The Gardenia, a popular flowering houseplant, is considered challenging by many indoor gardeners. This plant is, in fact quite simple to grow under the proper conditions. Lustrous foliage and fragrant blossoms will be your reward if you can provide the essentials for success outlined here.
Gardenias grow best when exposed to a minimum of five hours of full sunlight each day. They are happiest when placed in a south or east facing window. In mid-May, move the plant outdoors to a covered patio or shady spot in the garden. If it’s not possible to place your gardenia outdoors, protect it from the strong summer sun indoors by moving the plant a few feet from the window, or soften direct sun by drawing sheer curtains, partially closing blinds, etc. In fall, bring the plant indoors before the first frost.
Avoid placing your gardenia near an air conditioning unit, heating outlet or radiator. Do not place the plant near a drafty window or where there will be sudden fluctuations in temperature. A relatively cool growing area should be selected since high temperatures may result in leaf and flower bud drop. Day temperatures of 65ºF to 70ºF and night temperatures below 65ºF are ideal.
There are several measures you can take to increase humidity. 1) Set the pot on a layer of pebbles in a waterproof tray. Pour water into the tray, keeping the water level just below the top surface of the pebbles. (The pot should remain high and dry on top of the pebbles.) The evaporation of water from the tray will moisten the air. 2) Group your gardenia with other plants which require the same growing conditions. Evaporation of water from the soil surfaces and transpiration from the leaves helps to increase humidity in the immediate area. 3) Mist gardenias daily with tepid water.
Gardenias grow best in acid soil. Choose a fertilizer that is recommended for use on acid-loving plants. Feed gardenias every two weeks at half the strength recommended on the label. Cease fertilizing during the short days of winter when the plant is not actively growing.
Water your gardenia with tepid water when the top layer of soil begins to feel dry to the touch. Soak thoroughly, until water runs out the drainage holes in the bottom of the container and into the saucer. Be sure to discard the excess water which accumulates in the saucer. Gardenias prefer soil that is uniformly moist, not soggy.
The following mixture is recommended for gardenias: Two parts peat moss, one part perlite or sharp sand, and two parts packaged potting soil. When repotting, place a layer of pebbles or clay shards in the bottom of a clean pot which is 1 inch (in diameter) larger than the old container. Add enough fresh soil so that when the plant is placed in the pot the soil surface is one or two inches from the rim of the pot. Fill in around the old soil ball with the mixture described and soak thoroughly.
Your gardenia may be propagated from stem cuttings. Take a 3 to 4-inch cutting from the tip of a non-flowering shoot. The cutting should be firm and somewhat woody. The cut should be made just above a node, the point where a leaf is attached to a stem. Insert the cutting into moist vermiculite. Roots will form in 4 to 6 weeks. Newly rooted cuttings can be planted in 3-inch containers filled with the soil mix recommended above.
The following insects may trouble your gardenia:
Mealybugs: Symptoms include stunted growth and white, wooly spots along stems and leafundersides. Remove insects with a cotton swab dipped in alcohol or apply ultra-fine horticultural oil.
Scale insects: Brown raised spots along stems and stunted growth could indicate scale. Remove them with a soapy cloth or blunt knife, or apply ultra-fine oil.
Spider Mites: These pests suck the juices from the leaves, leaving a network of tiny yellow spots on the surface. You may be able to see their fine, small webs on the undersides of the leaves or between the stems. To control spider mites, spray the plant forcefully with water or apply ultra-fine horticultural oil.
Some other problems:
Fungus Disease: Yellow or brown leaf spots, about ¼ inch in diameter, may indicate foliar fungus disease. Treat the plant by picking off and destroying infected leaves, then increase air circulation around the plant and avoid overwatering.
Leaf and Flower Bud Drop: Buds may drop if the temperature is too high, if humidity is too low, or if there is insufficient light. If necessary, adjust these conditions as described above.