Question
All of my Hibiscus are outside. All get frosted back every year. I already use BloomBuster. This is the 3rd or 4th year that the 2 have not bloomed while the others do.
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Followup To

Question -
Gainesville, FL zone 8/9. I have 2 hibiscus plants that get frosted back every winter but grow back like crazy and get over 4 feet tall. But, they never bloom; never even get buds. I used "bloom buster" every 2 weeks for the last few summers - but still nothing. They are in the middle of my yard & get plenty of sun. My other hibiscus by the house bloom and they don't get as much sun as the others. No bugs, but no flowers - why? Any suggestions?

Answer -
Miracle Gro "Bloom Buster" is a 10-52-10 high-ammonium phosphate fertilizer that would encourage blooming.  This is a great fertilizer to generate buds and large flowers at the beginning of the season.

But NO fertilizer will be able to repair severe injury from a frost-damaged Hibiscus.  It sounds like they are coming back beautifully.  For a full recovery, they need Hibiscus-friendly temperatures.

That means minimal exposure to freezing temperatures.

As you can see, your indoor specimens, with a lot less sun, are doing cartwheels next to the imperturbable but non-flowering plants you are leaving out in the elements every winter.  There's a reason they're called "Tropical" Hibiscus.


Answer
OK, Barbara - I think I misunderstood your question.  Re-reading it now, I see you said, "My other hibiscus BY the house bloom."  I think I thought you said "My other hibiscus IN the house ..."  Different story altogether.  I apologize for that.

I can only guess about this problem.  Remember, I am in Zone 7, Long Island, not in Florida.  We do grow Hibiscus outside, and it's hardy - you can freeze it 'til the cows come home and it will come back almost every year.

But you are in Florida, growing tropical, tender Hibiscus, Barbara.  And I grow that too.  But I grow it indoors.

I will venture a guess here about your Hibiscus problem.  And that would be that the less sunny location of the Happy Hibiscus, which are blooming on schedule to everyone's delight, is better protected because it is next to the house.

Less cold wind.  Less fluctuation in temperature.  But really, do you have cold wind and temperature changes in Florida?  If you can swim in the weather, I think any Hibiscus would be happy there too.

The non-blooming but sun-drenched Hibiscus is suffering from damage that is destroying the buds or bud producing growth.  Since you have been incredibly patient with your Hibiscus, and with me, I think you have given them enough time to settle and show you what they can do there.  You are feeding them the breakfast of champions, a 10-52-10 fertilizer, after all.  What more could a Hibiscus ask for?

I have to say, when I look at the blooming Hibiscus I purchased a few years ago from Winn Soldani's Famous Hibiscus farm (www.fancyhibiscus.com), I just can't take my eyes off them.  These are gorgeous shrubs.  So I think you ought to take action here, my friend, quit being patient about it, and move them somewhere that will make you both happy.  Because I don't think you should spend another winter without enjoying the flowers on those shrubs.

What do you think?  Is there someplace you can put these, perhaps even a large pot to keep them from being potbound or suffering from fertilizer salt buildup over time?  Life is too short to wait any longer for results.  Wouldn't you agree?