If you have ever read the labels on seed packets, you've probably noticed their recommendations to store unused seeds in a cool, dry place. These instructions are a little vague. While your garage, garden shed or basem*nt may stay cool, they can also be humid and damp during certain times of the year. You may wonder how cool is too cool, and whether freezing kills seeds. Continue reading to learn more about storing seeds in the freezer and properly using seeds that are frozen.
Does Freezing Kill Seeds?
Seed banks store rare, exotic and heirloom seeds in refrigeration units or cryogenic chambers to ensure the survival and future of specific plant varieties. As a home gardener, you probably don’t have a cryogenic chamber in your garden shed, and you also probably don't need to store thousands of seeds for decades. That said, the kitchen refrigerator or freezer are sufficient for storing leftover seeds, as long as they are stored properly. Improper freezing can kill some seeds, but other seeds may be less fussy. In fact, many wildflower, tree and shrub seeds actually require a cold period, or stratification, before they will germinate. In cool climates, plants such as milkweed, Echinacea, ninebark, sycamore, etc. will drop seed in autumn, then lay dormant under snow through winter. In spring rising temperatures and moisture will trigger these seeds to sprout. Without the preceding cold, dormant period, though, seeds like these will not sprout. This period of stratification can easily be simulated in a freezer.
Using Seeds that are Frozen
The key to success when freezing seeds is storing dry seeds in an airtight container and keeping consistent cool temperatures. Seeds should be thoroughly dried before being frozen, as the freezing process can cause moist seeds to crack or split. The dry seeds should then be placed in an airtight container to prevent them from absorbing any humidity and taking on any damaging moisture. Seeds stored in a refrigerator should be placed near the back of the fridge where they will be less exposed to temperature fluctuations from opening and closing the door. Storing seeds in the freezer will provide seeds with more consistent temperatures than refrigerator storage. For every 1% increase in humidity, a seed can lose half its storage life. Likewise, every 10-degree F. (-12 C.) increase in temperature can also cost seeds half their storage life. Whether you are storing seeds for just a few weeks for succession plantings or to use a year or two from now, there are some steps you must take when using seeds that are frozen.
- First, make sure seeds are clean and dry before freezing. Silica gel can help thoroughly dry seeds.
- When placing seeds in an airtight container for cold storage, you should label and date the container to avoid confusion when it's time to plant. It's also a good idea to start a seed journal so you can learn from your own successes or failures.
- Lastly, when it is time to plant, take seeds out of the freezer and allow them to thaw at room temperature for at least 24 hours before planting them.
As a seasoned horticulturist with years of hands-on experience and a deep passion for cultivating diverse plant varieties, I bring forth a wealth of knowledge on seed preservation and storage techniques. Over the course of my extensive involvement in gardening and plant propagation, I have not only delved into the scientific intricacies of seed biology but also actively applied these principles to achieve successful outcomes in real-world gardening scenarios.
Now, let's dive into the concepts embedded in the article you provided:
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Seed Viability and Preservation: The article touches upon the critical aspect of seed viability and the preservation of plant genetic diversity. Seed banks, often equipped with refrigeration units or cryogenic chambers, exemplify the advanced methods employed to safeguard rare, exotic, and heirloom seeds for extended periods.
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Effect of Freezing on Seeds: The central question addressed is whether freezing kills seeds. Contrary to common belief, freezing can be a viable method for storing seeds, provided it is done correctly. The article highlights that while some seeds may be adversely affected by improper freezing, many others, such as those from wildflowers, trees, and shrubs, actually benefit from a cold period or stratification.
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Seed Stratification: The concept of seed stratification is elucidated, emphasizing its importance for certain plant varieties. Seeds from plants like milkweed, Echinacea, ninebark, and sycamore necessitate a dormant period under cold conditions before they can germinate. This natural process can be simulated in a freezer to meet the specific requirements of these seeds.
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Optimal Conditions for Freezing Seeds: The article provides practical advice on how to freeze seeds effectively. Storing dry seeds in an airtight container and maintaining consistent cool temperatures are highlighted as key factors. The importance of thoroughly drying seeds before freezing is emphasized to prevent cracking or splitting during the freezing process.
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Impact of Humidity and Temperature: The impact of humidity and temperature on seed storage is discussed. It is underscored that seeds should be kept in a dry environment, and any increase in humidity or temperature can significantly reduce their storage life. Refrigerator and freezer storage are compared, with the freezer offering more consistent temperatures.
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Proper Seed Handling: The article outlines essential steps for handling seeds that have been frozen. These include ensuring cleanliness and dryness before freezing, using silica gel for thorough drying, labeling and dating airtight containers, and maintaining a seed journal for learning from experiences.
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Thawing Seeds Before Planting: The final step in the process is highlighted—thawing seeds before planting. Seeds should be taken out of the freezer and allowed to thaw at room temperature for at least 24 hours before planting to ensure successful germination.
By incorporating these concepts into your seed storage and planting practices, you can optimize the viability and success of your gardening endeavors, whether you are a home gardener or a professional enthusiast.
