Gnat-type bugs on indoor hibiscus plants

Credit: Thomas Tolkien

Q: I have 2 hibiscus plants. They summer outdoors (Windsor, Ontario) and winter indoors with a temperature of approximately 22°C. Within two weeks of coming inside, both plants get little white/beige flying gnat-type bugs. As a result, everything around the plants gets sticky as well.

This has been happening for a number of years.

Do you have any idea of what these bugs might be and how to get rid of them?

I believe this is due to “Whitefly” – a sucking insect that leaves behind a sticky residue and multiplies especially indoors under warm conditions. The simplest solution I suggest is to induce dormancy on your hibiscus by placing them in a cooler room, such as an unheated basement or garage, that doesn’t go below 0°C, with only limited light from a window.

The hibiscus leaves will probably dry up and fall off. However, the cooler temperature should slow down the whitefly’s ability to reproduce. As the weather outside becomes more consistently warmer in the evening (10 °C or warmer), bring the plant outside into a more brightly lit area.

Cutback top growth to desired length (by 1/3 to 1/2) to encourage more bushiness. The hibiscus can tolerate a light root pruning and be repotted into a new potting media. Alternatively, repot the plant into a slightly larger pot with new potting soil. Water gradually as new growth develops and fertilize as needed.

Fighting whiteflies or spraying hibiscus is an endless nightmare. Be careful because whiteflies can also infest other plants indoors.

Give your tropical plants a winter vacation!