Gardenias thrive in partial shade, high humidity, and an even supply of moisture and nutrients. [2] X Research source Though they can be grown indoors, the hot, dry air and gloomy winter days can send the gardenia into a downward spiral. Ideal seasons to plant gardenias are during spring or fall, when there is the perfect amount of sun without too high a heat. [3] X Research source Flower buds will fail to form if day temperatures are higher than 70 °F (21 °C), if night temperatures exceed 65 °F (18 °C), or if they fall below 60 °F (16 °C) at night. [4] X Research source Keep in mind that gardenias cannot stand to winter outdoors. You must bring them inside for the winter.
Acidity is measured on a scale from 0-14, with 0 being the most acidic and 14 being the most basic. Gardenias prefer acidic soil, so a pH level of 4. 5 to 5. 5 would be optimal since it is only moderately acidic. [5] X Research source If necessary, add sulfur — a white powder that can be bought at most garden or home improvement stores — to help lower pH levels that are higher than 6. The soil itself should also be rich and well-drained. Gardenias require plenty of nutrients but their roots may die if over-watered. [6] X Research source
A root ball is a mass formed by the roots of a plant and the soil surrounding them. If your soil is in poor condition, add a small amount of compost to the hole before laying the root ball down. Compost is organic fertilizer and will add nutrients that your soil may be deficient in. Carefully choose where to plant the shrubs. By planting close to your house, you can enjoy the scent of the blooms from a deck or through an open window. But too close may mean that the soil pH may become too high for the plants to thrive. Also keep in mind that gardenias need a lot of light, but can’t tolerate heat. Perhaps opt to plant near a bedroom window rather than a kitchen window.
Doing this will help to settle the soil and eliminate air pockets. You want your gardenia’s roots to fit snugly into the soil so that it can absorb plenty of water and nutrients. If you intend on planting multiple gardenias, be sure that you leave 3–6 feet (0. 9–1. 8 m) between each root ball. The gardenia plant can grow anywhere from 2–8 feet (0. 6–2. 4 m) both tall and wide. [7] X Research source Planting too closely can result in overcrowding or competition between roots for water and nutrients.
Monitor the soil frequently for moisture content, and water thoroughly as the top inch of the soil dries. Avoid over-watering the soil especially, because if it is kept too wet, the roots will be starved for air. [8] X Research source
Mulch not only enriches the soil, but it will also keep your soil moist, reduce the growth of weeds, and maintain constant soil temperature. For the best outcome, select a mulch made of wood chips, sawdust, or ground bark. Applying mulch is extremely important since gardenia roots are shallow, making them especially vulnerable to weeds.
Be sure that you feed with an acid fertilizer. The nutrients in this particular fertilizer are formulated for plants that prefer acidic soil. Applying regular fertilizer may not be sufficient for sustaining your gardenia. Beware of over-fertilizing, as this can lead to damaging salt accumulation.
Spraying with water raises the humidity around the plant, but only temporarily. Therefore, it must be done daily in order to ensure that the gardenia survives. [9] X Research source Other than spraying, you could plant gardenias in clusters without overcrowding them. This will create a pocket of humidity. To increase the humidity even further, you could place a dish of water in the middle of the cluster. As the water evaporates, it will cover the surrounding gardenias.
Pruning younger, dormant gardenias will cause more prolific blooming. The young plant is very resilient and will easily repair lost stems because it is not yet actively growing. [10] X Research source Remove scraggly branches and faded flowers. Gardenias are woody shrubs, so remove older, woody stems to encourage the growth of new branches. Prune the lowest branches which are in danger of touching the ground. This can lead to infections. Don’t cut all the leaves off. Some leaves need to be left so the plant can still produce food for the root system. [11] X Research source
Mealybugs are grey, segmented pests. They feed on the sap of the gardenia and leave behind a waxy coating on the plant. This can result in twig death, impair plant growth, and cause leaves to drop prematurely. Whiteflies are tiny white insects that resemble small gnats. They produce honeydew and the black sooty mold which grows on it. This mold can cause gardenia leaves to turn yellow and drop prematurely. [12] X Research source
If you are facing a large mealybug infestation, smother the gardenia with a good dose of insecticidal soap or horticulture oil. Two days after the first pass of insecticidal soap, cover the soil judiciously with a helpful fungus called Beauveria bassiana to kill any mealybugs that feed on roots. Beauveria bassiana is also available in most gardening/home improvement stores.
Secure a cardboard box large enough to cover the shrub without bending the branches. Use old blankets, straw, or bubble wrap to insulate the plant while it is under the cardboard box. [13] X Research source Despite your best efforts, the tips of the branches may die and turn black from frost or cold damage. When this happens, prune the branches a couple of inches below the damage with sharp pruning shears. Alternatively, you could transplant your gardenia to a pot and bring it inside for the winter. Though your plant will face higher chances of bug infestation, there are steps you can take to better care for your gardenia indoors.
This will be especially challenging if you brought the gardenia inside during winter, when sunlight is scarce. One option you could take would be to supplement what little sunlight the plant receives with a grow light. The gardenia will also need to be in a room with a temperature of 64 °F (18 °C) during the day and 55 °F (13 °C) at night. [14] X Research source Adjust your house’s thermostat accordingly and monitor your Gardenias’ growth. Keep your plant free of drafts and never place a gardenia where it will receive direct force of hot hair from a furnace. The drying nature of the heat could cause your gardenia to literally fall to pieces.
Also water your gardenia as needed. If you notice the top inch of the soil is dry to the touch, water until the soil is moderately moist. Check the pH of the soil frequently to ensure it stays between 5 and 6. Use plant food specifically designed for blooming plants that prefer acidic soil. A formulation for azaleas will work well.
As stated earlier, you could group your potted gardenias in a cluster around a dish of water to increase humidity. Be wary when misting your plants, however, since using direct water and a humidifier in tandem may cause fungus growth on your gardenias. You could also place your gardenias roots directly onto a tray of pebbles and water. First, place a layer of pebbles across the tray and add water until the pebbles aren’t quite covered. The pebbles will hold the plant above water so their roots don’t become waterlogged. As the water evaporates, it will increase the moisture in the air around the plant. [15] X Research source
It is best to prune after blooms have fallen. Cut away dead wood until you have reached your desired size.
Among the bugs to be on the lookout for are aphids, which are small, pear-shaped insects with long legs and antennae. [16] X Research source These bugs can be treated with a solution of one part liquid soap and one-part water. Spray both the top and bottom of the leaves. This treatment is also effective on mealybugs. [17] X Research source Spider mites are small and often hard to see with the unaided eye. To check for spider mites, shake the gardenia gently over a white piece of paper. If you notice red, yellow, brown, or green specs, you may have spider mites. [18] X Research source Treat these pests with neem oil, which is vegetable oil from the neem plant. It is available in most grocery or department stores. Neem oil will also treat the infestation of all the aforementioned bugs. If you find your gardenias have yellowing leaves despite these treatments, you may have root nematode infestation. Root nematodes are parasitic, microscopic worms that attack plants at the roots. Unfortunately, there is no treatment for this type of infestation. [19] X Research source
