I have 2 small sized Poinsettia plant from last year that still have some res leaves, they have many green leaves and also a few leaves on each plant that are a mix red/green. How do I get these plants to turn red again for the upcoming season. I have read many opinions but would love to hear the correct way from a professional. Please give detailed information, such as how often it should be watered while trying to get this process complete.
The red leaves are bracts, specialized leaves that are associated with flowers. The red bracts develop when the plant flowers, so to turn the plant red again you put the plant through a process that encourages it to flower.
To encourage flowering, bring the plants inside early in fall if they are outdoors. For a period of about 10 weeks before the holidays, place the plant in bright indoor light from 8 am to 5 pm, then place it in the dark from 5 pm to 8 am. The most important thing is to keep the plant in complete darkness through the night, to mimic the light conditions in its natural environment in Mexico. The plant uses the long dark nights to determine that it is the correct season to trigger flowering. Even a small amount of light can confuse the plant and reduce flowering. You can use a box with an opaque cloth over, or a box inside a closet, or other arrangements to achieve this. Maintain a temperature between 55 and 70 degrees F during this time. Also, keep the soil evenly moist, but not soggy. Check the soil every few days to see that it doesn't get too dry or too soggy.
Once you see that the red leaves and flowers are fully grown, the light treatment is no longer needed.