Jul 6, 2023
There are many ways to preserve seed, all of which involve taking out the water content. The problem is if not done right, dozens, if not hundreds, of seeds end up getting wasted. As a gardener, farmer, or someone who is growing their own food, you may be wondering. Can seeds be freeze dried?
The great thing about freeze-drying seeds is that you have a controlled environment. No temperature fluctuation or exposure to unnecessary elements can ruin the process. This leads to irreparable tissue damage that weakens the seeds.
The first indication of a bad preservation is the loss of vigor. This is when the seeds fail to germinate or germinate at a slower rate. There’s also less resistance to attacks of microorganisms.
When you freeze dry seeds, you take out the moisture content makes them prone to damage when stored. Since you take out moisture way more than standard drying, you have seeds that last longer and are less prone to microbial damage.
A YouTuber made an experiment of freeze-drying garden seeds. He did this in July and tried germinating it after a month. He used 4 different crops, each with 20 seeds, to see the viability after freeze dying. In the 20 seeds that he freeze-dried, he got 14-20 seeds to germinate. Some germinated quite well, while others were a bit slow compared to the control group. But do note that his experiment was done within a month of freeze drying.
On the other hand, the head engineer at Harvest Right freeze-dried seeds as well. All 10 different vegetable seeds germinated under grow lights in his home. Transplanted in a Garden Right geodesic dome greenhouse, the vegetables grew to maturity.
There are several advantages of freeze-drying seeds.
This means you have viable seeds to plant next year. This is highly useful, especially when you’re practicing crop rotation. By cycling the crops you plant, you prevent depleting the soil of nutrients and the growth of harmful microorganisms.
Drought and floods are known to kill plants before they reach maturity. And if plants don’t produce, you won’t get seeds to plant for the next season. By freeze-drying seeds, you still have your backup seeds to plant for another harvest.
If done right, you have seeds that will germinate faster compared to dried seeds. This means you have ample time to plan your crops. Then, you can either avoid or take advantage of the season’s weather to produce the best crops with the best yield.
Most of the time, you get your seeds from remote seed banks. The problem is, they’re either geologically or politically unstable. This can interfere with your supply and cause delays in planting. On the other hand, when you freeze-dry your own seeds, you have a stock that you can take advantage of any time you want.
That would depend on the type of seeds. Remember when we talked about freeze-drying grapefruit and we mentioned taking out the seeds? Grapefruit seeds have a thicker membrane and flesh. This makes it harder for the freeze dryer to do its work and dry the seeds thoroughly. But if done right, the seeds can last for years. In general though, this is how long seeds will last after preservation.
Freeze drying seeds is a bit more complex and longer than freeze drying food. It involves several stages, from preparing the seeds to the actual freeze-drying process.
Check which of your plants are robust, producing awesome produce, and are stronger against pests. Ignore the ones that are weak, stunted, and growing low-quality produce. Remember that you’re storing seeds for future use, so you need to pick the healthy ones.
Cleaning helps remove flesh and debris that can interfere with the drying process. Place the seeds in a fine mesh sieve and wash them under running water. Scrub out as much flesh from the seeds as you can.
Fermentation helps take out bad, sickly seeds. Place your cleaned seeds in a container and label them according to the plant variety. Add 1/4 cup of water or until you submerge all the seeds. Keep the container in the shade for a few days. Don’t mind the foam that forms on the bottom. After 3-5 days, remove the moldy film from the water, then dump out the water.
Sort out the seeds by adding fresh, clean water. Bad seeds will float while the good seeds will sink. Dump the bad seeds and take out the clean, good ones. Throw away the water and drain off the excess moisture from the seeds by laying them on paper towels. Afterward, spread the moist seeds on paper plates to dry.
Before you freeze-dry the seeds, you have to dry them first. This is to prevent the seeds from expanding and cracking during the freezing process.
Place the seeds in an airy room or under the sun to dry. We recommend drying in a cool, dry place with ventilation to prevent heat from ruining the seeds. Drying time depends on the seeds. When you have a forced air flow in the drying room, small seeds take 24-48 hours to dry. Larger seeds like pumpkin and sunflower seeds take 7-10 days.
Place the seeds on a tray and put them in the freezer. Since you’re dealing with something that has life in it, it’s crucial that you keep this stage stable. Keep the freezer door closed for 24 hours until the seeds are frozen.
Prepare the freeze dryer to the proper cooling temperature. Once the freeze dryer’s ready, take out the seed tray and place it immediately inside the freeze dryer. Don’t wait for the seeds to sit long outside before placing them inside the freeze dryer. We don’t want ice crystals to form inside the seeds, so let the cycle run until the seeds are dry.
You can store the freeze-dried seeds in Mylar bags, with an oxygen absorber thrown in. For added measure, you can also put in some desiccants to take out any excess moisture. Remember to label the bag with the seed types and the date when you prepared them. Finally, seal the seeds and store them in a cool, dry, dark place.
Unlike food, the ideal storage temperature for seeds is 35°F-40°F. This prevents the seeds from germinating prematurely. Keep the temperature at constant as much as possible. Shocking the seeds with sudden temperature drops and rises will weaken the seeds’ viability.
What’s your take on freeze-drying seeds? Have you tried them? Let us know in the comment section.
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