Start with clean glass jars. Add a layer of fresh spruce tips, then cover them with sugar (or your preferred alternative). Press everything down firmly with a spoon before adding the next layer. Keep repeating until the jar is filled to the top, packing it as snugly as you can so very little air remains inside.
Once the jars are set in the sun, the sugar will slowly dissolve and pull moisture from the spruce tips. As this happens, the contents will sink down - this is expected and nothing to worry about. Close the jars tightly with lids.
Place the jars in a bright, sunny spot where they’ll get plenty of light throughout the day. Anywhere around the house works, as long as the sun reaches them. Leave the jars there for about 40 days.
As the sugar liquefies, gently turn the jars upside down every two to three days. This helps keep the spruce tips fully submerged in the syrup as it forms.
After 40 days, open the jars and strain the syrup. A fine sieve works, but clean gauze gives the best result. Let the syrup drip through slowly, then discard or compost the softened spruce tips.
Transfer the finished syrup into clean bottles or smaller jars. Store it somewhere cool and dark. The syrup is thick enough that refrigeration isn’t necessary.