B. Rosie Lerner
Extension Consumer Horticulturist
Gardenia: A Gardener's Challenge
Gardenias have a well-earned reputation for being difficult specimens
for even the experienced indoor gardener. Gardenias thrive on bright light,
high humidity, and an even supply of moisture and nutrients. When gardenias
are freshly delivered from a greenhouse grower, their glossy leaves and
heavenly-scented blooms just about cause the plant to leap into your arms,
whether a gift for yourself or for a loved-one.
But, then, the plant enters the home environment where hot, dry air and
gloomy winter days send the gardenia in a downward spiral. Those delicate
flower buds, so filled with promise of good things to come, begin dropping
from the plant in droves. The glossy leaves turn dull, yellow, and they,
too, begin to drop like tree leaves in autumn. If the plant survives this
cruel change in environment, mealy bugs, spider mites, scale insects and
stem cankers provide further challenges to overcome.
Now for the good news. Gardenias can be successfully grown in the home,
but they won’t tolerate neglect like many other houseplants. Gardenias
are native to China and Japan but also grow well as an evergreen shrub
in the south and west coastal areas of the United States. There, the plant
reaches up to 6 feet tall! Gardenias thrive in bright light, cool temperatures
and moderately humid air.
Your challenge in growing the gardenia as a houseplant is to match the
plant’s native environment as closely as possible. First, make sure
you give the plant plenty of bright light, preferably direct sunshine
for at least half a day. Winter will likely be the most difficult time
to keep high light intensity due to shorter, gloomy days. Moving plants
closer to southern-exposure windows and/or supplementing with plant-grow
lights will help. Cooler room temperatures are best for the gardenia,
around 55 F at night and about 10 degrees warmer by day.
Maintaining proper relative humidity is a challenge, particularly during
the winter heating season. There are several ways to help increase humidity,
including running a humidifier and grouping plants together on trays of
wet pebbles. Misting by hand with a spray bottle offers only momentary
relief and so does not really increase humidity in a meaningful way.
A healthy, blooming gardenia will need to be nurtured with a steady supply
of water and nutrients, but don’t overdo. The goal is to provide
the proper balance of water, air and nutrients. If soil is kept constantly
wet, the roots will be starved for air. Too much fertilizer can lead to
damaging salt accumulation. Monitor the soil frequently for moisture content,
and water thoroughly as the top inch of soil dries. Use a fertilizer that
is formulated for acid-loving, blooming plants, such as an azalea-type
product, according to rates listed on the label.
Don’t be afraid to prune the gardenia; in fact, blooming will be
more prolific on younger growth. Remember that the gardenia is a woody
shrub in its native environment and so may need to have older, woody stems
removed to encourage new branches.
Though the responsibilities of gardenia care are daunting, if you persevere,
you’ll be rewarded with elegant white blossoms and sweet fragrance
that simply cannot be matched by other plants.