How do you know when pine cones are ripe?

One way to test if pine cones are ripe is to drop a few test cones into a container with SAE 20 motor oil. Cones will float if they are ripe, so cones from spots on the tree near the test cones are ready for harvest.

Do pine cones start out green?

Look closely at a conifer, and you will likely see a number of green cones on the tree that have not yet ripened. Depending on the tree species, these can take anywhere from one year to several years to ripen into the brown, dry cones that are more readily apparent on the tree or on the ground around the tree.