#TeachingTuesday: Gardenia

#TeachingTuesday: Gardenia

By Myatt Landscaping, Posted in
August 18, 2020

#TeachingTuesday: Gardenia

This week, we’re focusing on gardenia, also known as cape jasmine. The scientific name is Gardenia jasminoides. The genus name honors Alexander Garden (1730-1791), a Scottish physician, botanist and zoologist who settled in Charleston, South Carolina in 1752. Gardenias are a nostalgic summer plant for many southeastern states. Zone 7b is the farthest north it can be grown without winter protection, but in many northern states it is grown as a container plant and brought indoors for the winter. There is really no competitor that can match the dark green glossy leaves, and large, white, extremely fragrant flowers. To take full advantage, these shrubs are often grown as a hedge around porches or decks where the scent can be enjoyed in the evenings.


When grown within their hardiness rage, gardenias are tolerant of full-sun to part-shade. They do best in well-drained acidic soils rich in organic matter with regular moisture, but are tolerant of drought once established. Alkaline soils may cause yellowing (chlorosis) of the leaves. This can be corrected over time by applying compost, leaf mulch, and fertilizers for acid-loving plants. Make to plant gardenias in an area protected from strong winter winds, which may cause winter burn. Gardenias are deer-resistant, making them a great choice for those who live in areas with a lot of wildlife.

'Frostproof' is a common cultivar that is small and dense, with narrow leaves.


Gardenias do not like having their roots disturbed. Avoid breaking up the soil beneath the shrubs as much as possible, and use mulch to limit the need for pulling weeds. Gardenias are also heavy feeders, so be sure to add plenty of compost and organic material or fertilizers in the spring. It is optional to apply fertilizer again in the summer to encourage continued blooming (avoid high-nitrogen content fertilizers during this time). Do not fertilize in the fall, as this will stimulate new growth that will be frost-tender going into the late fall and winter.

Pruning should be done after flowering is finished. Remove straggly branches to improve the overall shape and thin branches as needed to improve air circulation. Good air flow throughout the shrubs will reduce the pest and disease issues that are common with gardenias, such as powdery mildew, leaf spots, dieback, anthracnose, sooty mold, whiteflies, mealybugs, scales, aphids and spider mites. Ensuring the shrubs are healthy and not under water or nutrient stress will also mitigate issues. Using drip irrigation instead of spray heads can help reduce leaf spot.

Sometimes, you may notice flower buds or leaf buds turn black at the tips. This is usually due to sudden temperature changes such as a cold snap, and will not affect the health of the shrub. Gardenias are very sensitive to cold temperatures. During a polar vortex or other extreme cold weather, you can protect gardenias by piling straw around the shrubs and wrapping in burlap if they are not too large.

ID Tips

  • The leaves are opposite or whorled (three leaves joined at the same point on the branch).
  • The leaves are evergreen, leathery, lustrous or glossy, dark emerald green, and grow 2-4 inches long.
  • The flowers are 2-3 inches in diameter, waxy, and white, aging to yellow.
  • The flowers are noted for being extremely fragrant.
  • There are both single- and double-flowered forms (two or more rows of petals).

Compare the foliage of 'August Beauty' (left) to 'Frostproof' (right).