San Franciscos is another common name sometimes used for the crotons. Euphorbia pulcherrima . It is an excellent house plant and one that can be grown on and brought into flower year after year. In nature most poinsettias become large shrubs. If they are to be maintained in containers either choose a large container or practice pruning to keep the plants in bounds.
Poinsettias require short days, long nights to trigger flowering.
If protected from lights that would cause long days, short nights, most will come into color in time for Christmas. To get color earlier they should be covered a few hours each day to shorten the length of day. Other members of the genus Euphorbia are common as house plants. Euphorbia splendens is the crown of thorns , a small, shrubby plant with heavy development of thorns. It has clusters of small flowers which are especially interesting when they appear in the heavy thorny growth.