How to Grow and Care for Gardenia

Gardenia (Gardenia jasminoides), a tropical broadleaf evergreen shrub, is typically grown as a large, indoor houseplant because its blooms smell magnificent. In fact, few natural scents are as evocative and memorable as the smell of this coveted plant.

If it wasn't for the plant's fragrant appeal, however, few gardeners would attempt to grow the high-maintenance gardenia, commonly found only in conservatories and commercial greenhouses. Still, if you're up for the challenge, even a few months of blooms make it a worthwhile endeavor.

Gardenia can also be planted outdoors in the spring or fall in the southern United States, or along the Pacific Coast. Gardeners typically purchase mature potted specimens for this purpose, so that they will bloom immediately. Should you choose to grow gardenia from seed, expect to wait two to three years before the plant flowers. Gardenia is toxic to pets.

How to Get Gardenia to Bloom

Gardenias have a distinctive floral, citrusy sweet scent. They look like roses with showy white or cream-colored petals that open up to a spiral around a central point. They bloom from late spring up through fall. Each bloom lasts several weeks before wilting. Deadhead or remove spent blooms after they wilt to spur more flower production.

To maximize your gardenia's blooms, ensure its growing conditions are spot on, including its recommended fertilization and watering needs.

Wait to prune your plant after the last blooms have faded. This way, you won't cut back any growth on new buds that may form.

Prevent "bud drop" (a condition known to affect this plant) by assuring humidity and water levels are just right (not too dry and not too moist).

Gardenia Care

Gardenia grows outside only in USDA Zones 8 to 11. If you live in a cooler climate, you can place your gardenia houseplant outside in the summer in temperatures of 60 F and higher. Gardenia likes to be planted in light to medium shade in a location that doesn't face competition from tree roots.

Garden gardenias prefer a planting area carefully amended with organic material to achieve rich, acidic soil that drains well. Soil should be regularly covered with a thick layer of mulch to control weeds and moisture.

A well-tended gardenia grows compact with deep green leaves and will bloom in early spring or early summer, depending on its location. This plant prefers daytime temperatures of 75 to 82 F, so keep it relatively warm when growing gardenia indoors. For this reason, outdoor potted plants must be brought indoors any night when the temperatures fall below the minimum.

Light

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.

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.

Water

Gardenia prefers about one inch of water weekly (either by rain or hand). Drip irrigation works best as it keeps water off the leaves, which can cause fungal leaf spots. Reduce watering in the winter and only keep the soil slightly moist to the touch. This winter watering method also works well for potted gardenia.

Temperature and Humidity

Gardenia requires temperatures above 60 F, free of cold drafts. This plant also prefers a high humidity level above 60%. To maintain proper humidity, indoor plants may need a humidifier or constant misting during a cold, dry winter.

Fertilizer

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.

Types of Gardenias

This plant has been widely cultivated outdoors in warm climates. Many varieties are created from plant grafting onto a Gardenia thunbergia rootstock. The grafted plants tend to grow more vigorously, with larger blooms, but they are even less cold tolerant than ungrafted species.

Here are a few recommended cultivars:

• Gardenia jasminoides 'Aimee' can grow up to 6 feet tall and bears huge 4- to 5-inch wide white flowers.
• Known as one of the best free-blooming varieties, the large shrub G. jasminoides 'Fortuniana' produces 4-inch blooms all season long.
• G. jasminoides 'Buttons' is a dwarf variety, growing 24 to 30 inches tall, and yielding 2-inch flowers.
• G. jasminoides 'Crown Jewel' grows in a 3-foot-tall compact mound and bears 3-inch flowers. This plant is known to be hardy as far north as zone 6.

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.

Propagating

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.

Here's how to propagate gardenia from cuttings:

1. Gather garden shears, rooting hormone, 3-inch pots, plastic bags, stakes, and potting soil that contains perlite.
2. 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.
3. Prepare pots with moist potting soil and poke a hole into the center of the soil.
4. Dip the cut end of the stem in rooting hormone, and then plant the stem in the hole. Backfill the hole.
5. Place plastic bags around the pots and prop them with garden stakes.
6. 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).
7. When temperatures allow, transplant the small gardenias into your garden.
   

How to Grow Gardenia 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 Gardenia

When planted in containers, gardenias prefer a high-quality, peat-based potting mix with a low pH, similar to those formulated for rhododendrons.

Gardenias are best repotted in the spring, as needed when they begin to come out of winter dormancy. Determine if your plant needs repotting by checking if it is root-bound (roots may be sticking out of the soil).

You can also re-pot if your plant looks less vibrant but has no insects or diseases. Move up a pot size and use a natural stone or terracotta pot. Both materials allow moisture to evaporate through their porous walls.

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.

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

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.