Short cool days make conditions ideal for colorful poinsettias and its close relative Euphorbia leucocephala sometimes called Snow on the Mountain. Our holiday season usually begins with Halloween and extends to Easter, but it is also the time for colds, flu bugs, pneumonia, and even variants of Covid. This means we need to be a little careful of large crowds like wild parties around New Year’s Eve. Perhaps a safer endeavor would be to focus on enjoying the fresh air of our gardens!
Although it finally feels like late fall, and we have been seeing Christmas decorations in some stores even before Halloween, the Christmas holidays don’t seem real until we get our Thanksgiving meal digested. Thanksgiving has passed but the weather has been weird. This year was particularly confusing since we have had unusually warm temperatures and the poinsettias are in full bloom.
Poinsettias, especially in Kona, Ka’u and Kohala, will soon be in spectacular color. Although mainland folks think of the poinsettia as a Christmas flower, for us it blooms from November through March. So if you don’t have them in your garden, you may purchase them at our local garden centers and dress up your home for the holidays.
Purchasing potted stock from a garden center or nursery is the easiest way to establish plantings of the holiday ornamental. However, some green thumb operators scavenge the neighborhood for hardwood cuttings when fellow gardeners prune their poinsettias following the flowering season. Getting plants this way can make you feel like a turkey if you choose cuttings from disease infected plants. If you get healthy plants, you can be sure to avoid “fowl” play.
There are a number of poinsettias available. They come in traditional reds or you can enjoy color combinations indoors and in the garden if you mingle the red plantings with white and pink varieties. Since poinsettias give color from now through March, incorporating plants into the garden design will brighten things up for more than just the holiday season.
Poinsettias will grow on a wide range of soils, including sand, rocky soil and clay. In spite of the wide adaptability, the plants will present you a better show of color if you take proper care of them.
In massed beds, fertilizer application is important. An application of fertilizer in August should now be producing large colorful bracts. The plants need repeat applications of plant food in early spring, again in June and perhaps during mid-summer if there are heavy rains.
For best results, prune poinsettias back in late winter or early spring after blooming is over. Cut them back to within 12 to 18 inches of the ground.
You’ll find that a compact plant will furnish more color than a plant with few unbranched stalks. To promote a riot of colored bracts, prune the plants several times during the growing season. Nip the new growth back after it is 12 inches long, leaving four leaves on each shoot. Be sure to stop the pruning in early September, because the flowering buds are set in early October.
Poinsettias show their color according to the day length and temperature. A plant near a lighted window or a street light often refuses to flower like a neighboring plant in a nearby darker corner. Dreary skies in September and early October will shorten the days causing plants to set buds and flower before the holiday season.
You will find that temperature is a limiting factor for a good show of flowers. If the night temperatures are much above 70 degrees, bud formation will be retarded. Freak periods of hot weather during this critical time may not permit buds to form at all. The best flower development is when the night temperatures range from 60 to 68 degrees.
For plants in your garden, one problem to watch for now are mites. Dryer conditions are ideal for this pest. Spraying with a miticide will take care of the little stinkers. If you want to avoid sprays, sprinkling the leaves daily with the garden hose is helpful. This will also minimize whitefly attacks. Avoid sprinkling in the heat of the day or in early evening so that they dry off before dark.
Poinsettias may be used as cut flowers if the stems are treated to coagulate the milky sap and reduce wilting. As soon as the flowers are cut, immerse the cut ends in hot water for about a minute. Then place them in cold water. Be sure that the steaming water does not damage the bracts.
An alternate method of halting the oozing sap is to singe the cut ends of the stem over a flame for a couple of seconds and then place the stems in cold water. For best results and longer lasting beauty, cut the poinsettias about 18 hours before they are to be used in an arrangement. Store the cut “flowers” in a cool, draft-free place during the waiting stage.
If you want to experiment with this year’s potted plant, don’t toss it out when the last leaf drops. The plant will show brilliant color next Christmas season if you follow these tips. First, store the pot, plant and all, in an out of the way place. This treatment is intended to force the plant to hibernate during the cool days while the shriveling top feeds the sleeping roots. Only water the plant to keep it from getting bone dry. Avoid giving it fertilizer. Try storing the sleeping plant in the shady corner of the carport. Toward the end of February, tenderly awake the plant by cutting off the dead top. You can grow the new plant in last season’s pot, but the poinsettia will be happier if you set it in the ground where it can flex its roots better than in the confines of a pot. Make sure you plant it where it will get lots of sun and a well drained soil. If you want to learn more, consider becoming a UHCTAHR master gardener. To register contact the UH Extension office at 981-8199 at the Hilo Komohana Agriculture Complex or Ty McDonald in the Kona office at 322-4893.