The repellent is to be used on a hibiscus in a container on a deck.
According to the article below, combine 1 tablespoon of liquid soap to one quart of warm water.
https://www.gardeningknowhow.com/plant-problems/pests/pesticides/homemade-soap-spray.htm
Brown spots on Hibiscus leaf, what should insecticide should I use?
Not insecticide- Fungicide!
This is a soil borne infection that happens, normally, from saturated soils. You will need to treat with a fungicide/bactericide, and adjust watering habits if possible.
Make sure to let the soil dry out, thoroughly, down to about 2 or 3 inches between watering. This can help to prevent future infections.
Here are some articles that will help:
https://www.gardeningknowhow.com/garden-how-to/info/using-fungicides-in-garden.htm
https://www.gardeningknowhow.com/special/organic/biofungicide-information.htm
https://www.gardeningknowhow.com/garden-how-to/info/homemade-fungicide.htm
https://www.gardeningknowhow.com/garden-how-to/info/applying-bactericide-to-plants.htm
https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/how-to-care-for-hibiscus-plants.htm
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The color of a hibiscus was blue when I bought it, now it is a nondescript greyish color after planting.
This article explains it:
https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/hibiscus-turning-different-color.htm
I recently bought a Hibiscus (Hibiscus rosa-sinensis) flower but it has started drooping just 3 day later! I think the issue is either with the soil it came my watering habits. I water it daily but the soil barley absorbs the water and it dries out really quickly. I haven’t used fertilizer on it yet. The pot is also small. I still need to get one that’s the right size for it (it’s only been a week since I got it). So I was wondering what you recommend for healing it. Also, how should I proceed in the future to ensure it remains healthy (watering, pot size, soil type, location changes for cold weather, fertilizer)?
These experience shock quite easily. It will be best to show you some articles on their care for you to know what they require.
These will help:
https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/how-to-care-for-hibiscus-plants.htm
https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/outdoor-hibiscus-care.htm
https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/hibiscus-container-care.htm
There are black spots on the back of the hibiscus plant leaves where the leaf and stem meet as shown in the photos. What are these and how to get rid of them?
That would be sooty mold. This happens from aphid infestations. Here are some articles that will help:
https://www.gardeningknowhow.com/plant-problems/pests/insects/homemade-aphid-control.htm
https://www.gardeningknowhow.com/plant-problems/disease/how-to-get-rid-of-sooty-mold.htm
https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/how-to-care-for-hibiscus-plants.htm
I assume this is a pest, what do I do
Yes, this is definitely the work of a pest, probably Japanese beetles. You should spray your plant with horticultural oil as soon as possible, and clean away all the leaves that have been damaged. This article will give you lots of information on how to deal with the problem:
https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/pests-on-hibiscus-plants.htm
https://www.gardeningknowhow.com/plant-problems/pests/insects/skeletonized-plant-leaves.htm
Our temperatures are hot here in Arizona, how often should I water it & feed it with Miracle Grow . I keep it in the sun part of the day is that o k or should I keep it in the shade
I think this article will answer all your questions:
https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/hibiscus-leaf-drop.htm