Images. Please provide a close-up of the symptoms you described and at leadt one image of the entire plant, including the pot.

How do you decide when it's time to water your plant?

Does the pot have a drain hole?

If there is a collection saucer, are you allowing the plant to reabsorb the water that collects in it?

When is the last time you fertilized? What did you use?

How long have you had the plant?

Hibiscus are one of the few plants that actually need a special fertilizer; this, because they use more potassium than nitrogen, whereas most plants use around 6x as much N as potassium. Hibiscus use only a very limited amount of phosphorous, so "bloom-booster-type fertilizers' should always be avoided. Hibiscus also have very aggressive root systems, and need a full repot annually (in mid-spring) to be at their best. When they become seriously rootbound, they often shed inner foliage (close to the trunk) such that in the end all or almost all foliage is concentrated near branch tips. The foliage close to the trunk often goes through a period of resorption, during which mobile (in the plant) nutrients and other biocompounds are reclaimed by the plant to support new extension growth. This results in breakdown of the green pigment chlorophyll, which normally masks other pigments, and provides opportunity for insect pests and disease pathogens to infect the plant. The reason is, part of the shedding process includes individual leaves being walled off from plant processes/ functions by a layer that forms at the base of the leaf.

These questions and information take a stab at trying to figure out what might be going on with only the limited information to go on. Answers to the questions and images might provide insight showing the issue is unrelated to anything I said, but please mention anything I said that contrasts with how you actually care for the plant. Knowing what isn't the cause can be very helpful in determining what IS.

Al

Thank you so much for your reply!

How do you decide when it's time to water your plant?

I wait until the soil is very dry but before the leaves on the plant droop

Does the pot have a drain hole?

Yes

If there is a collection saucer, are you allowing the plant to reabsorb the water that collects in it?

Yes it re-absorbs it, but last time I watered it I ran a lot of water through it and down the drain to try to wash the soil in case I had over fertilized or there was something bad in the soil.

When is the last time you fertilized? What did you use?

YAbout a month ago. I used the recommended amount of water soluble miracle grow. I've been doing that for about 3 months.

How long have you had the plant?

1 year

It really seemed to start after the bug infestation. Is a pyrethrin spray poisonous to hibiscus?

Was the fertilizer 20-20-20?

Pyrethrin itself is probably not an issue, but the plant might be sensitive to the vehicle used to deliver it. By vehicle, I mean the substance the insecticide is dissolved or suspended in. Example: If Epsom salts make's a good solution for a foot bath, water would be the delivery vehicle. Did you spray the pyrethrin to the point of run-off and did you cover the soil? Often, insecticide containers' labels list plants that might be sensitive to the product, or an online search will turn up the info.

I'm not sure how far you're willing to go to try to turn things around. My thoughts: If you want to try, I would purchase 2 products, 1) Foliage-Pro 9-3-6 fertilizer 2) ProTeKt 0-0-3, which contains 3% potassium and opalene silicon. The 9-3-6 will serve you well for almost any plant you would grow in a pot; but, hibiscus being an outlier in terms of its nutritional needs, you can use the ProTeKt to supplement the amount of K (potassium) you deliver. That has been my strategy for hibiscus in containers for the last 20 years +, and it works very well; better I'd say, than the "Hibiscus" fertilizers that use urea as their nitrogen source and lack some of the nutrients essential to normal growth. Further, I would do a full repot, including bare-rooting and root pruning, as the plant needs this annually anyway, to be at it's best. Then, I would make sure you're watering correctly and your watering intervals are appropriate; and you can do that by using a 'tell' you can make from a wooden dowel rod for a couple bucks. Ask if you want more info on that.

Al

Ok, I'll try the re-pot and fertilizer. Thanks for the help. What do you mean about the dowel as a tell?

Remember, repotting is more involved than potting up. There is a thread here on GW devoted to long term care of woody plants in containers. THIS should be helpful.

Using a 'tell'

Over-watering saps vitality and is one of the most common plant assassins, so learning to avoid it is worth the small effort. Plants make and store their own energy source – photosynthate - (sugar/glucose). Functioning roots need energy to drive their metabolic processes, and in order to get it, they use oxygen to burn (oxidize) their food. From this, we can see that terrestrial plants need plenty of air (oxygen) in the soil to drive root function. Many off-the-shelf soils hold too much water and not enough air to support the kind of root health most growers would like to see; and, a healthy root system is a prerequisite to a healthy plant.

Watering in small sips in order to avoid over-watering leads to a residual build-up of dissolved solids (salts) in the soil from tapwater and fertilizer solutions - which limits a plant's ability to absorb water – so watering in sips simply moves us to the other horn of a dilemma and creates another problem that requires resolution. Better, would be to simply adopt a soil that drains well enough to allow watering to beyond the saturation point, so we're flushing the soil of accumulating dissolved solids whenever we water; this, w/o the plant being forced to pay a tax in the form of reduced vitality, due to prolong periods of soil saturation. Sometimes, though, that's not a course we can immediately steer, which makes controlling how often we water a very important factor.

In many cases, we can judge whether or not a planting needs watering by hefting the pot. This is especially true if the pot is made from light material, like plastic, but doesn't work (as) well when the pot is made from heavier material, like clay, or when the size/weight of the pot precludes grabbing it with one hand to judge its weight and gauge the need for water.

Fingers stuck an inch or two into the soil work ok for shallow pots, but not for deep pots. Deep pots might have 3 or more inches of soil that feels totally dry, while the lower several inches of the soil is 100% saturated. Obviously, the lack of oxygen in the root zone situation can wreak havoc with root health and cause the loss of a very notable measure of your plant's potential. Inexpensive watering meters don't even measure moisture levels, they measure electrical conductivity. Clean the tip and insert it into a cup of distilled water and witness the fact it reads 'DRY'.

One of the most reliable methods of checking a planting's need for water is using a 'tell'. You can use a bamboo skewer in a pinch, but a wooden dowel rod of about 5/16” (75-85mm) would work better. They usually come 48” (120cm) long and can usually be cut in half and serve as a pair. Sharpen all 4 ends in a pencil sharpener and slightly blunt the tip so it's about the diameter of the head on a straight pin. Push the wooden tell deep into the soil. Don't worry, it won't harm the root system. If the plant is quite root-bound, you might need to try several places until you find one where you can push it all the way to the pot's bottom. Leave it a few seconds, then withdraw it and inspect the tip for moisture. For most plantings, withhold water until the tell comes out dry or nearly so. If you see signs of wilting, adjust the interval between waterings so drought stress isn't a recurring issue.

Al