Your seed packets have arrived in the mail, you’re skimming the growing instructions on the packets and you come across a note along these lines: “This seed needs to be cold stratified for 30 days before planting.” Strata-what? What’s this new step? If you’ve primarily been growing an annual summer vegetable garden you may not have come across cold stratifying before. But if you’re branching out this year, don’t let cold stratification scare you off! It’s not complicated and easy enough for even beginner gardeners.
Despite being a 50-cent word, cold stratification for seed couldn’t be simpler and I bet you already have everything you need to complete this project on hand already. In the past I’ve had some seeds that just refused to germinate, specifically lavender and some herbs. I had seen the word “stratification” but had no idea what it meant and just never bothered to look it up. I’d been planting beans, kale, and other veggies with no problem. Certainly the same methods would work on these new seeds…nope! I wasn’t just unlucky, I was skipping a critical step to ensure germination. Read on to make sure you don’t make the same mistake!
Note: This post contains affiliate links. We earn a small commission at no additional cost to you. Read our disclaimer for more details.
What is cold stratification?
Cold stratification is essentially mimicking what seeds would experience out in nature during the winter. Two main ingredients to winter – cold and wet. Whether rain, snow, or ice, seeds would be moist a significant part of the time. And winter, of course, has cooler weather. For example, if a flower dropped its seed back in the autumn, it wouldn’t want its seed to sprout too early and then die on a frosty day. So these plants adapted to have tougher seed coatings that keep their seeds dormant during the winter months.
While you could technically sow these seeds like you do all your summer vegetables, success would be marginal and haphazard. Stratifying your seed will allow them to germinate more quickly and grow more readily. Both wins for the gardener! Some seeds really do need us to act like mother nature before sprouting. So how do we humans mimic nature? We simply keep the seeds damp and cool for several weeks to wake up the seeds from dormancy.
What seeds need cold stratification?
Typically seeds of perennials will need to go through cold stratification. For example, a perennial vegetable like asparagus will germinate better if its seed is kept cold and moist for a few weeks. Plus many herbs, flowers, and medicinals require a stratification period for best germination. Things like echinacea, yarrow, black-eyed susans, arnica, rosemary, and lavender.
Most seed packets will list how many days a particular variety needs to be kept cool. Generally most of them will be between 4 to 6 weeks. If your seed packet doesn’t provide instructions, a quick google search will clarify that in jiffy.
Items needed for stratification
The great news for beginner gardeners is that cold stratification doesn’t require any special tools or equipment. You should have everything on hand already for this easy project to jumpstart your garden this year. You will need:
See, I told you that you already had these things in your house!
How to cold stratify seeds
Label your baggies
Unless you enjoy the thrill of growing loads of mystery plants, label those ziploc bags! We’ve grown enough mystery pepper plants that later burned our lips off that we’ve come to value the humble label on all our seedlings.
Moisten paper towels with water
Get the paper towel moist, but not sopping wet. Remember, we’re mimicking winter soil, not a puddle.
Place seeds on paper towel in bag
Sprinkle the seeds on half of the moist paper towel and fold over to cover the seeds. Then place the paper towel in the ziploc bag and partially seal. The bag is to help retain moisture, but not totally eliminate air.
Store in refrigerator
Stick your (labeled!) ziploc bags in the refrigerator for however many days/weeks your seed packet specified before planting them in soil. We like to place our handful of bags in a tupperware to make storage a bit more efficient.
That’s it! It really is that simple, quick, and easy to ensure successful germination of all your favorite herbs, flowers, and medicinal plants.
Happy sprouting!
