Gardenias (jasminoides (Cape jasmine))are the bane of most of us who have tried to grow it as a houseplant indoors. We have problems because the Gardenia is NOT a houseplant; it is a woody shrub that prefers to grow outdoors in the tropical rain forest. In the deep South, the gardenia can be a permanent outdoor shrub. North of Atlanta, the Gardenia is a best grown as a container plant outdoors on the deck or patio during the summer and kept over the winter period indoors. So while it is indoors during the late fall to late spring, we are just trying to keep it healthy and allow it to form buds for those gorgeous blossoms when it goes back outside.
Where To Put Your Gardenia
This plant is very very picky about the conditions that surround it, both outside during the summer and inside during the winter. However, if you find the right place for it you will be successful.
Best Time To Buy
Late spring is the best time to buy a Gardenia. Make sure it has lots of buds and that all the leaves are a deep shiny green. It will probably come in a basic plastic pot, so plan on buying a continuous watering container at the same time you buy the plant. (see watering below). The Gardenia blooms best when it is potbound, so don’t transplant it into a new container much bigger than the one coming from the store. If you buy a young plant, you can repot it every year as it grows, but then after three years or so, no more repotting.
Gardenias kept indoors must have high humidity and cool nights as well as plenty of sunlight. The plant will not set buds if night temperatures exceed 65F
The plant can be placed outside in a large container as long as it is screened against the brightest sunlight. Feed every two weeks. At night, the temperature should not fall below 61 F which could be problematic in cold summers. If this does happen, chlorosis will set in shortly after, indicated by yellow leaves. In the winter, the Gardenia has to be brought inside a moderate greenhouse with lower temperatures. In any case, it should not grow. When the buds have formed, the temperature at night should not rise above 63 F otherwise they will fall off.
Seasonal care - plant rests following blooming, lasting from early winter to early spring. Gradually reduce water, letting soil surface dry between waterings, withhold fertilizer.
Much light, no full sun in summer. Keep in about 4 houyrs of direct sun in winter. In summer provide curtain-filtered sunlight from a south or west window.
The reality is that they are happiest with 50F to 55F at night and 65 to 70 during the day. In the winter place them in an unheated guest room with good light, preferably east or southeast facing.
Gardenias need long, cool nights (under 65F to set flower buds. Buds often (drop)if the humidity is low, soil is too wet, or light is too low.
Grow moderately warm, in the winter not below 54F and the soil temp preferably even higher.
Keep moderately moist, but do not let sit in water; best to use wick watering or continuous watering pots.
Feed every two weeks with Miracid at half strength, from early spring thru ealrly fall; then (drop)off to zero in early winter to early spring.
Use an acid balanced fertililzer and add trace elements once in the spring
Prune in early spring. Pinch back stem tips of young or regrowing plants to improve form. Do not destroy flower buds. Remove faded brown flowers. Prune severely after flowering at end of summer.
Gardenias thrive when given a half inch to one inch layer of used coffee grounds, assuming you water from the top. If you use continuous watering pots then mix coffee grounds with the potting soil.
You are looking for a pH of 5.0 so even watering occassionally with dilute cold coffee, can help.
Moderate 50-60%; best to use humidity tray at all times.
Gardenias want an acidic condition so the ideal potting mix is equal parts of peat moss, perlite and pine bark; I add a cup of used coffee grounds for acid’s sake.
Bud (drop)results from plant stress. It does not tolerate drafts or changes in temperature. If soil is too wet or too dry, leaves will drop. This plant will not bloom if light is too low.
Avoid moving a gardenia once it is established in a spot. It is important to situate it in same angle to the light if it is moved. ]
Can be hit with aphids, mealybugs, scale, whiteflies. Low humidity causes black leaf tips; cold water results in yellow leaves.