Question
I have 2 janet craig compact plants that i have just purchased on clearance d/t the heat. The leaves were black at the tips. I trimmed them back and repotted them. The leaves are begininning to turn black at the tips again. What causes this and what can i do?

Answer
Hi Chelle,

Black tips on a Janet Craig compacta can be caused by excessive heat or cold or root damage due to excessive soil moisture.

In excessive heat, it is the leaves that are damaged first because the roots are partially insulated by the pot and soil. Trimming off the damaged tips usually resolves the problem.

However, if the heat exposure was for an extended period of time - several days or more - then the roots may also be damaged by the heat. With root damage, the damage to the leaf tips will continue even after you trim off the initial tip damage. How long it continues depends on the degree of root damage.

It is never a good idea to repot a new plant, but it is a particularly bad idea with a plant that is ailing. The added soil from repotting will act as a sponge and retain water for too long. Damaged roots use less water and are more susceptible to root rot.

I suggest that you undo your repotting by removing all the soil you added and moving the plant back into its original pot. Keep the soil drier than usual and keep the plant inside in bright indirect light and away from temps above 85 degrees. Also, avoid fertilizer as it is intended only for healthy plants.

Your plant is under stress so it is hard to say if or how long it will take for it to revcpver. Be patient and watch for slow signs of healthy new growth.

I have written an article on repotting that I will email for free to you (or anyone else) who sends a request to me at [email protected].

Please let me know if any of this is unclear or if you have any additional questions.

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Regards,
Will Creed, Interior Landscaper
Horticultural Help, NYC

Visit my website at: A link to HorticulturalHelp.com