Cold Stratification of Native Plant Seeds

Many of our Wyoming native plants require cold stratification for germination of seed. “Cold stratificaton” is a fancy term for “needs some time spent in cold dirt.” It’s easy to understand. If a northern plant naturally distributes its seeds in the autumn, those seeds will spend the winter being subjected to cold and rain and snow, and even intermittent periods of dry cold.

cold stratification of native plant seedsI have reproduced this environment for seeds by placing flats of planted seeds in freezers and refrigerators, and I have had pretty good success. But this year I am doing it the old fashioned way, by placing my flats outside under some large shade trees and  covering them with a thin layer of leaves. It’s easy, low labor, and works great for the native plants who self sow here.

Today I sowed some of my favorite native Wyoming plants for my landscaping efforts in 2011:  Eriogonum umbellatum, Antennari, Amelanchier alnifolia, Ceanothus velutinus, Epilobium angustifolium, and Penstemon angustifolius.

In the past, I have planted Antennaria in the early spring with good germination rates, but the seeds are so fine and difficult to prevent from washing away. So this year I am going to sow them now in a flat, let them germinate where I can keep track of them, then move them in clumps into the garden.

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