(Editor's Note: This article was originally published on January 21, 2008. Your comments are welcome, but please be aware that authors of previously published articles may not be able to respond to your quesitons.)
The tropical hibiscus or Hibiscus rosa-sinensis is a member of the Malvaceae or mallow family. This national flower of Malaysia is closely related to shrubby althea (rose-of-sharon), hollyhock, hardy hibiscus, and cotton, among others. Most people also think of it as the state flower of Hawaii, but that is actually a native species of hibiscus, H. brackenridgei. With thousands of colors, a variety of bloom sizes and configurations, and a multitude of plant sizes as well, it is no surprise that the tropical hibiscus is one of the most popular flowers on the planet. But don’t let the name fool you. Tropical hibiscus is quite happily grown in pots, so they are easy to move into greenhouses or basements for overwintering, or can easily be grown as annuals.
The easiest way for the average gardener to add this lovely flower to their gardens is through cuttings. Growing from seed is often a timely and frustrating way to discover that those 6 to 18 months of waiting have produced a flower that doesn’t look at all like what you were expecting. So let me show you an easier way. Cuttings are quick, usually good for the parent plant, (since occasional pruning keeps the plant in good shape and helps to promote blooming), and the color of bloom you get will be the color that you wanted.
The first thing you will want to do is prepare your pot. The size of pot you choose will depend on how many cuttings you will put in it. For some reason, hibiscus cuttings seem to do best when there are several rooting together. Make sure that the pot is clean, and then nearly fill it with your growing medium. Many people recommend perlite or clean gardener’s sand, but I find that potting soil works best for me. With a stick or pencil, poke a hole for each cutting you will be placing in the pot. Now you are ready for the new cuttings.
You want to find a fairly sturdy, but not thick branch of the parent. Take a cutting just above an "eye", and in the direction of growth that you want to encourage. Your cutting should be about 8 inches. Then with a sharp razor or very sharp knife cut again right through the middle of an "eye" or leaf node. Cut off most of the leaves, leaving only a few at the top of your cutting. Cutting the leaves off, rather that pulling them, creates less damage to the stem, which can be a way of inviting disease.
Hold the cutting in a rooting hormone for 10 seconds or so…giving the hormone a chance to adhere to the stem. Gently place the stem in the prepared hole, keeping as much hormone on the stem as possible. When you have all your cuttings in the pot, you can place it in a clear plastic bag in a shady spot with only limited filtered light. If you live in a humid area – or have room in your bathroom, the plastic bag is not necessary. But the filtered light is. Too much light will cause the cutting to try to grow UP instead of concentrating on root growth. The few leaves you left on the top of the cutting will help the transpiration of moisture throughout the new plant.
Once you see new growth – usually 5 or 6 weeks, separate the rooted plants with a gentle stream of water and put them in their own pots, or in the ground, whichever suits your garden. Pots generally work better at this stage, because you can ease the new plants into sunshine a bit more each day. Eventually you will want your new tropical hibiscus to have full sun for the most blooms. I have seen blooms in as little as two weeks from re-potting, but the average is around 4 to 6 weeks.
The gorgeous blooms may only last one day, but there are always new buds waiting in the wings. When frost threatens, you will need to move them to a warmer area, but these lovely tropical beauties will reward your efforts by continuing to bloom for many years to come.
They may be fleeting and fragile…but they are definitely fabulous!