To initiate the vibrant red (or other coloured) bracts that poinsettias are known for, you need to begin a dark treatment about 8-10 weeks before you want the plant to display its holiday colours. Typically, this process starts in early to mid-October for blooming by December. 

Dark Treatment Process: Place the poinsettia in complete darkness for about 14 hours each night, from evening to morning (e.g., 5 PM to 7 AM). During the day, return it to a bright spot with indirect sunlight for the remaining hours. Consistency is crucial for the plant to develop its colourful bracts.

As a Potted Plant: With proper care, a poinsettia can last several months, often staying vibrant and colourful from November through March. The key is to provide the right light, a temperature of 18-21°C, and watering conditions. 

Beyond the Holidays: While traditionally seen as a holiday plant, poinsettias can survive as perennials when cared for properly. If you continue to water, fertilise, and prune it correctly, the plant can last for years, and you may even encourage it to bloom again in subsequent years. 

Poinsettias prefer to be kept moist but not soggy. Water your poinsettia when the top inch of soil feels dry to the touch. 

Frequency: This usually translates to watering about once a week, but the frequency may vary depending on indoor humidity and temperature levels. Always ensure that excess water drains away, as poinsettias do not like sitting in water, which can cause root rot. 

Avoiding Overwatering: Make sure your pot has good drainage and remove any decorative foil wrapping that may trap water at the bottom. 

The poinsettia (Euphorbia pulcherrima) originates from Mexico and Central America. It naturally grows as a shrub or small tree in these regions and was used by the Aztecs for medicinal and decorative purposes. 

The plant was introduced to the United States in the 19th century by Joel Roberts Poinsett, the first U.S. Ambassador to Mexico, after whom the plant is named. It has since become a traditional holiday plant, especially popular in Christmas decorations due to its bright red blooms and green foliage.