.
Wit and Wisdom
- In the language of flowers gardenia symbolizes "secret love."
- Gardenias were named after the Scottish-born American naturalist Alexander Garden (1730–1791).
