Grow poinsettias in areas protected from cold drafts and extreme temperature changes that receive at least six hours of indirect sunlight a day. Water plants when the soil begins to feel dry, and ensure pots are able to drain properly. Water plants throughout the winter, and reduce the volume and frequency of waterings during the summer once the plant has finished blooming.
In April or March, prune plants by approximately 8 inches between, and begin adding fertilizer to the soil at monthly intervals. Re-pot plants in early June, using new pots that are no more than 4 inches wider than the originals. Use potting mix that is high in organic matter. Indoor plants may be transplanted to a garden or other outdoor location in warmer climates where frost is not an issue. Select outdoor planting sites that offer high-quality soil, good drainage and abundant sunlight.
Water outdoor plants at regular intervals, keeping soil moist but not too soggy. Add fertilizer more often, increasing the frequency to every few weeks, and prune plants at regular intervals by removing the growing tips from new shoots that have reached 4 to 5 inches in length. When fully grown, poinsettias can reach heights of up to 16 feet.