Ah yes, the actual subject of this thread. The Hibiscus species in question is H. sabdariffa (just click on the link in the first post for the low quality study that mentions this). As to apollog's feeling compelled to indulge in name-calling because I "distort" discussion in threads, the history of our interactions is marked by his misquoting and mischaracterizing what I've said. The discussion on "alkaline water" in particular features the usual apollogian tactics of going off into tangents, failing to address the multiple expert opinions I cite (pretending that I alone hold such opinions) and above all, volleying insults. Somehow I manage to handle these distortions of debate calmly without indulging in personal attacks. I am able to do this because I have evidence on my side and don't need to distract people by assaulting the character of those with whom I disagree. "Ad hominem abusive: Ad hominem abusive (also called argumentum ad personam) usually and most notoriously involves insulting or belittling one's opponent, but can also involve pointing out factual but ostensibly damning character flaws or actions which are irrelevant to the opponent's argument. This tactic is logically fallacious because insults and even true negative facts about the opponent's personal character have nothing to do with the logical merits of the opponent's arguments or assertions. This tactic is frequently employed as a propaganda tool among politicians who are attempting to influence the voter base in their favor through an appeal to emotion rather than by logical means, especially when their own position is logically weaker than their opponent's. Examples: "You can't believe Jack when he says God exists because he doesn't even have a job." "Candidate Jane Jones's proposal X is ridiculous. She was caught cheating on her taxes in 2003." Employing fallacious tactics like ad hominems and strawmen (creating arguments your opponent has not made which are easier to tear down than what he actually said) are excellent evidence of how barren one's position really is. Amen.

Just some fertilizer info to help with the confusion: You might find the formulation 12-4-8, but 12-6-8 is one I've never seen. I'm not saying it's not available SOMEWHERE, but it's not readily available ....... and it's not a high-K (potassium) fertilizer. A high potassium fertilizer for Hibiscus would be something like 12-4-18 or 9-3-12. The NPK % 14-14-14 is only one of the hundreds of the CRF fertilizers offered by Osmocote, and 1:1:1 ratio fertilizers like 14-14-14 are not well suited to hibiscus in containers because you can only supply adequate amounts of N or K by significantly over-supplying P, and hibs rebel at P excesses. There is no "right" fertilizer for Hibiscus growing in the ground unless its formulation is determined by the results of a soil test and the testing facility knows you'll be growing hibiscus. W/o having your soil tested, whatever you use as fertilizer is essentially a shot in the dark. Generally though, in a very high % of the US, it's best to use phosphorous-free fertilizers that are high in K (potassium) for hibiscus growing in the landscape as opposed to pots. Al

It's difficult to quantify watering frequency with a number. There is a myriad of factors creating different microclimes even indoors. However, generally, plants wind down in winter and hibiscuses lose their leaves in winter for a reason. As Luis said, stick your finger in to feel the moisture in the compost and don't water unless it's really dry. Overwatering is usually one major reason killing plants in winter.

Yes, tropical hibiscus can lose a lot of yellowed leaves due to pests such as spider mites as well as other pests like mealybugs, aphids, thrips, etc. It was hard to find anything in the pictures after your cleaning. Many of these pests leave clear, sticky honeydew excrement on top and-or below the leaves, which ants and other pests are attracted to. The sticky honeydew excrement then turns black/brown due to simple opportunistic fungal infections on the honeydew. New foliage can return in a few weeks. In most cases, a strong shot of water, horticultural soap or neem oil is effective in reducing the population. You can also rinse off the plant to get rid of soft-bodied insects, like some aphids. For harder bodied pests, some people use diluted rubbing alcohol sprays (always test in an inconspicuous corner). There are also several insecticides specifically formulated for the pest but identify the pest as best as you can (add pics of the pest or take samples to a local plant nursery. There is also a pest identification forum in Houzz. For spider mites, you will need a magnifying lens to identify them as they are so tiny. For example, there are some white dots in the last picture that could be spider mites, dust or other stuff. The potting soil in picture 2 seems to be a little dry. We are close to the start of warm temperatures so be ready to ramp up your waterings to "summer levels".