By Melanie Mathieson
The Gardening Guru
The hibiscus flower is huge and delicate, as if they were made out of airy crepe paper—just one of the characteristics that makes among of the most sought-after flowering plants.
There are many incredible colour variations, which range from hot pink to plum. Others are bi-coloured or have attractive dark veins.
Another variation is the double-bloomed varieties that actually look like roses instead of the single tubular flowers we are most familiar with.
Whatever your preference is, you certainly can look for the hibiscus at this time of year, with other tropical plants, at local floral shops.
Hibiscus plants are divided into two main categories: the tropical flowering hibiscus and the hardy flowering hibiscus family. The tropical Hibiscus is not winter hardy in areas outside of climates such as the state of Florida, and is the variety we find sold as houseplants in our region.
This column will focus on the care of the tropical hibiscus as a houseplant. But it is worth mentioning that the hardy hibiscus is a perennial—hardy in U.S. growing zone 4 and, with extra protection, marginally hardy in U.S. growing zone 3.
Hardy hibiscus can be grown and enjoyed as far north as Minnesota and New York. Now this may be something to watch for in our local nurseries or seek through mail order.
Imagine being the first one in the district to actually be growing perennial hibiscus in our zone!
Hibiscus flowers are among the prettiest, most interesting, and easy-to-identify of all flowers. About 200 species are known to exist, and each one has its own unique kind of flower.
Hibiscus plants boasts multitudes of showy flowers up to eight-12 inches in diameter in shades of reds, whites, pinks, and bi-colours.
When looking at a hibiscus flower, you will see a particular arrangement of flower parts—a staminal tube surrounding a long, slender style that’s split into slender, spreading branches at the top.
This prominent pistil and stamen structure adds to the beauty of the hibiscus flower, which will appear and last for only one day.
While each bloom only lasts for one day, a healthy plant will produce ongoing blooms for a period during its bloom time, usually mid- to late summer when kept in the house as a houseplant.
The hibiscus is easy to care for as a tropical houseplant, though it is important to prepare the pot with the proper soil and find an acceptable location that will allow it to grow without a lot of stress.
This means without rapid temperature changes, drafts, near furnace/air conditioning vents, etc.
The hibiscus likes a spot with full sun for most of the day, and enjoys both the strong light and heat of a full sun window. A daily misting helps to keep the plant humid.
Hibiscus does best when planted in soils with lots of organic matter. This a good potting soil with peat moss added, often labelled as African Violet soil.
Hibiscus flowers appear on the ends of branches, so do not pinch off late in the growing season or the Hibiscus flower will be delayed into late summer.
Hibiscus like to be watered regularly, but cannot sit in soggy soil. The soil needs to dry between waterings to protect it from root rot.
Make certain no excess water remains in the planter a half-hour after watering, and always water with warm (room temperature) water.
Hibiscus also must have regular fertilizing every week during the growth period (March-October). As water soluble formulas can be used with every watering, they are the easiest to use. Just follow the directions on the package for watering of tropical or houseplants.
The best time for pruning hibiscus is between August and October. 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 three-four main branches which should be sturdy and upright. Cut back one-third of the main branches, and completely remove weak growth or sideways-growing branches.
The most common pests on the hibiscus are aphids and spider mites. Daily misting helps to keep both pests at bay but if they do take hold, the most effective way to get rid of them is showering the plant with lukewarm water using a strong blast from your shower.
Make sure to clean the underside of the leaves.
After the initial shower, keep it up at least once a week (obviously you can only do this if the plant is easy to transport back and forth to the shower). If the water treatment is not effective, use insecticidal soap to fight both spider mites and aphids, making sure to follow the directions.
Prevention is key here because once established, they spread quickly and damage the other plants in the house, too.
All hibiscus have yellow leaves now and then. A few yellow leaves usually only mean that those leaves are getting old and need replacing.
But 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.
Bud drop often is the result of drought or severe pest attacks, though it is unclear why some double flowering varieties are more prone to bud drop than other hybrids.
Tip: A hibiscus in bud should not be turned because then the buds almost invariably fall off. If the plant has buds, and turning of the plant is desired for more even growth, then it should not be twisted more than a quarter turn each time.
In the summer months, your hibiscus can be put outside and treated like an outdoor planter. Just make sure it is in a full sun location, it gets the right amount of water, and check regularly for aphids or spider mites.
And make sure you bring it back in the house in August before the night time temperatures drop below 50 degrees F.
Like many other tropical flowering plants, the hibiscus benefits from a winter rest period. You can achieve this by pruning back the plant to one-third its size, and placing in a low light area that has temperatures around 50 degrees F, for about three months starting in mid-December (or later if it is still blooming).
Water during this period only when the soil is completely dry.
After the three months, bring out the plant and place in its usually sunny location. In a month or so, you will have a plant that is growing vigorously.
If needed, you can prune as it grows but only enough to maintain the desired shape.
A hibiscus only needs to be re-potted when it becomes root bound. Re-pot either in the early spring or in the fall, right after blooming stops.
When choosing a larger pot, only go a few inches larger in diameter than the last one. Use fresh potting soil and transplant to the new pot.
If you see any brown or shrivelled roots, make sure you prune them off before placing in the new pot, although never prune off more than one-third of the root mass.
It is better to err on the careful side here.