Acorns need a period of cold stratification to germinate, which simulates the winter conditions they would experience in their natural environment. This process helps break dormancy and prepares the acorn for sprouting when the weather becomes favorable in spring.
The specific time required for cold stratification can vary depending on the oak species and the conditions in your region. However, a common recommendation is to keep the acorns in the fridge for at least 30 to 90 days. Here's a general guide to follow:
- Collect mature and healthy acorns from the ground (avoid green or damaged ones).
- Place the acorns in a container with a mix of slightly damp peat moss, vermiculite, or sand. Ensure they are not submerged in water.
- Seal the container and store it in the refrigerator (not the freezer) at a temperature between 33°F to 41°F (1°C to 5°C).
- Check the acorns periodically to ensure they remain moist but not waterlogged.
- After the recommended cold stratification period, you can remove them from the fridge and plant them in a suitable location outdoors.
Keep in mind that acorns from different oak species might have varying germination requirements, so it's always best to research specific guidelines for the type of oak you have. Additionally, some species may not require cold stratification at all and can be planted immediately after collecting.
Remember that germination success is not guaranteed, as it depends on various factors, including the quality of the acorns, the species, and environmental conditions when planting.