To prune a poinsettia, cut the plant back to 6 to 8 inches above the ground in the spring, then during the summer, pinch off new shoots when they’re about 6 inches long to encourage branching. Make sure the plant gets enough sun, and water and fertilize regularly.Continue Reading
If your poinsettia still has its winter flowers, wait until it has bloomed out and is in its resting state to repot and prune. Do not fertilize the plant while it’s blooming.
Because your poinsettia has grown while in bloom, re-pot and fertilize it. Take this opportunity to prune the poinsettia down to 6 to 8 inches. To encourage rapid re-growth, keep the plant in a sunny location and watered, fertilizing about once a month.
The poinsettia should be growing rapidly by May. Now the plant can be potted again or transplanted. Bright sun and watering are necessary for the plant to grow new branches. To keep the plant bushy, pinch off the tips of new shoots when they grow to 6 inches. This combined with fertilizing every 2 to 3 weeks insures hardy branching and full foliage.
To prepare the poinsettia for its winter blooms, don’t pinch off any new growth after September 1, as the red brachts form only at the ends of branches as the days grow shorter. Continue your summer pattern of water and fertilizer. To grow the best blooms, make sure the plant gets bright sun and at least 14 hours of darkness every day from October through December.