How to Unlock Native Wildflower Seeds with Cold Stratification

Would cold stratification increase your success rate with seeds? In this short video lesson, you’ll learn what it is and which types of seeds benefit from a big chill.

Cold stratification is a period of cold, moist conditions that breaks dormancy for many seeds from temperate regions. Many wildflowers and trees will “wait” until they’ve had a period of stratification before they germinate. 

You can sow seeds directly outdoors in late fall and let nature stratify your seeds. Or you can mimic these conditions in your fridge.

Step-by-Step

1. Decide on the medium you’ll use – coffee filter/paper towel, sand, or vermiculite – and gather materials and a container.
2. Rinse your seed. (Check the seed instructions as some may recommend a 24 hour pre-soak.)
3. Dampen your stratification medium and squeeze out any excess water. It should be moist but not dripping wet.
4. Mix in seed into sand/vermiculite or arrange in a single layer on coffee filter. (It worked well to line a sieve with the coffee filter and then pour the water seeds had been soaking in through it.)
5. Put into a container or bag and label. The seed packet may recommend the length of time, or check Prairie Moon’s website (link below). For milkweed, we’re going to go 4+ weeks. I like to label with the “ready to plant” date, and I added a reminder in my calendar as well.
6. Check the containers each week. Let some fresh air in, add water, and re-rinse if any mold has formed. (A little mold probably won’t impact germination rates, but best to get it rinsed off.)
7. Plant your seeds into pots. Or you can direct sow most seeds around or after last frost. Check your seed packet for the depth. Most seeds should be planted 1-3x as deep as they are wide. Small seeds can be pressed into the surface of the soil and covered with burlap so they don’t dry out.

Resources shared in this video

• Sow True Seed: The Great Milkweed Germination Test
• The Mind-Blowing Miracle of Butterflies with Farmer Kim Bailey
• Prairie Moon – native wildflower seed source

This lesson was originally shared during our weekly Gardeners’ Meetup inside our gardening community. We gather most Thursdays at 8pm Eastern. Each week, I share a short, actionable lesson and we chat about gardening. We celebrate wins, learn from each other, and help troubleshoot challenges that arise.

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Now, it your turn…

Have you tried cold stratification? Tell us about your experience in the comments below!