If you prune your plants after that then you may remove all the potential flowers. Poinsettia blooms are stimulated by long nights. During the period from early October through mid-November, plants should have fourteen to sixteen hours of total darkness each day. Even light from a window, street light, or headlights from passing cars is sufficient to interfere with the blooming process. This does not mean that poinsettias are kept in the dark for twenty-four hours.
Some people make that mistake and end up with dead plants.
If you cover an outside plant to protect it from light, remove the cover by mid-morning. Caladiums can be used to brighten shady areas in the landscape. Their colorful leaves are produced from spring through fall. Tubers or full sized plants in containers are available at most local nurseries and garden centers. When lawns start to turn light green it may not be diseased or even need a nitrogen fertilizer.