Over Fertelizer

[Kathleen]

Been a while since I have posted.  That's because all was going well...until now.  Once the hot summer months subsided and the torrential  rains stopped my hibiscus plants all began to thrive.  Late fall and throughout the winter brought me the rewards I have been waiting and striving for all year - big, beautiful blooms!  Come the first of March I decided to give everybody a good fertilizing with Osmocote which is supposed to last 6 months.  What a mistake!  First, they all stopped blooming.  Then the leaves began to yellow and fall off.  Three of the young plants have actually died and three others are still on the critical list. The survivors aren't doing well either.  They are getting new leaves, but they are small and curly and no buds at all. My question is, how do I bring them around again?  I know I should never have anything but HVH time release...now I am paying the price.

[Kyle]

Kathleen,
  I'm not so sure Osmocote was the reasoning for the issues.   I know of a few types of Osmocote in which one is 14-14-14 and Osmocote Plus is 19-6-12.  These are not bad ratios for hibiscus but not the most ideal.
  They also make several other types time released formulas too.   I think Osmocote is slightly acidic which benefits hibiscus.
  I know someone that uses Osmocote on young hibiscus seedlings and swears it's awesome and easy to use.    He is a well known grower/hybridizer.    My brother uses it on many of his perennials throughout the yard and likes it as a good all around fertilizer during the spring and summer months in Ohio.
If you are using the time release granules,  temperature effects how the nutrients are released.   For example if the temps are 80-90F it may only last 3-4 months because the heat releases the resin.   
My brother works the granules into the top couple of inches on the top soil rather than pouring the granules on top of the soil like regular time release fertilizer.
   Sorry for asking but did something else change in March?  Did it become so warm that they need more water or the opposite where they may have had to much water?   I'm trying to think what could make the leaves small and curly.   
 To bring them back around check the basics.  Are they getting enough or too little water with the season change? Big taller bushes will demand more water as they get bigger.  Are there drain holes in the pot and can you see water flowing out of them?   
You seem to have a better understanding of watering and drainage and have become more aware what to look for.   
Best of luck, hope we can help out.
Kyle
 

   

[Gil]

My plants are also experiencing the same conditions. They all were blooming great from Jan-March. In mid March, I noticed lots of mottled yellow leaves. I suspected spider mites, but saw no evidence. Since I also had a few aphids and mealy bugs, I gave them a spray of Bayer 3 in 1. Leaf drop got worse. The following week, I hit them with Floramite, but the leaf drop continued.

Then I thought about fertilizer overdose (since they were being fertilized daily through my drip system. Cut the amount of fertilizer in half, but that also didn't help.
Finally, I just turned off the drip system and flooded them with just water. Now they are starting to look better with lots of new growth (just no blooms). I'm continuing to leach the soil of any fertilizer buildup (flood the hell out of them). The HVH page on feeding mentions Phos overdose causes chlorotic leaves and shuts down bloom production.

Not sure when to start up fertilizer again, but the more I stick to water only, the better they look (just no blooms growing).
I just bought a soil test kit (80 tests) for pH and NPK. Haven't gotten it yet, but will do some tests and also compare the output of my drip system with a TDS meter.

200 plants and no blooms for the entire month of April and still none as of today!

[Kathleen]

Thanks for the input Gil.  Sounds like you experiences the same thing I am going through.  I only have 20 or so plants...I can't imagine trying to take care of 200!  I thought I could save myself some time using the Osmocote that is supposed to last for 6 months; instead all I managed to do is kill half a dozen plants.  Three more are still on the critical list.  All of them are still trying to recover.  I scraped off the little fertilizer pellets from the top of the soil on all the plants and have been watering for the past 6 weeks or so with just water.  The larger plants, those that are over 3 feet tall, seem to have benefited from this and are growing new "healthy" leaves (no blooms yet).  The others are in 4 and 6 in pots and are under 2 feet.

I ordered some more HVH Super Blend fertilizer and worm castings.  I just this morning used those products on the healthy plants.  I don't know what else to do for the others.  I'm afraid to use anything else on them as they are so fragile now  I even thought of repotting them with fresh potting mix; but then again, I'm afraid to shock them further.  Any suggestions    anybody?

Kathleen