Return seeds

Liaison librarian
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Seed saving basics

I hope you have all had a successful gardening season. As you harvest your bounty, you may be thinking about saving some of your seeds to return to the Seed Library. Returning seeds is not a requirement for using the Seed Library, but we do encourage it! Should you decide to return some of your seeds, please carefully read and follow the guidelines below.

You can then fill out the “Seed return form” and include it with any seeds you wish to return. If you are returning seeds to a branch other than the Macdonald Campus Library, you may bring them directly to the service desk of any McGill branch library (be sure to inform the staff member at the desk that you are returning seeds to avoid confusion!). Please ensure that all seeds are properly labelled and that they are well packaged to avoid seeds spilling on their way to the Seed Library.

If you have any questions, please do not hesitate to contact macdonald-seed.library [at]


Healthy plants. Save seed from your best plants. Strong, healthy plants are most likely to produce good seed and pass on good traits to the next generation.

Genetic diversity. If the population size of a particular variety is too small, there may be too little genetic diversity for the plants to produce good seeds (species that are mostly or entirely self-pollinating, such as peas, require fewer plants to maintain genetic diversity than out-breeding types, such as spinach). In general, the more plants the better, but good seed can be obtained from only a few plants in some species.

Give plants some space. Some plants, such as peas and tomatoes, are largely or entirely self-pollinating, which means they do not readily cross with other related species. Others, such as melons and squash, are pollinated by insects or by the wind, so they easily cross with other plants of the genus. The fruits the plants produce will be true to type no matter what, but if they cross-pollinate, their seeds will grow into hybrid varieties. While this can make for some interesting experiments, it is undesirable from a seed preservation perspective. Cross-pollination can be avoided by planting different crossing types far enough apart, or simply by planting only one member of a cross-pollinating genus in your garden. If you believe some of your plants had the opportunity to cross-pollinate, please do not donate these seeds.

Start with easy plants. Peas, beans, lettuce, tomatoes are self-pollinating plants and their seed is easy to save for the novice gardener and seed-saver. If you have not saved seed before, these are excellent plants to start with.

Know when your seeds are ready. Not all seeds are ready at the same time as the fruit. Vegetables such as snow peas, summer squash and cucumbers are eaten when the seeds are small and immature. If you want to save seeds from these plants, leave some of the fruit on the plants to allow the seeds to mature (choose some of the best, healthiest-looking fruits for the best seeds!).

Know how to harvest seeds. Harvesting some types of seed, such as peas or corn, is as easy as picking the dry fruits off the plant and packaging up the seeds. Other types, such as tomatoes, require a few steps to save good seed. The process is not difficult, but it should be followed carefully to ensure viable seeds.

Know how to store seeds. Ensure that seeds are fully dry before packing them up, as residual moisture can harm them. Store prepared seeds in sealed containers (such as airtight plastic containers or freezer bags) and keep them in a cool, dark, dry place. Be very careful to keep them away from any moisture, since any water may cause them to rot or to germinate prematurely.

Run a germination test. This test allows you to find out how many of your seeds are viable for future growing. Non-viable seeds may be caused by a weak or diseased source plant, improper saving or storage techniques, or age. It’s important to test your seeds to ensure that you do not return non-viable seeds to the seed library. A germination rate of 70% or higher is suitable for returns.

  1. Moisten paper towel (wet but not dripping).
  2. Select seeds to be tested at random. 10 seeds are the minimum for testing purposes.
  3. Place seeds on one side of the paper towel. Fold paper towel in half and place inside a partially sealed plastic bag that has been labeled to indicate variety.
  4. Place seeds in a warm location.
  5. Check seeds every day for 10-14 days. Seeds that sprout are counted as viable, seeds that fail to sprout or become molded or rotted are marked “not viable”. Keep paper towel moist (a spray bottle is a good way to do this).
  6. Calculate your seed viability (i.e. if 12 out of 15 seeds sprout your germination rate is 80%).


Planting distances and cross-pollination


Seed-saving techniques and instructions


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