Building Digital Education of Heirloom Crops
for the Resilience of African Food Systems in the Climate Crisis
Lecture 7
Harvest and Save the Seeds!
Collecting, preparing, and preserving seeds
Seeds should be harvested when they are fully ripe. If you wait too long, they may mold or fall off. Seeds should not be collected from damaged or rotten fruits.
Tip: When storing, fermenting, or sprouting seeds, label each container with the species and variety.
Some seeds are harvested wet, and others must be dry.
Wet seeds
Wet seeds are tomatoes, cucumber, pumpkin, melon, and capsicum.
Tomatoes
The fruit must be very ripe. Do not choose the first fruit, but the best ones in the first clusters. If the fruit is unevenly developed, not all ovules are adequately pollinated. Put a marker on your chosen fruits to avoid losing them to a hungry mouth.
There are two ways to handle tomato seeds.
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First:
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Cut the tomato open and squeeze the seeds and juice into a cup. The rest of the fruit can be eaten. Add some lukewarm water to the cup and leave it in a warm place.
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After a couple of days, a moldy surface will form. Now, pour water, mold, and seeds into a strainer. Rub gently with your fingers under running water until the seeds are clean.
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Tip seeds from the strainer onto a piece of non-absorbent / sandwich paper.
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You can scratch them off with a knife and store them in a paper bag when dry.
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Second:
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Cut the tomato open and distribute the seeds evenly on a kitchen paper towel. The slime around each seed will be glued to the paper when dry.
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Let the paper dry completely and store it in an envelope.
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When you are ready to sow your seeds, you just remove the extra layers of kitchen towel. Then, spread the paper over your seedbed, cover it with soil, and add water. The paper will disappear while the seeds are germinating.
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The first method's advantage is that the seeds occupy very little space. The second method's advantage is that the seeds are easy to sow, and the plants grow at your chosen distance.
Cucumber
A ripe cucumber is yellowish and soft, but do not wait too long. If not harvested in time, the seeds might germinate. Scrape out the seeds, wash them, and dry them on a piece of non-absorbent sandwich paper.
Pumpkin and melon
You don't need to remove the seeds until you want to eat your pumpkin or melon. Just scoop out the seeds, wash them, and dry them on a piece of non-absorbent sandwich paper.
Capsicum
Harvest seeds from ripe pepper and chili fruits. Seeds dry in a day when left on a piece of paper or a plate. If your chilies are hot, remember to wear gloves.
Dry seeds
Most other seeds are to be harvested dry.
Pay attention to your seed plants because dry seeds will mold if they get very wet. Furthermore, some plants ripen their seeds successively over a long time, and you have to harvest the first before the last are ready. Rub with your hands or cut with a pair of scissors into a paper bag or bowl.
The autumn weather often does not cooperate with seed savers. If your dry seeds are in danger of getting very wet, gently pull the whole plant from the ground, brush or rinse the roots free from dirt, and hang the plant upside down in a dry and airy place. A carport is well suited for this purpose. Do not forget to put a paper bag over the top of the plant to prevent seeds from being lost if they drop off while drying.
Seeds die at about 35 degrees Celsius, so do not dry them in direct sunlight or an oven. Slow and airy drying is better for seeds than hot and fast drying.
Seed drying and preservation
Seed cleaning
Describing in words the different techniques for cleaning seeds might make it sound complex, but it is not necessarily that bad. It takes some creativity and practice to make it happen – the easiest way to get the idea is by watching an experienced seed saver in action.
Working gloves with rough palms are excellent for rubbing seeds from their hulls. Ripe pea or bean pods can be beaten or walked upon in a cloth bag or pillowcase. A set of sieves with holes in different sizes is handy, too. Finally, you can winnow seeds using baskets or bowls.
Removing insects, including larvae, pupae, and other wet stuff, is the most important part of seed cleaning. If your seeds are dehydrated and free of pests, they have a good chance of germinating next year.
Documenting your seeds
When collecting seeds, create a 'seed passport'. Place the seeds on a graph paper or use a ruler to scale and record their size. Note the source of the seeds, their name, and basic information about the plant's characteristics and growing conditions. Photographing this 'seed passport' will provide a well-documented record of the seeds received.
This will help you remember where the seeds came from and how to grow them.
Freezing seeds
Freezing is a simple and effective method to protect your seeds from pests and ensure a healthy and abundant harvest the following year. However, following the correct freezing techniques is essential to avoid damaging the seeds.
Freezing duration: Seeds should be frozen for at least 5 days but no longer than 2 weeks for maximum effectiveness. Longer freezing can negatively affect seed germination.
Temperature: The optimal temperature for freezing seeds is -18°C. If a freezer with such a low temperature is not available, a regular household freezer will suffice.
Packaging: Pack the seeds in small paper or cloth bags before freezing. Plastic bags can promote moisture condensation, which can negatively affect the seeds.
After freezing: The seeds should be thoroughly dried in a cool, well-ventilated area.
Why is freezing so effective?
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Pest elimination: Low temperatures kill most seed pest eggs and larvae.
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Disease prevention: Freezing can also help prevent some seed diseases.
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Improved seed vitality: In some cases, freezing can even improve seed germination.
Important to remember:
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Not all seeds are the same: Some seed varieties may be more sensitive to freezing than others. Before freezing, it is advisable to consult with experienced gardeners or search for information about the specific variety.
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Regular seed replacement: Even with all the necessary measures, seeds can degenerate over time. Therefore, it is essential to regularly renew seed stocks by obtaining new seeds from reliable sources.
Hot water treatment
Hot water treatment is another excellent method for disinfecting seeds and eliminating pest eggs. This method suits larger seeds such as beans, peas, and corn.
Why does hot water work?
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Thermal shock: The high temperature kills most seed pest eggs and larvae without affecting the seeds' viability.
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Softening of the seed coat: Hot water softens the seed coat, promoting faster germination.
How to perform hot water treatment:
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Prepare the water: Heat the water to approximately 50°C.
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Place the seeds: Place the seeds in a suitable container (e.g., a sieve or colander) and immerse them in hot water.
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Soak time: The soaking time depends on the type of seed, but 20-30 minutes is usually sufficient.
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Cooling: After soaking, cool the seeds by pouring cold water over them.
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Drying: Dry the seeds until they are completely dry.
Important to remember:
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Seed types: Not all seeds tolerate hot water treatment equally. Tiny seeds may be more sensitive and can burn.
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Temperature: Too high a temperature can damage the seeds.
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Time: Too long exposure to hot water can negatively affect germination.
Germination test
Test your seeds this way:
Place several layers of paper kitchen towel on a plate and water it thoroughly. The paper must be wet all over but not soggy. Separately, place 20, 30, or 50 seeds on the paper, cover it with kitchen foil, and put it in a warm place. Do not forget to label the plate with the variety and date.
Remember to check your seeds once or twice daily and add water if the paper dries. After a few days, you might see the first germination, but be patient; it might take up to three weeks before your seeds germinate. When no more seeds are germinating, you can count and calculate the percentage of your seeds likely to germinate in the garden (usually a little less than in the kitchen).
If a larger number of seeds must be germinated, this tilted jar method is the most convenient.
How to sprout:
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Rinse in cold water.
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Choose a jar of suitable size - large enough so that the sprouts are less than 1/3 of the jar.
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Soak overnight in a large amount of water, especially legumes, which swell well. Cover with cheesecloth and secure with a rubber band.
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In the morning, rinse through the cheesecloth. You may need to hold it to prevent everything from being washed away.
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Tilt the jar and let the sprouts grow.
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Rinse the sprouts with cold water every evening and morning to prevent mold.
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When the seeds have sprouted, count the sprouted and unsprouted seeds and calculate the germination percentage. Record the germination percentage on the seed packet and the month and year of germination.
After a couple of days, it looks like this:
Sprouted seeds can also be eaten. Grains, sunflowers, peas, and seeds can be consumed fresh. However, sprouted beans should be cooked. Any method can be used for sprouting if moisture is provided and mold is prevented.
Even if you have never sprouted seeds before, don't hesitate to try it. It is simple, and practice makes perfect. If something does not work out, try again, and you will gain experience and skill.
Storing
Keep your seeds in a cool, dark, dry place, and safe from mice. That is the secret to storing them right! The best temperature is around 5-10°C. You can use glass jars, paper bags, or special seed storage bags. Make sure to label each package with the type of seed, variety, and when you harvested them.
References:
[1] - Growing Seed Savers. (2019). A Guide To Seed Saving [Brochure].
https://growingseedsavers.org/content/pdfs/GSS_Guide_to_Seed_Saving_ENG_Spreads.pdf
[2] - Frosamlerne (2019). Presentation "Basics about seed saving", project "Growing Seed Savers", https://growingseedsavers.org/educational-program-for-seed-saver/ .
[3] - Diyseeds (2022), https://www.diyseeds.org/en/films/ [Movies]
The content of this page was created as part of the project 'Building Digital Education of Indigenous Inherited Crops for the Resilience of African Food Systems in the Climate Crisis Development.' The project was funded by the Ministry of Foreign Affairs in 2024 from the development cooperation budget. This content reflects only the views of the project partners.
