Germination of Tree Seed: Growing Trees Can Be Fun

by Richard Jauron, Department of Horticulture, Iowa State University

Note: This article was published originally in 2000 by Richard Jauron, Department of Horticulture, Iowa State University, in Horticulture & Home Pest News. While some of the species mentioned are more typical of the eastern United States, there are many good tips and references that could be applied to Texas trees. - DFW, Ed.

Germination of tree seed, and growing trees from seed can be fun. However, the seed of most tree species won't germinate immediately when planted because they are in a dormant state.

Dormancy must be broken before the seed can germinate. In some tree species, dormancy is the result of a thick, hard seed coat. The seed coat may be broken in a variety of ways and the process is referred to as scarification. Mechanical means, such as a metal file or coarse sandpaper, can be used to break the seed coat. Treatment with boiling water has also been successful for a number of tree species. In nature, the seed coat may be broken by microbial action, passage of the seed through the digestive tract of a bird or other animal, exposure to alternate freezing and thawing, or fire.

The seed of many tree species will not germinate until they have been exposed to cool temperatures and moist conditions for several weeks or months. Winter weather in areas of the United States such as Iowa provides the necessary conditions to break dormancy. Gardeners can accomplish the same results by a process called stratification. Tree seed can be stratified by placing the seed in a moist 50:50 mixture of sand and peat moss. Suitable containers include coffee cans, plastic jars, and cottage cheese containers. (Punch holes in the lid of the container to provide air.) Seed can also be stratified in plastic bags. Stratify the seed in the refrigerator.

The seed of some trees, such as redbud, have hard impermeable seed coats and dormant embryos. They require both scarification and stratification for germination. Specific information on collecting and planting seed from several tree species follows:

Excellent references on the propagation of trees and shrubs include The Reference Manual of Woody Plant Propagation by Michael Dirr and Charles Heuser Jr., Plant Propagation: Principles and Practices by Hudson Hartmann, Dale Kester, Fred Davies Jr., and Robert Geneve, and Seeds of Woody Plants in North America by James Young and Cheryl Young.

This article originally appeared in the August 11, 2000 issue, pp. 102-103, 2000, Issue: IC-483(20), Horticulture & Home Pest News -- Richard Jauron, Department of Horticulture, Iowa State University.

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