Gardenias and tips for eliminating pesky bugs

When I moved from California, I brought with me a beautiful, big, 3-year-old potted gardenia plant. At first, the weather seemed a little too dry for it, or perhaps the move bothered it, but the leaves became very limp. I watered the plant on a regular basis and fed it a little, and its health was restored, firm leaves with blossoms.

Now the plant has acquired very tiny black bugs. They especially like to stay on the new leaves and something is eating the leaves. Is there something I should be doing to eliminate the bugs besides picking them off?

— Lily

As I’m sure you already know, gardenias are fussy, demanding, temperamental plants. I like to think of them as the little spoiled rich kids of the plant kingdom.

They like fairly constant moisture in the soil, but not too much. They want great drainage in the soil, but don’t let them dry out. They want high humidity, acid soil, good light but not too intense, warm temperatures but then not too hot, constant feeding and on and on.

In Southern California where I grew up, the conditions were fairly good for them, and I remember they still gave people fits. However, in their defense they really are pretty plants with leathery, dark green glossy leaves. But it’s their flowers that really attract people. Pure white, 2- to 4-inch diameter flowers that are exceedingly wonderfully, marvelously, stupendously fragrant.

As you’ve probably figured out, conditions here really aren’t all that good for them. That’s why I don’t sell many of them. They are just too much of a hassle to put up with. I don’t intend to discourage you, but I want you to know you have a challenge before you.

Gardenias need to come inside for the winter. We’re too cold here for them to survive year-round outside. You can keep them outdoors during the spring and summer and into the fall; just put them in a shady area that still gets pretty bright light. Indoors, you want to give them very bright but indirect light.

Water them frequently. The soil should stay somewhat moist but not soggy. Allow the water to drain through the pot into an oversized saucer beneath the pot so you don’t build up salts in the potting soil.

Don’t let drainage water stand in the saucer. Use a turkey baster to suck up the water.

Feed them regularly with an acid forming fertilizer. There are plenty of commercial plant foods or homemade recipes you can use.

Providing enough humidity to make the plant really happy is the hardest thing to do. I like to use what are called humidity trays to do it. These are simply large oversized plastic saucers that are filled with gravel. You fill the saucer with water to where it comes up just below the top of the gravel and then you put the plant on top of it. Just make sure the bottom of the pot sits above the water and not in it. As the water evaporates, it helps raise the humidity around the plant. It’s also helpful to surround gardenias with other plants, which will help to raise the humidity.

Anyway, as to your question about the little black bugs. I’m not really sure what you may have. I know that the two most common insects that affect gardenias are white fly and aphids.

From your description, you don’t have white fly, but it could be aphids. The problem is that aphids don’t eat the foliage, they suck sap from the plant.

So it sounds like you have something else going on. The best thing to do would be to clip off a sprig or two from the plant that show the black bugs and the feeding damage, put them in a Ziploc bag and bring them to the nursery for us to look at. Once we identify what is troubling you, we can then recommend the best way to control it.

Dennis Hill is the nursery manager at Bookcliff Gardens, Send questions to Bookcliff Gardens, 755 26 Road, Grand Junction 81506; or email .(JavaScript must be enabled to view this email address).


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