How to Cold Stratify Seeds Indoors

I have huge plans for my front yard this year.

Huge. Gigantic. Super-sized. 

I’m converting a sad, invasive grass filled yard into a pollinator paradise.  I cannot wait to see it full of flowers, herbs and insects.

But in order to reach that goal, I have a bit of work to do. Most of the laborious work we completed last fall (laying down newspaper, compost and woodchips to convert it to a Back To Eden style garden) but I still have quite a lot of planning and planting to achieve.

Click here to read about Back to Eden gardening and how to get started!

A lot of the flowers on my grow list include cold hardy natives like lavender, milkweed and echinacea. These seeds require a bit more preparation before I get to plant them, though. More specifically, they require a period of cold stratification.

“Cold stratif- what?!”

Simply put, cold stratification is a way of breaking a seed’s dormancy period prior to germination. It’s a technique that I like to use to simulate natural conditions as if a seed had to go through winter and then be ‘awoken’ by the damp, warming spring conditions.

There are a great number of seeds that need to go through this cold and moist period for good germination success, many of them being native perennials such as the milkweed and coneflower species I mentioned above.

Many of these seeds have built in mechanisms to prevent premature sprouting and germination on unusually warm winter and spring days. Planting them directly into a seed starting mix along with your tomatoes and herbs will likely not result in the germination rates you would hope for, so it is necessary to take a few extra steps to ensure success.

My cold stratification method requires just a few materials, ones that you more than likely already have in your home!

A refrigerator, some air-tight containers such as tupperware, and toilet paper or paper towel. You can also use resealable plastic baggies if you promise me to reuse them year after year!

Really. It’s simple.

All I do is get the paper towel/toilet paper/flour sack hand towel damp with water. We’re not going for wet here, just moist.

Sprinkle your seeds on the towel, then fold the sides over a couple of times. Stick this folded moist package inside your air tight receptacle of choice, then label it! Don’t forget this step. Trust me. Then stick them in your fridge!

Different seeds require different lengths of cold stratification, but in general you’ll be aiming for about 3 months. This year, some seeds slipped my mind until the last month before I needed to sow them, so they only got 1 month of time in the fridge with no issue.

I cannot possibly outline every possible seed scenario for you here, so do a quick google search for your seeds if the information is not on the back of the seed packet.

My Results

This has been my first year attempting to cold stratify seeds indoors prior to planting them. It has been a piece of cake. Overall, I’d say 90% of the seeds that I cold stratified have successfully germinated. Of those 10% that did not germinate, I think it had more to do with the age and quality of the seeds than the actual process of cold stratification. 

Don’t wait too much longer! Get those seeds in the fridge and let me know how it goes for you. And be sure to follow along with my wildlife habitat project this year!

Until next time,

Becca