Rajeev,

I've seen your post for awhile and wish I could help. I live in San Antonio, TX. I don't know if I can be of any help, but I will try.

I looked up Mumbai on the map and see that it's on India's west coast. I assume that the climate is very hot and dry, as opposed to India's eastern coast which would tend to be humid?

In the US, this would correspond most closely to Phoenix Arizona. (They typically have summers with at least 60 days over 100 degrees)

I also assume that you are growing Chinese Hibiscus and not the American "Swamp Hibiscus", which is decidous.

I'm not knowledgable about gardening in India, but from what I know India is a leader in composting.

In the US, this is what the average gardener would do: They would go to the store and buy potting soil. (It wouldn't have to be a special hibiscus soil.) The difference between potting soil and regular soil is: Potting soil is very light and porous and allows water to drain through the pot. This is necessary for any potted plant, because regular garden soil can quickly smother the roots of a plant. (I know because I quickly killed a small tree by using a "heavy" soil in a pot) The soil should be very light, and when you water, it should drain very quickly.

I've made my own potting soil by adding mulch (shredded hardwood) to soil. About 90% mulch and to only 10% garden soil. Compost is lighter than garden soil, but when used to make potting soil, I use 25% compost and 75% mulch.

I happen to have some hibiscus fertilizer handy. You can make your own. The hibiscus fertilizer has a higher potassium than regular fertilizer.

Our soils in Texas and the Southwestern US tend to be alkaline. They tend to be low in iron and zinc, and somewhat higher in phosphorous than soils in the Eastern US. This is due to hot, arid conditions.

This particular hibiscus fertilizer is formulated for Texas soils. It has extra iron and zinc and higher potassium than regular fertilizer.
The NPK ratio is
Nitrogen: 10%
Phosphorus: 4%
Potassium: 12%.

Potassium can be purchased seperately, and is commonly known as "Potash", here in the states.

Iron Sulphate can probably be purchased in India.

This fertlizer also contains some extra Copper, Managanese, Molybdenum and Zinc.

These trace minerals can sometimes be purchased. However, I would think hibiscus could do OK without them.

Iron is the most important mineral because it prevents the leaves from turning yellow.

Epsom salts, a common name of a compound, magnesium sulfate, are often used by gardeners. Epsoms salts can be purchased from a local pharmacy. A teaspoon of epsom salts per gallon of water helps iron become more available to the plant.

I assume the extra potassium in this fertilizer is to help with blooms and also improve heat/drought tolerance of the plant.

Hibiscus like generous watering. One thing they will do in hot dry weather is "drop their blooms" prematurely. One way around this problem is to also wet the foliage when you water them. They will enjoy the extra humidity on their leaves.

I hope that this helps a little bit. I hope that someone will answer your post that has some knowledge about gardening in India.

I'm from India originally but unfortunately never did any gardening there so I can't be of too much help.

But Mumbai has a very even, tropical climate through out the year. It's probably around 80's and quite humid. I think you wouldn't have to change much between summer/winter care. I've seen them grow all over in the desert areas of India so if it can do well there, I'm sure it would do well for you in Mumbai.

As for soil, I don't know what they use in India for soil but everyone has potted plants and hibiscus is a very common favourite and can be seen all over. So obviously the soil available and commonly used is okay.

THANKS pricklypearsatx and notanatural. It was indeed very kind of you both to post such informative replies. I feel the problem with my hibiscus is that it is not getting enough sun. They used to bloom in summer when it was hot and the sun was blazing. Now they don't bloom. My plants only get around 2 hours of sun (in summer this seemed enough). Maybe I need to buy some flowers which need less sunrays. THANKS once again.