In the Garden:
Northern & Central Midwest
November, 2009
Regional Report

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These paperbark maple seeds need a cool, moist period followed by a warm moist period to break dormancy and germinate.

Seeds, Seeds, Seeds

As the fall begins to wind down, the leaves are dropping and many trees and shrubs are leaving behind their seeds to start new plants next year. It's hard not to be tempted to help nature along and collect seeds to start plants on our own.

Starting your own plants from seed can be extremely rewarding, not to mention saving you money by growing your own plants. However, seeds from woody plants may have a few issues that you need to be aware of in order to be successful at getting them to germinate.

Woody Seed Dormancy
Many woody seeds have dormancy characteristics that need to be overcome before the seeds will even begin their growth process. They must take in water to begin the germination process, and some seeds actually have methods for preventing water from being absorbed.

Tree and shrubs do this to assure species survival. The seeds have internal controls that make sure their seeds only germinate in nature when conditions are perfect and the season is right. This mechanism creates a natural seed bank by not allowing all seeds to germinate in one year.

Physical Dormancy
Sometimes this mechanism is a physical one in which the seed coat is too hard or has a waxy coating that water cannot penetrate. Nature takes care of this by several methods: If the seed is eaten by an animal, it passes through the gut where it is exposed to acids that break down the seed coat. If it simply falls to the ground, the seed coat can be broken by the freeze-thaw cycle in winter. If the seed blows around, it gets nicked and scraped by rolling across rough ground.

Scarifying Seeds
To get these seeds ready to absorb water, we need to mimic one of these methods. We can scarify the seeds by dipping them in sulfuric acid or sometimes hot water. To nick the seed coat, all it takes is a swipe across sandpaper or a metal file.

Some seeds actually have chemical layer beneath the seed coat that prevents oxygen from entering. For these seeds, we can remove the seed coat and then, depending on the seed, rinse it in hot water or heat it in the oven. It's necessary to be sure of what you are doing, though, because too much heat can kill the seed.

Internal Dormancy
Some seeds have an internal control that isn't released from dormancy unless it goes through a natural winter cycle. We can speed up this process by stratifying the seeds which basically means giving the seed cold and then warm temperatures. The seeds are collected, put in moist sphagnum moss and then chilled for a designated amount of time. Then the seeds are brought into warm conditions, allowed to absorb water and then they will germinate.

Information about individual seeds is available on the Internet, so make sure you check it out before getting frustrated!


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