Spruce tops are a great renewable resource and one of the favorite staples for holiday decorating. Cut from White and Black Spruce in northern Minnesota and Canada, it continues to grow back again year after year. The cutting of spruce tops is licensed by the state and provinces. Grown in this manner, the tree tops will have the form and foliage of more mature trees, often bearing cones at a very small size.
You may be thinking, this is all well and good, but does an evergreen, needle bearing tree ever grow a new top after it has been cut off? The is yes, but depending on the species. White pine trees will definitely grow vertically after topping. An existing branch or new shoot will turn into a new leader, and grow pretty fast. Spruce trees are known to regrow a top from a branch near the cut. They nearly always establish new leaders. Tree age is a big factor and young trees respond faster. To learn more about renewable Spruce Top harvesting watch the video by Black Spruce Holdings, LLC.
Spruce tops trace their roots back to Duluth, Minnesota, in the 1950s when they were harvested in the Black Spruce bogs of northern Minnesota and sold as individual table-top Christmas trees, although the Minnesota DNR (department of natural resources) states that this trend began in the 1930's. By 1960, over a million and a half tops were distributed across the United States and parts of Europe. Most spruce top harvest takes place on low productivity spruce stands on public lands. Harvest typically takes place during October and November on wet sites when the ground is unfrozen.
Spruce tops are usually sold in bundles of five or ten, depending on size. Fresh tree tops are used for decorating outdoors, "planted" in pots, planter boxes, or in-ground beds. As general rule, 10 inch pot will need 5-6 tree tops; a 12 inch pot will need 6-7; and a 14 inch pot should be filled with 7-9 tops, but these numbers not set in stone. Some designers suggest using 7-9 spruce top for 12” pot giving the arrangement an even fuller look. If you have larger pots, place several jumbo tops in the center of the pot to give height to the arrangement, then plant out to the edges with regular spruce tops. You can also add lots of other greens to your pots, planters, and window boxes to personalize them. Accent them with Magnolia, Winterberry, Eucalyptus, Rose Hips, Dogwood or Willow branches, and Birch poles. Look around your garden or yard for more accents from shrubs and dried seed pods. You're only limited by your imagination!
Resources: https://ask.extension.org/questions/299304