Seed Stratification

Last spring I started some Agastache mexicana seeds indoors but got very spotty germination.  I decided to investigate whether or not stratification would improve germination.  I think that it will.  Here’s the why and how:

Many seeds have built in germination inhibitors.  This prevents them from germinating until more ideal growing conditions are present.  Stratification is one method of mimicking natural conditions that seeds are exposed to prior to germination to “trick” them into germinating.  Since Agastache mexicana, also known as Mexican Hyssop or Lemon Hyssop, comes from the cooler highlands of Mexico I’m using a cool, moist stratification process similar to that used for prairie plants like Echinacea.

Some seeds can be put into a moist medium like peat or sand, put into a sealed plastic bag and put into the refrigerator for anywhere from a couple of weeks to a few months. The idea is to match the conditions of a cold, wet spring that the seeds would go through prior to germination.  Since the Agastache seeds are tiny and would easily get lost in the medium, I decided to broadcast them directly into a couple of small pots.  I then pressed the seeds gently into the moist sowing mix.  The pots themselves are sealed in a plastic bag, labeled and dated and put into the fridge.

Agastache seeds ready for stratification

Can you see the Agastache seeds? Me neither.

I will take these pots out in early January and put them under my grow lights.  Assuming that I have good germination success I’ll prick the seedlings out and transplant them into larger containers once the plants show their first set of true leaves.  The timing should work out for a mid-Spring outdoor planting in Austin.

Agastache seeds in sealed plastic bag with name and date.

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2 Responses to “Seed Stratification”

  1. Great suggestions. I have had this same scenario with several plants. The best example was Brazilian vervain. I followed all the directions and got poor results. In Colorado, I can just put the seeds in the moist home outside in the shade and let mother nature do her thing. Wouldn’t you know it, I got 2 seeds to germinate and Mother Nature got the other 100!

  2. Geoff says:


    Thanks for the comment. I’ll a germination update in January. I’ve had really good results with Echinacea in the past, but have never stratified Agastache.