Hibiscus

(Question)

I have a big hibiscus that is just flowering now but will have to come in soon with. Weather changing. If it is full of buds now, do I cut it back and how much, it is 3 ft tall so healthy but will put under grow lights for the winter, any suggestions will be much appr3ciat3d and thanks in advance

(Answer)

Your plant is most likely a Hibiscus rosa-sinensis, or Chinese hibiscus. It is a frost tender evergreen hardy to USDA Zones 10-11. This plant makes an attractive outdoor plant in the summer, but must be brought indoors in the fall before the temperatures drop below 12°C.  Overall, it needs good ventilation and protection from direct sunlight.

Once you bring your hibiscus indoors, it prefers somewhere warm and humid, ideally with minimum night temperatures of 7-10°C.  As long as you keep it away from direct sunlight, as well as any draughty areas or heat sources such as radiators or fireplaces, it should be fine.

These plants love humidity, so you can place it on a tray filled with damp gravel or pellets that will help maintain a humid microclimate around the plant. You can also mist it with water.

As plant growth starts to slow, you can reduce watering, only watering when the top layer of soil is dry. At this point, stop feeding your hibiscus. Your plant will probably go semi-dormant in cooler conditions.

As for pruning, wait until early spring to do this. Sometime in February or March, cut back the previous year’s growth, leaving an attractive framework for new flowers to form.  You can cut back some of the stronger growth up to 4-7 cm above the base. Remove any thin shoots.  If you want a bushier shrub, you can pinch the tips. In your case, I would let your hibiscus finish flowering now and wait until the spring to cut it back.

In addition to pruning in the spring, you can also re-pot your hibiscus using a peat-free, houseplant soil formula.  As light levels and temperatures start to increase, start to increase watering. This will help stimulate growth. About six to eight weeks after re-potting, you can also start to fertilize weekly with a houseplant fertilizer.

Good luck!