Poinsettias are popular ornamental plants native to Mexico where they are known as "la flor del nochebuena", or "the Christmas Eve flower". They are known for their bright red and green foliage, which makes them a popular choice for holiday decorations. However, some people may notice that the leaves on their poinsettias do not turn red, but instead remain green. There are several reasons why poinsettia leaves may not turn red:
1. Lack of Light
Poinsettias require a certain amount of light each day to trigger the production of red pigments in their leaves. Without enough light, the leaves may stay green. If your poinsettia is kept in a low-light area or is not given enough exposure to natural sunlight, the leaves may not turn red. To ensure that your poinsettia receives enough light, place it near a south-facing window or under artificial light for at least six hours each day.
2. Temperature Fluctuations
Poinsettias are sensitive to temperature changes, especially those that occur suddenly. Fluctuations in temperature can cause the leaves to turn yellow or fall off, which can prevent the plant from producing red pigments. To avoid temperature fluctuations, keep your poinsettia in a room with a stable temperature between 60 and 70 degrees Fahrenheit.
3. Watering
Over or under watering can also affect the color of a poinsettia's leaves. If the plant is not given enough water, its leaves will begin to wilt and turn yellow. This can prevent the plant from producing red pigments. However, if you overwater the plant, the roots may become waterlogged, causing the leaves to turn yellow and fall off. To prevent issues with watering, water your poinsettia only when the soil feels dry to the touch and make sure the pot has good drainage.
4. Ethylene Gas Exposure
Poinsettias are sensitive to ethylene gas, which is naturally produced by many fruits and vegetables, and is also used in the ripening process of certain produce. Exposure to ethylene gas can cause the leaves on a poinsettia to turn yellow or drop off, preventing the production of red pigments. To avoid exposure to ethylene gas, keep your poinsettia away from ripening fruit and vegetables, and do not place it near gas stoves or heaters.
In conclusion, there are several reasons why the leaves on a poinsettia may not turn red, including lack of light, temperature fluctuations, watering issues, and exposure to ethylene gas. By providing your poinsettia with the right amount of light, water, and temperature, and keeping it away from sources of ethylene gas, you can encourage the production of red pigments and enjoy the bright colors of this festive plant.