Eastern hemlocks begin to reproduce after they’re about 15 years old. In the middle of spring, they begin producing pollen and seed cones. The pollen cones serve as the male reproduction of the tree and the seed cones have ovules that serve as the female reproductive component. The pollen uses wind to travel to the cones of the same or another hemlock tree, where it germinates. The entire fertilization takes about 6 weeks. Throughout the summer, the cone then matures with the pollen inside it and reaches its maximum size in late summer. In mid-fall, the seed cones open and release the seeds.    

For the seeds to grow, they have to have very specific conditions. The ideal temperature is around 60 degrees F, and hemlock seedlings are most successful in the shade with about 70-80% vegetative cover. The soil surrounding the seedling should have vegetation decomposing to give nutrients to the young tree. A danger for the seedlings is drying out, so it’s very important that they are in a moist environment. Once the seedling is established, the eastern hemlock grows very slowly; at most only 1.5 inches annually! After the first year, though, the roots are more established and it begins to grow at a faster rate.