Whats causing leaves to do this?

[dayvedayve]

  I am having alot of my hibiscus leaves doing this.  Is it care or pest?  Temps are lows in the 60's and highs in the 80's.  They are under a shade cloth so no direct sunlight.  No bugs that I can see.  No bud loss and I have been able to get a few seed pods.  Its on seedlings and older plants.  Aybody got any ideas of what to do.

[Doll]

Since the damage seems to be confined to the edges of the leaves, I'm thinking fertilizer burn.
There is a section here about fertilizer burn.
http://www.hiddenvalleyhibiscus.com/care/feeding.htm

[dayvedayve]

It has been a few weeks since I did fertilize. I used a miracle grow feeder attacked to a garden hose. Could it be something in the water? We have city water.  Not enough rain to save any water. Was thinking about putting water in a large container and letting it sit for a few days to let the chlorine fade. 

[Doll]

I don't think it would be the fertilizer if it has been that long. Chlorinated water has never caused any damage on my plants.

[Doll]

dayve, if I remember correctly you live along the Gulf coast. Were your plants exposed to those high winds from that last cold front?

[helixturnhelix]

Hi Day,

This is 100% nitrogen/salt burn.  Since you have been using the spray miracle grow, which is a 20-20-20 blend you likely over fertilized a few weeks ago and are just seeing the results of it.  This blend of fertilzer is a bit too high in nitrogen and phosphorous ( 1st and second numbers) for hibiscus.  Also using the spray nozzle doesnt allow you to regulate the concentration of fertilizer.  Check out the hvh fert blend for numbers to look for in your fertilizer.  This is especially true if you have very hard water with alot of calcium carbonate.  I had the same thing happen to me with hard water.  Adding a little bit of vinegar when you water will drop the pH and dissolve remove some of the calcium carbonate in your water ( if it is there). I would just water with this slightly acidified water for a few weeks and see if things improve.  Only when you don't see any symptoms you can try really dilute fertilizer and work your way up.  I hope this helps, let us know how it works out for you!

[davidwood]

Reading what Cris says about the 20-20-20 I hope and think I have done right. I am not able to buy fertilizer from Charlie as I cant import it, but I have been able to get hold of some 20-20-20 and some 12-0-40+3CA [no idea what the CA means] all in 500g jars. Now Charlies mix is 17-5-24 so what i have done is mix 2x 12-0-40 and 1x 20-20-20 this gives me 44-20-100, divide by 3 = 14-7-33. I could by mixing them one to one and get  16-10-30 but I worry the middle number is a bit to high [also I have a lot more 12-0-40], I know in both cases the last number is a bit high but beggars cant be choosers, also as I cant get Booster from Charlie either so I am hoping I will be ok with a bit extra potassium.
If anyone sees any great flaws in my thinking please point it out.

[dayvedayve]

Doll, I live in Bridge City.  This started before the cold snap.  They were being blown around pretty good.  The greenhouse gets started this weekend

We do have hard water.  I ussually dont have to water as much as I have been, but this summer has been bad.  Doll knows what Im talking about.  High heat and very little rain.  Is the problem limited to the leaves or is this from the soil?  Would watering the soil prevent this burn

[Charlie]

The photos show classic fertilizer burn. I remember using a hose end fertilizer mixer at a friend's house a long time ago and was dismayed to see that it "pulsed" the fertilizer. We used a fertilizer with a blue dye in it and you could see spurts of blue colored water followed by spurts of clear water. If that is the case with the one you used then it would result in some pots or plants getting heavy doses and others getting weak doses.

However it happened, the plants will most likely recover after dropping the affected leaves. You can flush out the soil by overwatering once so that the excess water removes extra salts/fertilizer from the root zone. Hibiscus are surprisingly tolerant of chlorine and the amount in water would not cause this.

Charlie

[Doll]

dayve, I had to look up Bridge City on the map. I see you live to the east of me right along the Tx -La border. I avoid using fertilizer at full strength in our hot climate. I usually feed my plants 2-3 times weekly at half strength.

[dayvedayve]

Yep, Bridge City is a little bedroom town sitting on Sabine Lake.  I only fertilize once every 2 weeks.  I'm gonna have to change that.  This is the first year I used the sprayer with the granules.  I used to use the liquid attachment that miracle grow came out with, but after this i'll be using the watering can again.  I have over 150 hibiscus in pots and was looking for the easy way. That will teach me!

[Charlie]

Dayve, you may have noticed that some of the forum people use a fertilizer injector to mix the fert into their irrigation water for their drip systems. With 150 plants you may want to think about setting up such a system. But, you can also use the EZ Flo injector with a hose instead of attached to a drip system. It's more accurate at mixing than the hose end type. If interested, just google EZ Flo and you will find info about it.

Charlie