If you’ve grown before, you know the excitement of a beautiful harvest. Getting seeds from your harvest to ensure you can produce the same plant is usually a thought growers come across. Unfortunately, a lot of people don’t know how to store seeds for later use. Here are some of the basics on seed storage.
Basically, a seed needs for storage the opposite of what they need for germination (oxygen, heat, moisture, and light).

Types of Seeds

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Heirloom Seeds If you are growing a garden with the intent of being self-sustained and saving your own seeds for the next year harvest, then heirloom and open pollinated seeds are what you should look for. They will produce a reliable and consistent crop, year after year.

Hybrid Seeds (F-1, F-2) This seed will produce true to form only once. So, if you grow your favorite F-1 hybrid broccoli – that one that puts out great side-shoots – you cannot save the seed and expect to get the same plant next year.  Hybrid seeds are only good for one year.

Seed Tolerance

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For purposes of storage, there are basically two types of seed: ‘desiccation-tolerant’ and ‘desiccation-intolerant’. Most of the garden plants that we are familiar to produce desiccation-tolerant seeds, which means they can be safely dried for long-term storage. Exceptions include many aquatic plants, large-seeded plants, and some trees (such as oaks and buckeyes), many of which produce desiccation-intolerant seeds and will die if allowed to dry.

Desiccation-Intolerant seeds do not enter dormancy after maturing. Instead, respiration and other physiological processes continue. Continued respiration after maturation causes desiccation-intolerant seeds to deteriorate rapidly once they have matured, so they must be planted while still fresh. Desiccation-intolerant seeds partially or completely lose viability if they are allowed to dry—usually, they die.

Since desiccation-intolerant seeds must be stored moist, they can only be kept for short periods of time before they begin to succumb to fungal or bacterial rots or run out of stored food reserves because of continued respiration.

Desiccation-tolerant seeds prepare for dormancy by greatly slowing or ceasing most physiological processes, and by converting food reserves from sugars to more stable fats and starches. After they have prepared for dormancy, and unlike desiccation-intolerant seeds, desiccation-tolerant seeds can be safely dried and stored for long periods of time without significant loss of viability (many years in some cases). Some desiccation-tolerant seeds even require drying to complete the ripening and dormancy process before they will germinate.

How desiccation-tolerant seeds are dried and stored is very important to maintaining their viability and vigor over the long term. Drying should be gradual and thorough, and desiccants should be used when drying seeds in air above 30% relative humidity or so. During storage, seeds must be kept at an appropriate temperature and moisture levels for greatest longevity. Using a dry paper towel to dry your desiccation-tolerant seeds is very common.

Gathering Your Own Seeds

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If you’re gathering and saving seeds from your own plants, spread the seeds on newspaper and let them air-dry for about a week. Write seed names on the newspaper so there’s no mix-up. Pack the air-dried seeds in small paper packets or envelopes and label with plant name other pertinent information. Remember, if you want to save your own seeds, you’ll need to plant open-pollinated varieties. They’ll come back true; hybrids won’t.

Always realize, virtually all seeds will have weaker germination over time. Seed moisture content: Before storing your seeds, it’s important that their moisture content is between 5%-8%.

Using Nutrients

A nutrient rich environment increases genetic variability. This means the chances for a really special “super seed” to be produced is greater if your nutrient concentration is higher. So if you plan to grow your own seeds, use as high a nutrient concentration as your plants can tolerate. Decreased nutrients also reduce seed weights and the total number of seeds. Nutrients to use should be organic and natural. Companies like Complete Hydroponics have special nutrients to use on all plant types and all growing media that help keep plants strong and healthy and help them produce strong and healthy seeds.

 

 

Rice Drying Technique

  1. Spread enough rice to fill a canning jar 2/3rd’s full onto a baking tray. Do not grease your pan.
  2. Bake the rice at 350 degrees, for 45 minutes, or until it is bone dry.
  3. Place the still warm rice into your canning jar and tighten the lid. This prevents moisture from the air re-hydrating the rice.
  4. WAIT patiently for it to cool
  5. Once the rice is completely cool, place your seeds in a paper seed packet, muslin or mesh bag, and place it in the jar with the rice. Be sure and tighten the lid so moisture stays out.
  6. After 2 weeks in the rice jar, your seeds will have been thoroughly dried and are now dormant and ready to store.

Powdered Milk Technique

Powdered milk can also be used as a desiccant. Use one to two tablespoons of milk powder from a freshly opened package. Wrap the powder in a piece of cheesecloth or a facial tissue and place it in the container with the seeds. Powdered milk will absorb excess moisture from the air for about six months.

Containers 

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Plastic containers are not good for storing, neither are Ziploc bags by themselves. Plastic will allow air and moisture in. Glass containers are by far the best option for a storage container. Mason jars or the wire bale air seal glass jars have been shown to be the best seed storage container. Using foil pouches is a great addition when used to cover the seeds inside the glass jar because the foil also blocks out the light.

Storage Conditions 

  • Oxygen – A low oxygen environment is crucial to long term seed viability. Exposure to oxygen will cause a much more rapid deterioration of seeds. Low oxygen can be achieved by simply keeping seeds in an air tight jar. Vacuum sealing is fine but not always needed. If the seed moisture content is above 10%, then vacuum sealing will definitely help but if the seed moisture content is below 10%, studies have shown no noticeable increase in viability from vacuum sealing.
  • Temperature – Low temperature slows down the metabolic process of the seed and is important for proper storage. 0 degrees Fahrenheit has been shown to be the optimum temp. Anything below 28 degrees is good but 0 is best. Anything lower though can harm a seed.
  • Light – Exposure to light will cause faster deterioration in many kinds of seeds but not all kinds.
  • Use of Silica gel packets – Silica gel packets are an excellent addition to your storage container. They can absorb any stray moisture and help keep things dry.
  • Condensation – Condensation is bad for seeds. Regular opening and closing of your freezer can lead to condensation forming. That is why placing them behind a double barrier will help if any condensation does form. For instance putting them in a Ziploc, foil lined seed pouch inside a mason jar is good. It’s also why a silica gel packet is a great idea in your container.
  • Humidity – A humidity level of higher than 5% but less than 10% is desirable. Anything higher will lead to faster degradation and anything lower can lead to seed desiccation (drying out).

Bringing Seeds Back To Life

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When seeds are removed from cold storage in order to retrieve samples, allow the entire container to come slowly to room temperature before opening the seal. This will help prevent condensation of atmospheric moisture onto the cold seeds which might otherwise occur. There seems to be some evidence that seeds should be removed from the freezer a couple days before germinating them.

Accept Any Losses

Even if you’re organized, methodical, and careful about storing seeds, accept the fact that some seeds just won’t germinate the following year.

 

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