Gardenia
Gardenia (Gardenia jasminoides) is a popular houseplant. It is an evergreen shrub with glossy, deep green foliage and fragrant, white blooms appearing from late spring to summer. It is native to tropical and subtropical parts of Asia and Africa and is a part of the Rubiaceae (Madder or Coffee) family. Gardenias are most popular for their beautiful and aromatic flowers, but Gardenias also make great houseplants. They prefer warm and humid conditions, and require sunny or partially sunny locations and regular watering. Gardenias have few pests, but can be susceptible to root and foliage diseases.
Gardenias have different water requirements depending on the time of year. It should be watered deeply and regularly but be sure not to over-water as this can cause root rot. During the winter season, only water the plant when the top 2-3 inches of soil is dry. During spring and summer, water the plant deeply 1-2 times per week. Reduce this amount during cooler periods and if the plant is fertilized.
Gardenias require plenty of bright, indirect sunlight to perform their best. Place in a location receiving some sun during the day, but out of direct sunlight which can scorch the fragile petals. Too much shade will cause the plant to become leggy, reduce flowering, and become more susceptible to diseases. As an indoor houseplant, place the plant near a south-facing window.
Gardenias should be grown in temperatures between 59°F-85°F (15°C-30°C) for optimal growth and performance. Temperatures below 59°F (15°C) can cause the leaves to turn brown and dry out, and temperatures above 85°F (30°C) can be too hot and can cause flower bud abscission. Keep the plants away from air conditioners and cold drafts.
Gardenias thrive in high levels of humidity. Increase the humidity levels either by misting the plant several times a day or by using a humidifier. If the temperature and humidity levels are too low, the plant may drop its flowers and buds and its leaves may start to look wilted. It is also necessary to regularly mist or wipe down the leaves to remove dust and dirt which acts as a barrier and hems in the plant's respiration capabilities.
Gardenias prefer a light soil that drains well, such as a mixture of one part organic compost (peat moss, manure, etc.) to two parts of a well-draining potting mix (perlite, vermiculite, etc). The soil should also contain a small amount of lime to help raise the pH. The pH of the soil should be kept between 5.0 and 7.0 for optimal growth.
Gardenias should be fertilized once every two to four weeks during the growing season with a balanced (10-10-10) or slightly acidic (9-6-6) fertilizer. Fertilize at half-strength and apply only when the soil is slightly moist. Do not fertilize during the late fall and winter months as the plant is resting. It is also a good idea to add a layer of slow-release fertilizer to the soil at the beginning of the growing season for sustained nutrient supply.
Gardenias are prone to several insect pests, the most common being aphids, mealybugs, whiteflies, spider mites, and scale insects. If any of these pests appear, the use of an insecticidal soap or neem oil is recommended. Make sure to spray to the point of runoff and monitor the plant regularly for further infestation. Also, remove any fallen leaves or dead foliage from the soil to reduce the risk of infection.
Repotting should be done once every two to three years in early spring. Choose a larger pot than the old one, and use a quality potting mix consisting of equal parts of peat moss, perlite, and composted bark. Make sure the soil is well-draining to avoid root rot. Newly repotted Gardenias should be watered thoroughly and then kept moist but not wet until the plant is well-established.
It's a good idea to prune Gardenias at least once or twice a year. Early summer is the prime time for pruning, at which time the plant should be shaped and dead or diseased branches should be removed. It's also a good idea to pinch off the tips of new shoots to promote a bushier plant that will be more likely to produce flowers. Gardenias can also be pruned to control their size if necessary.
Mulching is beneficial for Gardenias as it helps retain moisture, and moderating the soil temperature. Use an organic mulch such as shredded bark or straw but be careful not to pile it too thickly as this can lead to root rot. Keep the mulch away from the base of the plant and from the crown to help reduce the risk of disease.
Gardenias can be easily propagated from cuttings taken in late summer or early fall. Cut a tip cutting containing two to three sets of leaves and plant the cutting in a pot of moistened soil mix. Cover the pot with plastic to help retain moisture and place it in a warm and bright location. Keep it moist, but not soggy, and in a few weeks, the cutting should take root and produce new growth.
Gardenias don't require any support to remain upright, but may benefit from a stake or trellis placed behind the plant to help support it if it begins to droop or become top-heavy. Gardenias should also be pruned regularly to keep them from becoming leggy.
Gardenias require a period of rest and lower temperatures during the winter months. To supply the plant with this rest, reduce watering and move it to a cool, dark location for a few months, such as an unheated room or cold porch. Gardenias should not be exposed to temperatures below 40°F (4°C).
Gardenias are toxic to cats and dogs if ingested, and can cause gastrointestinal upset. If any pets are present, consider placing the Gardenia in an area where the pet cannot reach it.