külmstratifikatsiooni

Külmstratifikatsioon, also known as cold stratification, is a horticultural technique used to break seed dormancy and promote germination for certain plant species. It mimics the natural winter conditions that many seeds require to become viable. The process involves exposing seeds to a period of cold, moist conditions for a specific duration, typically ranging from a few weeks to several months.

The primary purpose of cold stratification is to overcome physiological dormancy mechanisms within the seed coat or embryo. These mechanisms prevent germination until the plant perceives that environmental conditions are favorable for survival and growth. By simulating a winter period, the cold and moisture signal to the seed that spring is approaching, triggering the necessary internal changes for germination.

To perform cold stratification, seeds are usually mixed with a moist medium, such as peat moss, vermiculite, sand, or even damp paper towels. This mixture is then placed in a breathable container, like a plastic bag or a sealed jar, and stored in a refrigerator. It is crucial to maintain consistent moisture levels throughout the stratification period, ensuring the medium remains damp but not waterlogged, which could lead to fungal growth or rot. The temperature is typically kept between 1 and 5 degrees Celsius (34 to 41 degrees Fahrenheit).

Different plant species have varying stratification requirements regarding temperature and duration. Some may need only a few weeks of cold treatment, while others might require several months. Researching the specific needs of the plant species being propagated is essential for successful cold stratification. After the required period, the seeds are removed from the cold and planted in a suitable growing medium to germinate. This method is particularly effective for seeds of temperate climate plants, including many trees, shrubs, wildflowers, and some vegetables like peas and asparagus.