Answer: It sounds as though your new hibiscus is going through a little stress. Conditions in your home might not be quite right for it to thrive. Here are some basics:
Hibiscus are tropical plants that need light and, perhaps more importantly, warmth to thrive. They prefer moderate heat and to continue blooming must have a few hours of direct sunshine every day. Place your plant in a bright South or West facing window. An Eastern window might also work. In winter watch out for cold drafts that can give hibiscus frostbite. In the winter you also need additional light. I use simple fluorescent bulbs, often referred to as low energy light, which screw into regular sockets. For best effect, place the light as close to the plant as possible.
Hibiscus like water but do not like 'wet feet'. The soil needs to dry up between waterings to protect from root rot. Make certain no excess water remains in the planter half an hour after watering.
For prolific flowering, hibiscus must have regular feedings every week during the growth period, March-October. Water soluble formulas can be used with every watering. I usually water 9 times with fertilizer and then flush with clean water the tenth time. This will prevent salt buildup in the pot. Never fertilize dried out plants -you may damage the roots.
Choose a fertilizer with a low phosphorous value: N (Nitrogen) 20 P (Phosphorous) 5 K (potassium) 20 is close to ideal. Too much phosphorous makes for many fine leaves but few flowers. Hibiscus also need trace elements, especially iron and magnesium.
The best time for pruning hibiscus is August-October, but some practice spring pruning with good results. Pruning is carried out not only to get a more harmonious plant but also to stimulate budding as hibiscus flower on new shoots. To create a good looking plant, try to establish 3-4 main branches. These should be sturdy and upright. Cut back 1/3 of the main branches and completely remove weak growth or sideways growing branches. You might decide to root prune at the time of replanting. Never prune off more than 1/3 of the root mass. It is better to err on the careful side here.
All hibiscus have yellow leaves now and then. A few yellow leaves usually only mean that those leaves are getting old and need replacing. If your plant has many yellow leaves it is stressed. The most common causes of plant stress are under-watering, drastic environmental changes or pest invasions, especially spider mites.
Hope this information is helpful!
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