11-13-2012 05:53 PM - edited 11-13-2012 06:00 PM
Thank you for your question and welcome to our community. I would have loved to of seen a picture of your gardenia. There are a couple of things that could be attacking the leaves of your plant. If the leaves have holes in them your Gardenia could have grass hoppers eating the leaves. There are also a variety of caterpillars that also love to feast on the leaves as well. Thripes will also poke holes into the leaves your gardenia. Aphids love gardenias and will usually populate the underside of the leaves, sucking the fluids out of the plant.
This feasting by the insects should not cause the leaves to fall off however. When the leaves are falling off, it could also be an indication of water-too much or too little, soil, too much sunshine or a lack of, or even too cold of temperature. Outside gardenias do best in zones 8-10. Out here on the West Coast, many of the Gardenias are morning sun plants due to our lower humidity.
Gardenias will do best in a well-drained, acidic soil with a pH of 4.5 to5.5 whether in the ground or in a pot. If the soil is too damp or even too dry, you can experience leaf and bud drop. Peat moss is a great additive for your gardenia. This will help you plant out by retaining moisture and adding some acidity to your soil.
The ideal temperature for the gardenia will be from 68 to 74 degrees F during the day with a low of 60 degrees F at night. This plant enjoys a moderately humid environment. Be careful about misting your plant with the hose as this can lead to a fungal growth on your plant.
A treatment for your plant with bugs on it can be two fold. I like to use the Bayer or Ortho product which is watered into the ground around the plant or the granular product sprinkled onto the ground at the drip line of the plant.
As this drench or granular percolates down into the ground, the treatment is pulled into the system of the plant thru the feeder roots. This treats the plant from the inside out, making the leaves taste bad to the bugs trying to eat or suck the fluids out of the plant.
You can also spray your gardenia with a topical or a systemic spray. I prefer using the systemic spray when treating ornamental plants. The systemic spray is observed by the plant rather than just sitting on the surface where it can be washed off by rain or from the sprinklers.
There is also a selection of organic insect control that is also available as well.
If you can take some pictures of your gardenia and share its progress with us that would be great. Please let us know if we can be of further assistance to you.
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