The length of time your poinsettia will give you pleasure in your home is dependent on (1) the maturity of the plant, (2) when you buy it, and (3) how you treat the plant. With care, poinsettias should retain their beauty for weeks and some varieties will stay attractive for months.
• After you have made your poinsettia selection, make sure it is wrapped properly because exposure to low temperatures even for a few minutes can damage the bracts and leaves.
• Unwrap your poinsettia carefully and place in indirect light. Six hours of light daily is ideal. Keep the plant from touching cold windows.
• Keep poinsettias away from warm or cold drafts from radiators, air registers or open doors and windows.
• Ideally poinsettias require daytime temperatures of 60 to 70°F and night time temperatures around 55°F. High temperatures will shorten the plant’s life. Move the plant to a cooler room at night, if possible.
• Check the soil daily. Be sure to punch holes in foil so water can drain into a saucer. Water when soil is dry. Allow water to drain into the saucer and discard excess water. Wilted plants will tend to drop bracts sooner.
• Fertilize the poinsettia if you keep it past the holiday season. Apply a houseplant fertilizer once a month. Do not fertilize when it is in bloom.
• With good care, a poinsettia will last 6-8 weeks in your home.
Source: University of Illinois extention
