Gardenias often look their best at this time of year. Their new green foliage provides the perfect backdrop for their bright flowers. And the aroma can be heavenly. No wonder people love gardenias when they are in bloom.
However, we also want our plants to look good the other 50 weeks of the year, not just when they are in bloom. Enjoy the looks and smell of your gardenia, but make plans now to keep them looking their best throughout the year.
Gardenias have a large bloom at the beginning of the year that is followed by sporadic blooming through the summer. The amount of summer blooming you get is related to the variety of gardenia you have. Flowers are creamy yellow to white and have a unique aroma.
In my opinion, gardenias can be temperamental. In many locations they grow well with little care, but in others they struggle. Gardenias prefer a well-drained but moist soil. Morning sun and afternoon shade is probably best, but they can withstand conditions from full sun to light shade. When planting, select an open area where the aroma of the flowers can travel. Planting close to walk ways is good, but give them plenty of room to grow since some types can get 6 feet tall and wide.
Plant into a well-tilled bed to which you have added organic matter. Plant them no deeper than they originally grew and then mulch the plants with 2 to 3 inches of mulch. Pull the mulch several inches back from the base of the plant. Water management is very important for good flowering.
If soil moisture fluctuates when the plant is in bud, the flowers can fall off. For established plants, water deeply once a week to keep the soil moist but not overly wet.
If gardenias do not seem to grow well in a location, the soil may be too wet or too dry or have nematodes present. You may just want to plant another plant in these locations and find spots better suited to gardenias. When gardenias find a spot they like, they can be very hardy and attractive. If they do not like the location, they may never thrive.
If necessary, prune gardenias after the first flush of blooms are gone. Prune by removing individual long branches until the plant is the shape and size that you want. Do not prune after Sept. 1, since the plant will begin forming flower buds for the next year. Fertilize lightly in May and again in late June and August if you want the plant to get larger.
Gardenias have one major pest -- whiteflies. These small white flies attach to the undersides of the leaves and suck plant juices. The immature whiteflies will look like clear scales on the underside of the leaves. They are very hard to kill with traditional insecticides.
Imidacloprid is a very good insecticide for whiteflies. It can be used as a spray or poured around the roots as a drench. I recommend that you drench the plant with imidacloprid early in the season. It will take several weeks or more to be effective. In the meantime you may want to spray the plant with a traditional insecticide to protect the it until the imidacloprid begins to work. The best time to apply the imidacloprid is just before the leaves begin growing in the spring, but you can apply it now as well. Read and follow all label directions when using any pesticide.
When whiteflies, aphids and mealybugs feed on plant sap, they exude a sticky sweet honeydew on the plant. A black sooty mold grows on the honeydew turning the leaves black. The sooty mold can actually be scraped off with your finger. Although sooty mold is a fungus, the main problem is the insect causing the fungus. Kill the insect and the sooty mold should disappear.
Bud drop can be a problem with gardenia. Root injury, insect damage, or wet and dry soils cause buds to fall before they bloom.
Once again, good care can prevent this problem and help to give you a plant that looks good all through the year.
Willie Chance retired as the University of Georgia Extension agent for Houston County. Contact him at 929-1997.