Know Your Nursery: Winter seed treatment
While our potted trees are happily dormant under their blanket of mulch, the Heritage Nursery staff is busy indoors preparing our seeds for spring. Most native woody seeds possess a dormancy which, until broken, prevents seeds from germinating. This built-in insurance policy protects seeds from germinating in the fall, even under conditions that might be considered favorable. In nature, dormancy is broken after a seed spends several cold winter months laying on the moist forest floor. After enough time in these conditions, the seed’s embryo is signaled that spring has arrived and it is time to emerge. This process is called stratification.
In nature, seed dormancy is regulated by the changing seasons of our climate; however, we can also control this process artificially. To stratify the seeds we collected in the fall, we store them at 31–41ºF in sealed plastic bags of moist vermiculate, sand, or peat moss for several months. When the stratification period ends, our seeds will be ready for planting just as temperatures begin to rise in the spring.
Breaking dormancy is a complex and delicate biological process in both seeds and established plants. If sufficient moisture, temperature, oxygen, light, and even hormonal levels are not right, a seed will not germinate — making it one of nature’s most impressive feats…one we all look forward to each spring!