The white ones and the pink ones and the polka-dotted poinsettias are acquiring new fans each year, but more than 90 percent of plants sold still have red flowers. Technically, all poinsettias have yellow flowers - that wimpy little thing in the middle of the colored bracts.
A bract is a modified leaf growing just below the flower, and in most cases is inconspicuous. Poinsettias and bougainvilleas with their brightly colored bracts are among the few exceptions.
All of this was explained by Ed Mersino, a county agent with the Cooperative Extension Service of the University of Hawaii. The extension service is sponsoring a demonstration tomorrow on the science of shopping for poinsettias.
The first thing to decide upon is the color, and at Christmas most of us traditional types opt for the red plants with the green leaves.
"There are a lot of whites and pinks out there," Mersino said. "For Christmas there's Jingle Bells," a kind of dotted pink, red and white. "You can also occasionally find Lemon Drop, with yellow bracts, but it isn't grown much here any more. It doesn't color well in our climate, and seems to need colder weather."
Plants with colors other than red were bred to appeal to growers as a year-round plant, for nonseasonal sales. But it was an idea that never took off, like selling Easter lilies at Thanksgiving.
But there's a market for the other shades, among people who are trying to match colors in decorating. "The Royal Hawaiian Hotel, for example, ordered pink poinsettias to go with their pink hotel," Mersino said.
When choosing a plant, regardless of the color, look for one that is evenly formed, symmetrical, with no broken branches. The flowers grow on stiff, upright canes that are brittle and break easily. Remember this when taking your plant home. Brace it in your car because if it falls over, the canes may snap and they won't grow back in time to flower for Christmas.
Look for a plant that is free of disease, recognized by spots on the leaves. "This year's crop should be free of whiteflies," Mersino said, referring to the scourge of the poinsettia growers.
Poinsettias are particularly prone to these pests, but growers this year have used Marathon, an insecticide in granule form. "It is very expensive, $100 a pound, but an average pot requires only 1/4 teaspoon and only one application," Mersino said.
"The plant takes it up within a week, and retains it. Marathon is much safer than spraying, safer for the grower to handle and safer because it doesn't drift."
The only other pest is the mite, but you'll have to take in on faith that your plant is mite free. You can't see mites without a microscope, and you will look funny at the garden shop carrying one.
Finally, examine the bracts themselves, particularly if you are buying plants now. Look for bracts just beginning to open if you want mature blossoms at Christmas.
At home, keep the plant away from drafts and heat. Don't put it on top of the TV or at a sunny window. Poinsettias do best in a room with enough natural light to read a newspaper by day.
Water it every week or so to keep the soil damp but not soggy. "If you give the plant light and water, it will last through February," Mersino said.
Then what? Mersino votes for the compost pile rather than trying to plant it. "Most poinsettias are bred for growing in pots, and for a short life.
"They aren't growing in soil, but in perlite or peat. The older varieties you see growing in local gardens were adapted to grow in soil, but these new ones aren't. A lot of pathogens (disease-causing micro-organisms) in the ground will attack the roots," he said.
"You need well-drained soil and whitefly control, and the plant must be away from the light. Once it flowers, it doesn't matter how much light it gets - you can leave it in a room with 24-hour light, but in the period before the flower buds are initiated you need a longer period of dark than daylight."
Flowers won't appear if the plant is located near a street light, unless, Mersino says, the plants are covered each night with a box.
Despite last month's heavy rains, prices for poinsettias are about the same as last year. "The growers had some damage, but there are still a lot of plants available," Mersino said. "And poinsettias are not poisonous. If a child or a pet eats a leaf, it won't make him sick. I wouldn't make a salad of poinsettia leaves, but nibbling on one won't kill anybody."
The garden, operated by the Cooperative Extension Service, will be open to the public from 9 a.m. until noon. For information, call 453-6050.