Seeds of many plant species are dormant, so they are not able to germinate immediately after harvest. For the seeds to germinate, their dormancy must be broken. For this purpose, the seeds are subjected to various treatments, such as e.g. stratification. Seewhat is seed stratification , what it is andhow to do seed stratificationat home. Here are proven ways to stratify!
Seed stratification is often done in the refrigerator
What is seed stratification?
Stratification is one of the methods of seed dormancy interruptionStratification aims to accelerate and even out seed germination. This treatment consists in treating the seeds with the appropriate temperature, maintaining high air humidity and ensuring proper gas exchange. We distinguish between cool, warm and cool-warm stratification. For amateurs, the most common method is cold stratification, i.e. keeping seeds at low temperature (0-7 ° C) for a certain period of time.Seeds oftrees, shrubs, perennials wintering in the ground and many species of potted plants are stratified. The stratification temperature and its duration are determined individually for each species (e.g. Chinese citrus for 30 days at -1 to -5 ° C, apple tree 60-90 days at 0 to 4 ° C, peach 90-120 days. at 0 to 7 ° C).
When to start seed stratification?
The stratification procedure should be startedearly enough for the end to coincide with the expected spring sowing date.Usually the seed stratification start date is February-March. However, this is not a rule and in some plant speciesthe start date of stratificationmay be earlier or later.
How to stratify seeds?
At homeseed stratification is best done in the refrigerator . We can do it in several ways:
1. Stratification of seeds in pots with substrate:
One of theways to stratify your seeds at homeis to plant them directly into pots filled with substrate in which to grow your plants. The substrate used for stratification is usually a mixture of fine sand and peat in a 1: 1 ratio. Before being placed in the refrigerator where we store food, the substrate must be sterilized. For this purpose, heat the moist substrate for 1 minute in the microwave or roast it in the oven at 100 ° C for 30 minutes.Afterhas cooled down, the substrate can be stratified in the refrigeratorBefore sowing the seeds, water the substrate with water - it should be moist, but not sprayed. The height of the substrate layer in the pot should be at least 5 cm. Cover the sown seeds with a thin layer of substrate and sprinkle it with water. Then we put the pots in string bags. We use a pin to make holes in the bags to allow air to circulate. Before closing the bags, sprinkle them with water. Place the closed pouches with pots in the refrigerator.
2. Stratification of seeds in a bag with a substrate:
Anotherway to stratify seeds isby mixing them with moist, previously sterilized soil (in a ratio of 1: 3 or 1: 4). Pour soil and seeds into a breakfast bag. Then shake the closed bag vigorously several times so that the seeds and soil mix well. Put the tied bag in the fridge. Occasionally the bag should be untied and lightly shaken to ensure air exchange and even moisture in all layers of the earth.
3. Seed stratification on a paper towel or cotton pad:
Instead of pots and bags with soilfor seed stratification, we can use paper towels and cotton padsThey are definitely more sterile than sand-peat substrate. Fold a few sheets of paper towel into an accordion and soak it with water. Sprinkle the seeds on a wet towel. Then fold the layers of the towel in half and place them in a string bag in the refrigerator. We do the same with a cotton swab. Spread the seeds on a swab soaked in water, then fold the swab in half and close it in a string bag, which you put in the fridge.
Before placing the seeds in the refrigerator, it is worth describing them in advance with the name of the species and the date they were placed in the refrigerator. Throughout thestratification periodwe control the substrate humidity - it must be constantly moist.
When to end seed stratification?
The seed stratification period lasts from a few to several weeks.The signal for the end of stratification is the appearance of the first germinating seeds.This means that the dormancy of the seeds has been interrupted and they are ready for sowing. The stratification time should not be extended, as it negatively affects the later development of seedlings (e.g. badly formed root necks). The seeds ready for sowing are gently transferred to the pots (except for seeds already stratified in pots), in which we will produce seedlings using a toothpick or a needle.
MSc Eng. Agnieszka Lach
Based on: A. Faktczyk, Nursery orchards, PWRiL, Warsaw 1998, pp. 87-89; Collective work edited by W. Wesoły and M. Hauke, Forest Nursery from A to Z, Information Center of State Forests, Warsaw 2009, pp. 224-228
