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How to Grow: Gardenia
Full sun in cooler climates where gardenias grow, but afternoon shade in warmer locations. A North or East facing location is best in warm areas.
Bloom Period and Seasonal Color
Blooms in summer
Mature Height x Spread
4 to 8 feet tall and wide
Gardenias are prized, dark green, glossy evergreen shrubs that are perennials in USDA zone 8 and warmer climates. There are some selections that survive zone 7 with protection. The real treat are the white, highly fragrant flowers that form in summer. Gardenias make nice landscape shrubs where they grow as perennials. Varieties range in size from 4 to 8 feet, so select a good location in your yard where the mature plant won’t over grow the space.
Gardenias are heat lovers, but in very hot summer climates, they benefit from some afternoon shade. They area bit fussy about soil and moisture. They thrive in an acidic soil that’s kept consistently moist.
When, Where and How to Plant
Plant gardenias in spring or fall in a location with well-drained, acidic soil and full to part sun. They make great foundation plantings or can be grown in a mixed shrub or perennial flower border. Smaller varieties can be grown in containers.
Dig a hole three times as wide as the root ball and as deep. Remove the potting soil from the root ball and examine the roots. Prune off any circling roots and space them evenly around the shrub. Plant adding water and soil to back fill the hole. Don’t add compost or fertilizer to the hole.
Gardenias grow best with a pH between 5 and 6 – similar to rhododendrons. Ideally, amend the soil with sulfur 6 months before planting to alter the pH of the soil if needed. Apply sulfur annually to keep the ph low and use a fertilizer in spring meant for gardenias. High pH will cause the plant to grow poorly and cause yellowing of the leaves.
Gardenias also like a well-drained, organic soil. Apply compost annually to add water retention to sandy soils and drainage to clay soils. Keep the soil evenly moist with irrigation and mulch.
Gardeners in cold climates may try to grow gardenias indoors. It’s rare that gardenias will grow well indoors and set flowers due to the low humidity and light conditions. They perform best in a greenhouse, under grow lights or in a sunroom. If they do survive the winter indoors, move the containers to a sunny deck or patio in early summer to help the plant thrive and you may get flowers by the end of summer.
Gardenias don’t require much care once you have found the right soil and pH for them. Prune in late summer after flowering to remove dead, diseased and broken branches and to shape the shrub. It’s not essential to prune annually. Prune when the shrub starts growing too big for the space of if you need to open up the shrub’s structure for better growth.
Gardenias can have a variety of problems. Sooty mold is a disease that causes the leaves to turn gray colored. It’s often caused by white flies or other insects feeding on the leaves. To get rid of sooty mold, get rid of the insects with insecticidal soap sprays. Flower buds will sometimes drop due to uneven watering or lack of light. Mulch and make sure your gardenia gets enough sun. Flowers not forming may also be due to lack of light or too heavy pruning the previous year.
Companion Planting and Design
Gardenias grow well with other shrubs around to compliment their dark, green, glossy foliage and white flowers. Rhododendron, camellia, boxwood, and clethra are all good companions. They will in similar sun and soil conditions as gardenias. Perennials, such as hosta, ferns, and primose, make nice complimentary flowers in front of gardenia shrubs.
‘Crown Jewel’ is a dwarf gardenia that grows 3 feet tall and wide. It’s more cold tolerant that other varieties and blooms twice a year. ‘Golden Magic’ is an unusual gardenia for its yellow, fragrant flowers. ‘Buttons’ is a good heat tolerant variety. ‘Chuck Hayes’ is a medium-sized shrub that blooms from early to late summer. ‘Mystery’ is large selection with 4 inch wide fragrant, white flowers.