Gardenias are known—and grown—for their intoxicating sweet fragrance produced by waxy white blossoms. These beautiful evergreen plants boast shiny, emerald green foliage. However, if gardenias are planted in soil that is too alkaline, they are likely to yellow. While people commonly try to grow gardenias as houseplants, they can be finicky as they require high humidity. Even if they are short for this world, they are worth it just to get one good whiff of their intoxicating flowers.
When grown in the ground where gardenias are hardy, their foliage creates a wonderful backdrop for other plants. Gardenia flowers are thickly petaled and are found in a variety of shapes and sizes. Most common varieties are double forms like roses, but you can also find single varieties with a row of petals often in a star pattern. No matter the shape or amount of petals, gardenias always exude their signature scent. A unique trait of gardenia blossoms is that they typically bloom as a bright, clean white and fade to a creamy yellow as they age.
Gardenia Care Must-Knows
One of the most common reasons gardenias fail in a garden is because they need acidic soil. When grown as a potted plant, you will need to use acidic-based fertilizers and also keep in mind that water affects the soil's acidity. Gardenias prefer well-drained, organically rich soil. Be sure to give your gardenia plants plenty of water; they may require up to 1 inch per week. Humidity is another important factor when growing gardenias. These plants are native to tropical areas with very high humidity, so having the proper humidity levels in a home setting is essential.
If you are planning to grow gardenias indoors, they need as much sunlight as possible. This encourages a good bloom set as well as deep green foliage. In an outdoor setting, gardenias prefer a little protection; their ideal setting is indirect sunlight, especially during the winter as their evergreen foliage can burn in full sun.
Pests and Diseases
Gardenias can be susceptible to a wide variety of pests and diseases. Two common pests are mealy bugs and scale, which are often found feeding on the stems and undersides of the leaves and are fairly immobile. Mealy bugs are identified by their cottony white egg sacks, while scale is a hard, brown-shelled pest that does not move. White flies, which have small green bodies with white wings, are also found on the undersides of leaves. Sooty mold on the foliage is an indicator of an infestation of the flies and the sticky honeydew they secrete.
All of these pests are fairly easy to control with insecticidal soaps, though scale can be tricky because of their hard outer shells. To control these common pests, use a systemic insecticide.
Another problem for gardenias is bud drop, which is usually caused by issues with humidity, overwatering, or insufficient light.
More Varieties of Gardenia
Gardenia augusta 'Veitchii' bears white double flowers over a longer season on a 6-foot-tall shrub. Zones 8-10
Gardenia augusta 'Mystery' bears pure-white semidouble flowers on a compact shrub that grows to 3 feet tall and 5 feet wide. Zones 8-10