long beach, CA
|Why Gardenia's leaves turning black at the tips. Some of them still not fully open yet.
|Answer from NGA
May 17, 2010
|Temperatures below 50F can turn the leaves black. You can prune away the damaged plant parts and the new growth will be healthy. About the only other thing that can cause off color foliage is feeding by aphids or other sucking insects. When they feed they exude a sticky substance called honeydew which will turn black as it ages. You normally see this sooty mold condition on leaves lower than where the feeding took place. Since the tips of the leaves of your gardenia are turning black, I suspect it is weather related rather than caused by insect pests.
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