Dorothy is a master gardener, former newspaper reporter, and the author of several books. Michael is a landscape and nature photographer.
A Critically Endangered Beauty
It's hard to believe that a plant that produces such a gorgeous hibiscus-like flower could be critically endangered, but that is the case of the Abutilon menziesii plant (Ko‘oloa‘ula), endemic in Hawaii with declining numbers. Currently, there are only about 500 of these plants scattered across the islands of Hawaii.
The flowers bloom sporadically all through the year and in a range of colors, such as pink and white, solid pink, pale red, wine, maroon, salmon, and pale yellow. The staminal column is a yellowish color. As long as the seed pods and the flowers are picked, the flowering will continue. Flowering may slow down or even stop during the hottest parts of the year although generally, flowers are seen throughout most of the year.
The leaves, which range from an inch in width to about five inches, vary in their shapes. They have a velvety feel to them. Sometimes the large leaves make it hard to spot the gorgeous flowers that are also growing on this shrub.
Hawaii's residents use these shrubs in their landscapes in containers and as specimen plants. They are also a great accent plant and can be used in both screens and hedges.
How to Gather Seeds
Only gather mature fruits when they are completely dry (they will be a light brown color, as pictured below). Each of the fruits you collect will likely hold from one to three seeds in each chamber which can simply be shaken out (you might have to use some tweezers). Discard any seeds that have obvious holes, as they have probably been damaged by seed borers or some type of fungus. If the seeds collapse when you squeeze them with two fingers, they are not viable.
Hot water scarification is recommended for these perennial seeds and it is an easy process. Place your seeds in a pot of hot water that is almost boiling, then allow the seeds to soak in the water until it cools to room temperature. Remove the seeds and sow them immediately as scarified seeds do not store well. Viable seeds will usually sink, so if you have seeds that are floating you need to discard them.
Learn to Care for Your Plant
If you are one of the Hawaiian residents fortunate enough to have one of these critically-endangered plants growing on your land or around your home, you should know how to properly care for it. You will need to use a balanced, slow-release fertilizer with secondary and trace elements about twice a year. While an occasional foliar feeding is beneficial, monitor the frequency and amounts of applications. If you overfertilize the plant, you can cause large, limp foliage and your plant will produce fewer flowers.
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Note: Secondary elements include calcium, magnesium, and sulfur. Trace elements include boron, iron, copper, chlorine, manganese, molybdenum, and zinc.
For a healthy shrub and a high flower count, the Abutilon menziesii (Ko‘oloa‘ula) plant should be planted in full sun (partial sun at the very least). Plants need to be spaced about four to six feet apart if you are trying to showcase individual shrubs. If you are planting them for use as a hedge, spacing should be tighter (usually from two to five feet apart).
You should water the ground beneath the shrub to avoid an excessive amount of water on the foliage and branches which may lead to various fungal problems. Also, it is important to allow the soil to dry between waterings. Once your plant is established you will have little reason to provide it with additional water except in periods of extreme drought.
You can prune the shrub to any height you wish as it is a matter of taste, but avoid cutting the branches too far back to the major stem because they may not grow new branches. Make sure you sterilize your tools before you start using them to prevent the spread of disease.
Remove any plant parts that are damaged, as well as other damaged or dead shoots, and remove the branches just above a stem junction. You should never prune this plant by removing more than a third of a stem, in order to leave the plant with enough resources to continue flowering and remain a healthy plant. You can remove bare or aging stems by cutting them at the base of the plant if it appears to be too dense.
Pests and Diseases That Ruin Plants and Flower
Some of the pests capable of destroying these critically endangered plants are Chinese rose beetles, aphids, and mealybugs. The beetles will usually leave unsightly holes in the leaves of the plant, but the aphids and mealybugs can be a problem around flower buds.
Overwatering, along with periods of continuous, heavy rainfall can cause black sooty mold to form on the shrub.
© 2018 Mike and Dorothy McKenney