Plant your poinsettia in an area that receives full sun most of the day. However, keep in mind that to put out flower buds, poinsettias require 14 hours of complete darkness each day for 6 to 8 weeks before flowering. Any interruption to this dark period can delay or prevent the plant from flowering. Watering & Soil. Keep the soil moderately moist at all times. Poinsettias grow best in moist, well drained, fertile soils. As long as the soil is well drained, they will grow satisfactorily in a wide range of soils, including sand, muck, marl and clay.
Conical taper is the change in the diameter of a circular solid along its length. It can be expressed in linear units such as inches per foot or as an angle. When the decrease in diameter and the length are viewed as two sides of a right triangle, trigonometry can be used to convert the linear unit expression to an angle.
Taper needles are used for tissue that is easy to penetrate, such as bowel or blood vessels. In contrast, the tip of cutting needles is triangular in shape, and the apex forms a cutting surface, which facilitates penetration of tough tissue, such as skin. Cutting needles make it much easier to penetrate tough tissue.