Question
I have a potted indoor hibiscus tree that bloomed successfully for several years, under the same lights (on timers) that I use for my small phalaenopsis collection.  I then had it repotted about 2-3 years ago at the same nursery where I purchased it, into a pot about 2" larger, and it has not bloomed since, even though it us under the same conditions as when it was blooming before.  All my orchids are blooming happily, so I know the light is sufficient. I would think it would be pot bound by now,so I am guessing the potting soil is the problem.  It dries out very quickly and I water weekly with weak fertilizer, Miracid, which is what I used when it was blooming before repotting.  I did try a 10-60-10 fertilizer for a while, but it didn't help and I switched back to the Miracid.  I see from your previous answer I should have stayed with the 10-60-10, so I'll return to that.

If the problem is the soil, what are the soil requirements, is there something commercially available, or a soil composition you could recommend, and should I have it repotted?  

What else might be the problem that I could try?  (I don't have a basement for cooler winter temps, so can't do the dormancy, though I did try cutting back on fertilzer with no success.) I do cut it back annually in the fall.

Answer
Hi Joyce,

The cause of the problem is much simpler than you realize and will surprise you. It was the repotting. Contrary to conventional wisdom, plants do best when they are quite potbound. This is especially true of most flowering potted plants.

When a plant is moved to a larger pot, it puts its energy into expanding its roots into the new soil, so it often stops putting out new foliage and flowers until it is potbound one again. That is what happened to yours.

Presumably, it will flowers again, but only after it is very potbound. You mentioned the artificial light, but provided no detail and didn't mention anything about natural light. It may be that you have minimal light and root growth is very slow and it may take a very long time for your Hibiscus to become potbound enough to flower. Oh, if you only hadn't repotted!

Fertilizer is vastly over-rated and mostly misunderstood. A freshly potted plant already has lots of nutrients in the fresh soil, so fertilizer is redundant. A high middle number is good for flowering plants, but a 1-6-1 ration is too extreme. 1-2-1 ratio would be more appropriate, although in your case it don't think it matters anyway. In addition, Hibiscus is not an acid-loving plant, so Miracid is not appropriate. Regular Miracle Gro would be better. But as I said previously, lets not make too much of the fertilizer because nutrient deficiency is not where the problem lies.

If you can send me more detailed information about the available light, the size of the new pot and the height of the plant, I might be able to help you further. A photo sent to my email address below would also be helpful.

If you want to pursue repotting and fertilizer further, I have written articles on both these topics that I will email to anyone who emails me a request.

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

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