By Dan Marzu
UW-Extension Agriculture Educator
Well the simple answer would be to throw it out or preferably compost the plant. We generally treat poinsettias as an annual plant that brings joy to everyone for a short period of time during the holidays. In their native southern Mexico environment they are actually a perennial shrub that will grow 10 to 15 feet tall. If you have a little bit of a green thumb, you can keep the poinsettia throughout the year to enjoy its green foliage and eventually the brilliant colors during the holiday season.
Many of us think of the red, white, pink, marbled, and even speckled parts of the poinsettia as the flower petals. However, these are modified leaves called bracts. The flower is in the center of these bracts. They will have a yellow color to them especially while pollinating. Once the plant is finished pollinating or when you can no longer see the yellow pollen on the flowers and the bracts begin to turn a muddy green and fall off it is time to prune the plant. This will usually take place at the end of April. Cut the branches of the poinsettia back to eight inches from the soil line. This won’t be the prettiest stage of the process as what will be left will be bare, cut wood stems and branches. Don’t panic as in a couple weeks after pruning you will be able to see new growth on the stems and branches. Dispose of the pruned branches. Contrary to belief the leaves of the poinsettia are not poisonous. In a study by The Ohio State University, a 50 pound child would have to eat 500 to 600 leaves to have any side effects which are commonly upset stomach and vomiting. It is always best practices to keep the cuttings away from young children and pets to prevent any accidental consumption of the plants. If the poinsettia is not patented you may propagate the cuttings. Contact the UW-Extension office for more information on patented plants and propagation techniques.
During this time be sure to place the poinsettia near a non-drafty, sunny window. Keep the soil moist, allowing for water to flow freely out the bottom of the pot. Do not allow the pot to sit in water as it might damage the plant by causing root rot. Fertilize the poinsettia after pruning using a balanced fertilizer such as 10-10-10 at a half rate. Continue fertilizing every three to four weeks throughout the spring, summer, and fall months.
Once night time temperature are consistently 55° F, the poinsettia may be placed outside in partial shade. Monitor the watering needs; as the plant grows, it may need more frequent watering. Also, look for insect pests such as white flies, mealy bugs, soft scales, and spider mites. There are several organic and non-organic insecticides available to use to control these pests. Contact the UW-Extension office for insect pest management options if they occur. As with any pesticides, always read and follow labeled directions.
During the summer months, the poinsettia may need to be transplanted into a larger pot. Select a pot that is two to four inches larger than the original pot. Use a soil mix that is high in organic matter such as peat moss. The poinsettia may also need to be pruned back to control the height and promote side branching. On each branch pinch off about an inch leaving four or five leaves per stem. A milky white sap may be secreted. If you have a latex allergy be sure to protect yourself as the sap may cause a skin reaction. Pruning may need to occur once more during late summer following the same procedure.
As the temperatures begin to drop to 55° F, bring the poinsettia indoors to a sunny window. In the beginning of October, begin the process to force the bracts to change color. This is accomplished through keeping the poinsettia in complete darkness for 14 hours each night either by moving into a dark room or placing a box over the top of the plant. Any stray light from street lights, passing vehicles, or house lights will delay the flower buds from setting, preventing the bracts from changing color. The temperature in the room should be between 60° F and 70° F. Similar to the poinsettia’s reaction to light, if the temperature is too low or too high the flowers will not set, delaying the color change. This process will take about eight to 10 weeks for the bracts to fully change color.
Although this process seems a little intimidating, with a little bit of patience and persistence you will be able to keep the poinsettia to enjoy for many years to come. For all your horticulture and agriculture questions please contact Dan Marzu, Extension Agriculture Educator, at 715-539-1078 in Merrill or 715-627-6236 in Antigo or by email at Daniel.firstname.lastname@example.org.
May 2018 provide you and your loved ones a bountiful harvest of new experiences and memories.