SEED STRATIFICATION (COLD – OUTDOOR)
Many species of trees and shrubs are dormant and require a period of stratification before they germinate. In short, stratification requires cold, moist conditions, although in some cases sometimes it’s preceded by a period of warm, moist ones. The seeds are expecting to go through a winter and germinate in the spring. Without these cold conditions, some seeds will not germinate at all.
Generally speaking, there are two ways to grow tree seeds: the natural way, which often includes sowing the seeds outside in autumn, or through “assisted” germination, which is initially done indoors.
Here we’ll focus on the natural way; the way that seeds sprout into trees in nature. For “assisted” germination (indoor cold stratification) click here.
Most seeds, when sown in autumn without any pre-treatment, will begin to germinate the following spring. With autumn planting, seeds are planted outside, sometimes directly in the ground, but more often in containers, before the temperatures fall below 8° C/45° F.
Note: you can cold stratify seeds outdoor in 1. buckets, pots or boxes 2. seedbeds or nursery beds or 3. by direct seeding them on the site. The instruction below showcase the cold stratification using a bucket/pot/box size container. If you’re dealing with larger seeds such as chestnuts, oaks, walnuts plant your seeds as recommended in STEP 3 in a nursery bed.
What you’ll need?
1. Seeds – acquire them by harvesting or buying from a reputable supplier
2. (5 Gallon) Bucket/Pot/Box
3. Potting soil
- Peat moss/coconut coir
4. Wire netting
From the vault – working docs:
- Growing Chestnuts From Seed
- How to Grow Elderberry Trees from Seed
- Nitrogen Fixing Seed Propagation – Balkep
- Seed Germination Theory and Practice by Dr. Norman C. Deno