Thank you for the comment! I will try less water. It has been upper 80s and sunny all week and I have it out in full sun so I thought I'd water at least every other day.

It is a water issue. Heavy rains turn my leaves yellow on my standard hibiscus. Water only when soil is dry down to 4 inch depth.

NK - you can get some relief from heavy soils that hold too much water by adding a wick to your pot. Simply push an absorbent wick through the drain hole into the soil. Also, tipping the pot at a 45* angle after it has reached container capacity will remove a lot of the excess water. 'Container capacity' is a measure of how much water the soil holds immediately after it stops draining after being fully saturated. There are other easy ways you can put science to work helping you eliminate water that limits root health/function if you're interested .......

Al

"Watering on a schedule will bring certain doom to your hibiscus." Even though some variation of that thought is widely repeated by rote, it's a very broad statement. Why is it true/what makes it true?

Hint: It's not true, but you could have made it true with a little qualification. Lacking that measure of qualification it has to be viewed as a false. It's sort of like saying driving 100 mph will bring certain doom. Likely true if you mention the oncoming Mack Truck immediately off your beam, but must be taken as false w/o that little qualification. BTW - what I said about watering on a schedule isn't pivotal on wordplay - it involves a little science.

Al

The picture NK posted in the OP illustrates that somewhere near 20% of the current foliage volume is chlorotic, which doesn't include that fraction of leaves that have already been shed. In my book, that's an issue the cause of which should be of concern and is worth looking into and correcting, rather than being ignored or over-looked. After all, what defines out proficiency as growers is nothing more than our ability to identify and correct those conditions that are limiting to our plants. Ignoring potential limitations because they at first don't appear to be acute is a good way to ensure we have plenty of acute issues to 'fix' that we'd rather not.

I water on a schedule, and I talk about it very frequently on various forums and explain why I can, w/o suffering anything resembling certain doom or even slight limitations you can definitively associate with over or under-watering. I've BEEN watering on a schedule for 30 years or more, and have posted images of hundreds of perfectly healthy plantings, which raises the question, why aren't my plants exhibiting symptoms that they're circling the drain and waiting to go down the tubes? The only way you could make that claim: "Watering on a schedule will bring certain doom to your hibiscus" [or any other plant], is if you make the ASSUMPTION the choice of soil providing a home for the roots of the plants that make up the planting is water retentive to the degree that it is limiting at container capacity. Then, if we're to offer advice based on an assumption, it's best to define what that assumption isa instead of allowing others to make still another assumption that one size fits all.

Growers who understand something of soil science would be sure to QUALIFY their statements because it's easy to make soils that are NOT limiting due to a tendency to retain excessive amounts of water at container capacity ..... which is precisely why I can water on a schedule. ANY person repeating the claim initially made CH&G w/o some serious qualification of that claim is calling attention to the fact that not only is the statement erroneous w/o proper qualification, but also to the fact they really don't know why the advice is being parroted. Obviously, that I water on a schedule w/o acting as conductor of my own plants' melody of doom raises serious questions about the validity of the claim as the one size fits all manner in which it's being used. I can explain why I CAN water on a schedule, but that I do w/o limitations resultant of doing so leaves proctors of the claim at a distinct disadvantage when it comes to explaining why I can't.

Al

most people can not simply water on a set schedule due to variations on when a plant dries out. In my area - i water by hand and my plants are potted - i have to be very careful about upcoming weather changes. if the temps are going to stay 80 plus - i can water everyday no problem, the second the temps move to mid or low 70s i have to pay close attn to how wet the soil is. since temps can very by day - and I do have to work all day - this leaves me facing the choice of over water a bit now or leave the plant under watered and find the leaves drooping and wilted when i get home. yes there is the drip system and that would greatly improve my watering schedule - however i don't own my residence and don't feel the need to shell out money for said system yet. so yes i face a lot of yellow leaves - overall no big deal. the plant sheds some leaves, new ones grow in for the season. as long as it stops in a few days. just have to figure out which direction you need to go - and watch for signs that its not watering causing yellow leaves - thats when things turn bad quickly.

i mostly water based on weight (soil dampness) and weather conditions, and plant performance in current location.

FWIW - it's the water soils hold BETWEEN soil particles near the bottom of the pot in a saturated layer called a perched water table that limits your plants by robbing roots of the oxygen needed to function efficiently. Build a soil that doesn't hold perched water and you're no longer a slave to your soil's dictates. I water AND fertilize succulents in pots located right next to plants that won't tolerate a dry rhizosphere on exactly the same SCHEDULE; so you can see where the statement "Watering on a schedule will bring certain doom to your hibiscus" needs qualifying.MUCH better to say, "Watering on a schedule CAN be problematic .....", then go on to explain when it is and when it isn't a problem than to issue all-encompassing statements that must be taken as false for lack of appropriate qualification.

Al

yep - and i have been working towards a mix that holds enough water to get though a hot 24 hr period with out drying out too fast nor holding too much water - getting better at it. the type of pot you use plays a role too - certain ones just seem to hold more water even with the same potting soil - i try to put those ones in more sun than the others. always a different factor involved.

...... and as far as pots with no drainage holes in them - they're not a good idea ...... at all. Chief among the reasons are the facts that A) if it rains or you happen to over-water, there's no practical fix, other than waiting until a suppressed root system + what evaporation occurs brings the moisture level in the soil back in line with something more tolerable for the plant, and B) there is no way to prevent the build-up of mineral salts from tap water and fertilizer solutions from becoming too high and fertilizer nutrient ratios from becoming badly skewed - especially if the grower is using a fertilizer the NPK %s of which don't closely represent the ratio at which the plant actually USES the nutrients. While a skilled grower can manage to keep plants in pots w/o drain holes happy for some time, eventual decline due to high TDS levels and skewed nutrient ratios is inevitable.

Al

A pot without drainage will also encourage anaerobic decomposition of organic matter very quickly. I bet if you take out the plant it will smell pretty awful near the bottom. Logan - May be that is the reason you see yellow leaves after rain.

Al: Regarding the clay pot in your photos above - where did you get it? It has nice stand-offs and it is a very useful feature for proper drainage and wiring.

My hibiscus are also throwing yellow leaves but the heat is too strong, it is best in the morning sun only, if necessary irrigation and spray at noon, anyway will continue yellowing leaves at this time

I don't worry about overwatering, it never happens. My hibiscus don't get rained on, they are on the patio.

The pot is a bonsai training pot made by Tokoname in Japan from high-fired terra cotta (won't break if they freeze). I bought 10 each of 4 different sizes several years ago and have been using them for developing bonsai ever since. I keep an eye peeled for more, but unfortunately haven't been able to find them. Very high quality - like all the Tokoname pots.

Most growers are very quick to assign a cause to leaf loss and chlorosis before ensuring the basics are covered. Root congestion, improper fertilizing, and over-watering are the main issues that cause leaf shedding and chlorotic areas on leaves. Root-pruning every spring, using an appropriate soil (which goes a looooong way toward preventing over-watering) and an appropriate fertilizer should clear up the issue completely.

Al