Water is still the best preservative for Christmas trees. Make sure trees have a 1-inch fresh cut. ALWAYS keep the Christmas tree stand basin filled with water. Norway Spruce especially requires water. Its needle retention is not as good as the pines and firs.
Live Christmas trees are usually ball-and-burlapped specimens; common trees are scotch pine, white pine, blue spruce and Douglas fir. They should NOT be brought indoors for more than three days and then only if room temperatures are kept on the cool side. A hole to plant the tree should be dug as soon as possible before the ground freezes. The soil should be kept from freezing, either covering it with mulch or moving it into a warm location, such as a heated garage. Keep trees cool and dormant until ready to use. If possible, tag trees at the nursery or garden center early, but pick up or have delivered a day or two before Christmas. Indoors, keep trees cool and away from heat sources such as fireplaces and registers. Make sure to use only cool lights; any type of warmth may force the tree out of dormancy which means severe winter injury when transplanted outside. As soon as Christmas is over, move the tree to an unheated garage or building to acclimatize it to outside temperature, then plant the tree outside. Backfill with soil and warm water. Mulch the soil thoroughly with a foot of mulch to prevent the soil from freezing quickly. The warm soil will induce root development and establishment. Do not use fertilizer.