Stratification of Seeds...Tricking Seeds

Stratification is simply tricking seeds into growing/germinating, in simple terms. It is creating an artificial winter and than creating an artificial spring. Some seeds need to be cold for a few weeks to months before they will germinate. A way to mimic winter is to put seeds into the fridge and than growing them under grow lights before moving them outside.

"The seeds of many native plants have built-in dormancy mechanisms that protect them from germinating before killing frosts or in times of drought. In the wild, seeds will lie dormant until the proper conditions for growth occur. But in cultivation, the successful gardener must become familiar with several simple pre-sowing seed treatment methods which will unlock the dormancy mechanism and stimulate quicker, more consistent germination". Source

What seeds need stratification? I do a cold treatment for all my perennials that I start from seed. I can't find a solid concrete list of what needs cold treatment so if it's a perennial it gets cold treatment. My list includes: pansies, violas, lavender, echinacea, Chinese Lantern, milkweed, lamb ears, hyssop, scabiosa, and verbena.

I'm quite lazy and like to do things simply. Seeds that need cold treatment get stuck in a zip lock bag and put into my freezer. Now that is not the correct way, but I've had success doing it. Doing research for this article has taught me I've been doing it really really wrong. So what is the correct way?

• Fill up a container (what ever you use to start seeds) with potting soil.

• Soak containers until they are wet.

• Sprinkle seeds on top and cover with soil (though some seeds do need light to germinate).

• Put container into a zip lock bag and label with variety and date.

• Put into the fridge for the recommended time.

• Once seeds have been in the fridge the recommended time put them under grow lights.

Another method is:

• Wet paper towels, wet, but not dripping wet.

• Sprinkle seeds on top.

• Fold up towels and place in a zip lock bag.

• Label with variety and date.

• Put into fridge.

• Once they come out of the fridge plant in containers and put under grow lights.

How long do seeds need to be in the fridge for? It all depends on what kind of seeds they are. Generally speaking it is anywhere from 3-8 weeks. Seed packets or the internet will have information on how long they need to stay cold. Once the seeds have had their cold treatment they are planted and cared for just like regular seeds.

Below is how I'm cold treating milkweed seeds. I collected seed pods from the edge of my pumpkin patch.. I broke open the seed pods and sprinkled them onto a wet paper towel. Folded the paper towel and put into a zip lock bag with the date and kind of seed. Every week I will check the seeds to make sure they are staying moist and there's no mold growing. Cold treatment should take 3-6 weeks and than under the lights they will go.