The smell of a Christmas tree is primarily due to the chemicals released by the tree's needles, such as terpenes and other essential oils. Without these chemicals, a Christmas tree may not have a strong odor or smell like a traditional Christmas tree. However, adding scented ornaments, garlands, or other decorations can help create a festive scent. Additionally, regularly watering your Christmas tree can help it retain its natural scent. Finally, consider using a spray-on fragrance or placing potpourri near the tree for added scent.