Some folks new to Hawaii are overwhelmed by the great variety of tropical plants available here. Fortunately, in Hawaii, everyone can have a green thumb if they have the desire.
Planning a beautiful garden to surround your home is loads of fun. Tropical gardening books and magazines help give you ideas. The Kona Outdoor Circle has a great horticultural library and, of course, you can get ideas from neighbors with attractive gardens. Once you have decided on the perfect plants to fit your needs, check out our local nurseries and garden centers. If the plants you like are not readily available, you might consider propagating your own. Some plants are not available at local nurseries, but you may see a fantastic specimen of what you want in your neighborhood. Your neighbor will likely be willing to give you some cuttings. Many plants are easily grown in this manner.
Allowing nature to grow roots on tips of plants requires the simplest of facilities. This ranges from a plastic bag containing a handful of damp sphagnum moss to a cast-off wood box containing a 2-inch layer of gravel topped off with a 4-inch layer of perlite or a mixture of peat and perlite.
To gain confidence in the rooting technique, try using a 1-gallon can. It will make a dependable propagating unit. Remove the top and wash out any residue. Punch a ring of six or eight holes in the side halfway between the top and bottom. Fill the can with gravel or coarse cinder to within 1 inch of the holes. Cover the gravel with a 1-inch layer of sphagnum moss and then fill the remainder of the can with coarse sand.
You now have a propagating unit with its own water reservoir. Water below the side holes in the can moves up from the bottom of the can by capillary action, keeping the sand and the rooting cuttings moist. Under normal conditions, this simple unit will need watering about every two weeks.
A 1-gallon can will hold a score of cuttings. To ensure success with the first batch of cuttings, try your luck with coleus or crotons. These plants are a neophyte’s friend. They will root even with over-coddling. Edible hibiscus and the tapioca plant, or cassava, are also easily started in this way. You might try some of the more difficult plants like camellias or vireya rhododendrons.
If you want to get into the mass production of cuttings, then build a wooden box about 36-by-36-by-12 inches deep. Next, nail four legs to the box so that it will become a waist-high, no-stoop unit 3 feet square and 1 foot deep. Place the unit in semi-shade and fill with a few inches of cinder topped with about 4 inches of damp perlite or peat. Next, buy a mist head that can be attached to a water hose. Set the constant day misting device in the center of the propagating box and you are ready for rooting cuttings. In cooler parts of the island like mauka Kona and Hilo, an intermittent spray will suffice.
The best time to make cuttings is in early morning. This is the time when the largest amount of water is in the plant. Keep the moisture in the cuttings by placing them on a moist paper or cloth when removed from the plants. Do not stick the ends of the cuttings directly into water when removed from the plant. Also don’t place cuttings in any propagating medium until 15 minutes after they have been made. This will tend to discourage disease problems.
Make cuttings from 4 to 6 inches long, preferably with the cut made just below the node, and leave as many leaves as possible on the cuttings. Stick them in the propagating medium 1.5 to 2 inches deep and space so the leaves overlap about one third. Firm the medium and water.
Transplant into pots after 1-inch-long roots have developed. Be sure to get them out of the propagation bed before they are hard-looking and yellow. Keep them in pots or cans until the roots are well-developed. This may be just a few months for crotons or more than a year for some of the slower plants.
When it comes to propagating tropical fruit trees, many are propagated by seed, but the quality may not be equal to the parent plant. Mango, avocado, citrus and macadamia nut trees require grafting for best results. Another propagation method used is air layering. It is most often used in the propagation of rainbow shower trees. These are in full bloom much of the year except where they are improperly pruned. Hat racking describes this type of butchering — the tree looks more like a hat rack than a tree.
Trees that require grafting or air layering are best supplied by a local nursery or garden center. If you want to try your hand at grafting or air layering, check out “The New Sunset Western Garden Book.” There are also gardening classes frequently taught through the University of Hawaii College of Tropical Agriculture and Human Resources. Contact the nearest UH Extension office. To become a gardening expert, ask about the UH master gardening classes.
Once you get your green thumb groove on, you are considered a real kamaaina.