Hibiscus Care

Note from Richard: I did not write this article (I bet you can tell!) but it does have some very good information in it. I plan on writing my own take on hibiscus - without all the mumbo jumbo. But because I am asked every season about Hibiscus and their care I decided to include this one. A company by the name of Zoes Tropicals is responsible for this article. You will see a link to their site at the end of the page.

The tropical hibiscus, Hibiscus rosa-sinensis, is a tender perennial cousin of the hardy mallows. It is usually considered to be limited to Zones 1 - 9. It is the state flower of Hawaii, and the national flower of Malaysia. The original tropical hibiscus had a red flower, but breeders have produced a wild variety of colors including tricolors of pink, orange and yellow. Recently, many hybrid polyploid plants with multicolor or double blooms have been developed.

Other members of the mallow family, or Malvaceae, are the Rose of Sharon, the musk (Malva moschata), indian (Abutilon theophrasti) and rose mallows (Hibiscus spp.), the lowly cheeses plant (M. neglecta), and the flowering maple, a house plant. The flower structure of the mallows is pretty consistent, being 5 petals with a long, tubular combination stamen and pistil. The seed pods are always chambered, with large seeds.

All mallows are somewhat mucilaginous, i.e., slimy. The original "marshmallows" were actually made by boiling down the sweet mucilage of the marsh mallow (Althea officinalis). Okra, source of file powder, the proper thickener for gumbo, is a mallow. Some of the red in Red Zinger Tea, a popular herbal tea in the 70's, was red hibiscus flowers. Tropical hibiscus are listed as food sources for desert tortoises by the California Turtle and Tortoise Club.

Pot Culture of Tropical Hibiscus

Tropical Hibiscus may not be grown outside anywhere that experiences hard frosts, although light frost may be survived if the plant is cut back to the ground and heavily mulched. However, hibiscus may be grown in pots and moved indoors for the winter.

Light Needs

The plant should get several hours of direct sun, as in a window with southern exposure. Plants may not flower much, if at all, under winter light, but I have noticed that such flowers as there are last longer under a shorter day regime, sometimes as long as 3 days. In the summer, you can move them outside gradually, and let them flourish. After summer, you must prune them back before moving them inside again. Be sure to prune the roots, too. This may be a good opportunity to repot.

If the indoor spot you have selected is too dark, the plants will shed their leaves after moving. After the leaves have been dropped, the plant will attempt to grow new leaves which are calibrated to the new light level. This level may be too low for the plant to survive or grow well, and you may need to find another place. If this is not possible, you may also try supplementing with artificial light. You may also try pruning the plant back harshly. The less woody tissue the plant needs to support, the less total photosynthate it needs, so a smaller plant may survive where a large plant would die.

Any plant which has been grown indoors can be overwhelmed by too much light. There are many physiological differences between leaves grown in high and low light, and the plant's response to a radical change in light regime is to drop the old leaves (see abscission) and try to grow new ones. If the plant does not have enough stored sugars to make this large effort, it will die. If the leaves appear bleached immediately after you move it outside, it is getting sunburned. Since the bleaching means that the chlorophyll has been destroyed, it is better to acclimate in all cases.

To acclimate your plant to the higher light levels of summer, you can limit exposure to light in time and intensity. Put the plant some where that it will get a short period of direct light in the early morning or late evening, when the light is less intense. You may also put it in the shade of a tree or a lathe covered patio for some of the day. As new leaves appear, give it more light so that they are formed in the higher light level.

Potting Soil and Fertilization

If you have received your hibiscus from us, chances are they are rootbound. These plants have grown and been cut back repeatedly. They have been fertilized twice a week and watered constantly. As long as the roots can find the resources the plant needs, they really don't care if they are cramped or not. If you are not going to maintain an intensive fertilization and watering regime, you may want to repot.

Potting soils for hibiscus should be light, and not too acid. A mixture of peat moss and perlite, such as a commercial potting mix, is good.

Hibiscus should not be overwatered, but they are thirsty plants. I find that clay pots, although esthetically pleasing, dry out much faster than plastic pots. It is important that the plant not become water stressed during graft formation. During healing, both stock and scion need water for callus formation and cell growth; water stress will delay the graft union. Until vascular connection is complete, a process which takes quite a long time, the scion will receive only a fraction of the water it would normally; dessication that stresses the stock might kill the scion.

Information on fertilizers is a little contradictory. Taking an N-P-K (Nitrogen, Phosphorus, Potassium) ratio of 1-2-1 (as in Miracle Grow) as the standard for most garden plants, most recommendations for hibiscus are much lower in Phosphorus, more like 3-1-2 (as in Osmocote or Nutricote). When the plants flower, they will need more Phosphorus. Some growers recommend foliar feeding of phosphorus fertilizers, as phosphorus is suspected of tying up soil nutrients. You should check out cultural recommendations at the sites below for more information.

This information found at www.floridaplants.net.