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Growing Plants from the Wild

Native seeds need to cool down before sprouting

Seeds of native plants in the temperate region require chilling, called stratification, before they can germinate and grow seedlings. The acorn of the mighty oak must be stratified before it can germinate in the spring. But don’t go placing acorns in the freezer before planting.
    In nature’s cycle, acorns fall to the ground in the fall, while the ground is still warm and moist. On the ground, some are covered with leaves; some are gathered and buried by squirrels. Soon after landing, acorns begin to absorb moisture. Slowly, the ground cools. As soon as soil temperatures drop to near 45 degrees, stratification begins. When soil temperatures drop below freezing, stratification stops. As temperatures rise above freezing, stratification continues. Nature’s alternate freezing and thawing enhances germination.
    Each plant species has its own length of time for stratification. In species that grow over a wide range of latitudes, stratification periods can vary considerably. For instance, the red maple tree has a growing range from ­Quebec to northern Florida.
    The stratification period for seeds taken from trees native to Quebec is shorter than for seeds from trees native to northern Florida. This is because the ground freezes earlier and stays frozen longer in Quebec than in northern Florida. In northern Florida the soil seldom freezes hard, but it is cold enough that seeds germinating in early spring would be killed by frost. This phenomenon was verified when red maple seeds harvested from trees growing near Quebec were planted in northern Florida and seeds harvested from red maples originating in northern Florida were sown in soil near Quebec. The Quebec seedlings germinated in the middle of Florida’s winter and were killed by frost, while the seeds from Florida never germinated in Quebec.
    To artificially stratify seeds from our region, mix them with moist sand blended with some peat moss and allow them to absorb moisture for at least two weeks. Then refrigerate for another six to eight weeks before sowing. This is more or less following the normal daily temperature cycle.
    The lazy way of germinating native plant seeds is to sow them in the fall in a well-prepared soil with at least three percent organic matter. Cover the seedbed with a board to prevent winter weeds from growing. The seeds will undergo natural stratification.
    In the spring, at about the time the buds of trees are starting to show color, remove the board covering the seed bed and watch for seedlings to emerge.


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