What is Stratification?
Answered by: Richters Staff
Question from: Mike
Posted: Before April 1998

I recently received the 1997 Richters herb catalogue and I must say that it looks great! Congratulations on the great job!

I noticed that on Page 6 under Abbreviations Used: Sow-Numbers, ‘S’ stands for "stratification required". Can you please tell me what this means and how I would go about doing it?

‘Stratification’ is a term for a nursery practice designed to break seed dormancy. It is most applicable to tree and shrub seeds but it can also be used for alpine and wildflowers seeds, including many herbs.

Many plants produce dormant seeds. It is nature’s way of preventing germination at an inopportune time. For example, seeds maturing in the fall stand a better chance surviving if they germinate in the spring and not in the fall. To prevent early germination, many plant species produce seeds with hard seed coats, immature embryos or containing germination inhibitors. Typically, the seeds of these species need a moist cold treatment for a period 1-24 months or longer. During this treatment the seed coats will soften, or embryos will mature or inhibitors will leach out of the seeds depending on the dormancy mechanism.

The standard practice is to store seeds in stratification boxes. A layer of moist sand is placed at the bottom. Then the box is filled with layers of seeds alternating with layers of sand culminating in a thick layer of sand. It is easy to see where the term ‘stratification’ came from. The whole mass is kept moist but not soaking wet, at a temperature of 5 degrees Celsius (40 degrees Fahrenheit).

The seeds remain in the boxes until there is evidence of swelling and bursting. Before the germination process proceeds too far, the seeds are removed and sown in seedboxes at room temperature.

Also, I was wondering if Richters sends information sheets that give sowing instructions and provide info concerning the uses of the herb for medicinal purposes (ie. give info on how to make the herb into a ‘remedy’ or ‘medicine’) with the shipment of purchased herbs.

We are planning to produce a series of "GrowSheets" which will contain essential facts on growing herbs from seeds. We expect to start posting some on the Richters website in 1997. It is a big project and it will be several years before we have sheets available for all herbs we sell.

In the meantime, Deni Bown’s book, Encyclopedia of Herbs & Their Uses is an excellent source of information. For many of the herbs the author has included a "Growth and Harvest" box which we find to be very useful. The book is available from Richters.

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