It really could be either, Alice. It's more likely to be too little water, especially given how hot it has been lately, but hibiscus don't like to be really wet, either.
Hi Doug, The ones in the yard get water 4 times a week with my sprinklers and when it rains. The ones in the pots,I only water when they are just starting to get dry. This seems to be an on going thing with this
The ones in pots are much more vulnerable to the heat than the ones in the ground. It would not surprise me if you saw more yellow leaves on those. If you don't think it's a water issue, it's possibly a mineral deficiency, likely iron, possibly magnesium. In that case, you'd want to apply iron chelate or magnesium sulfate (here's a case where Epsom salts really would be beneficial).
Its kind of the same all around. I have about 3 mature tress that are planted and are full of yellow leaves, the ones in the pots are on my lanai, and I water them probably every other day or when I see them starting to dry up
I added to my answer above. It sounds like you might have a mineral deficiency.
Thanks Doug I'll try the magnesium I did that to my robelinis when they had frizzel palm and it cleared it up, thanks again
Alice, mine did the same thing when it was in a self watering planter. It sucked the water as it needed it, and it took plenty. I found that by adding 2 tbsp of epsom salt to the water stopped the dying and yellowing leaves. It happens because of a magnesium deficiency, of which is not a readily available mineral. Just add it to the water, and give it a good stir. I also added a fertilizer spike to mine, every couple of months. The spikes are slow release, so they last longer than most would think. Just because you can't see it, doesn't mean it is still not working for you.
Hi David I put some magnesium around all of them the other day hope that works Thanks for your input
Alice they are using a lot of energy blooming they need some more food! :)
I can't help as far as answering this post but would like to know when I can trim my hibiscus back? I have one that's growing up..its at about 3 1/2 feet tall right now but not bushy, The plant is loaded with blooms.
Hibiscus don't like erratic watering. They will yellow out with either too little or too much. Do you know how much water the ones on your sprinkler system are actually getting. Your grass needs 3/4 of an inch of water once or twice a week but the hibiscus needs at least 1 1/2 inches of water at a time so you are probably not getting enough water from your irrigation system. If the ones on the irrigation system have been in the ground for a couple of years you could probably disconnect the system and just hand water when needed.
The yellowing looks ugly but won't really hurt the plants. Good luck
@Sheryl Grimm you will get more responses if you post your question as a new question using the red "post/ask" button at the top of the page. I cut my hibiscus back in February, after any chance of frost. You're going to lose all your blooms if you prune now.
We had them in AZ. and we put iron around the drip line. That is what they needed, It did the trick!
Would the same thing be true of Rose of Sharons? I have the same thing happening to them. I am in NC and we have had a lot of rain this summer. Or could they be low in some mineral?
Debbie , it can hurt to try! Good luck!