Can Garden Seeds Be Frozen?
If you want to store garden seeds for the long term, you may have wondered whether freezing them is a good idea. While some gardeners swear by freezing seeds to extend their viability, others worry about potential damage. So, what’s the truth? In this article, we’ll explore whether freezing garden seeds is a safe and effective storage method, which seeds handle freezing best, and the right way to freeze and thaw seeds for future planting. Whether you’re saving heirloom varieties or stocking up for next season, this guide will help you make the most of your seed storage strategy!
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How To Freeze Seeds
There are a few things you will need to do to correctly store garden seeds in the freezer. The first is to ensure the seeds are completely dry before storing them. This is one of the most important steps, as humidity and moisture can affect the longevity of the seeds as well as cause them to crack or split when stored in the freezer.
The best way to dry seeds is to allow them to dry naturally. Spread seeds out on a baking sheet or newspaper, leaving space between each seed so they are not touching. This allows for air to reach each seed. After one week, gently move the seeds around with your finger, then let them dry for another two to three weeks.
Another method is to place the seeds in a sealed jar with a silica gel package for one to two weeks—Silica gel works by drawing out and absorbing moisture from the air. You often find these in purses and online order packages. After a week or two, remove the silica gel.
After the seeds have been dried, transfer them into either an airtight container or freezer bag and store them in the freezer. A helpful tip is to label and date each container to avoid any mix-ups when it comes time to thaw your seeds.
How Long Do Seeds Last In The Freezer
Seeds can last between three to five years in the freezer as long as they are completely dried before storing. Hardy vegetable seeds could last even longer as they are more resilient to colder temperatures. Even seed banks freeze their seeds for long-term storage, though they are under better-controlled environments than our freezers at home. It will still do the trick if you only plan to keep them stored for a few years.
Will Seeds Germinate After Being Frozen?
Seeds will germinate after being frozen. In fact, some seeds will germinate better after freezing as this simulates the natural conditions the seeds would experience if planted over the winter. However, you may run into some issues if they are correctly stored in the freezer.
Some seed varietals require exposure to cold temperatures before planting. This is called cold stratification. This process puts the seeds in a dormant state and helps improve their germination rate. While most vegetable crops do not need stratification, many flowers, trees and medicinal herbs will benefit. Here are a few examples of seeds that require cold stratification: Lupine, Milkweed, St. John’s Wort, Morning Glory, Sweet Pea and Perennial Sunflowers.
How To Thaw Frozen Seeds For Planting
As you can imagine, letting your frozen seeds thaw before you begin planting them is important. To do this, take the seeds out of the freezer and let them sit at room temperature for around 24 to 48 hours. Once they are no longer frozen, you can either begin to germinate or directly sow them, depending on the type of seed.
Which Seeds Cannot Be Frozen?
While many seeds can be frozen, recalcitrant seeds cannot be. These seeds cannot be dried below relatively critical moisture levels, nor can they handle temperatures below 50 °F (10 °C). In addition, they cannot be stored for long periods as they germinate quickly, making it best to use them fresh to ensure viability. Recalcitrant seeds include mango, lychee, coffee, avocado, sweet chestnut and cocoa.
