Dear Shawna ,

Thank you for contacting the UNH Extension Infoline.

In follow-up to your email inquiry on November 2nd regarding seed storage and cultivation, we have provided some general information that may be helpful.

Although this information is generic and not specific to New Hampshire, it is applicable to the general New England region and other states with similar cold climate.

We are committed to helping you find a solution and are confident that we can provide the right guidance.

Please feel free to reach out with any further questions.

The UNH Extension Infoline Team,

Master Gardener volunteer, Haim.

General information 

To successfully cultivate and store seeds, you must select the right parent plants, harvest at the correct maturity stage, thoroughly dry the seeds, and store them in a cool, dark, and dry environment to maintain viability.

Cultivating and Harvesting

Choose Open-Pollinated (Heirloom) Varieties: Seeds from hybrid plants will not produce true-to-type offspring, often resulting in inferior quality plants. Select open-pollinated or heirloom varieties instead.

Select the Best Plants: Only save seeds from your healthiest, most vigorous, and disease-free plants that exhibit the traits you desire (e.g., best taste, fastest growth).

Prevent Cross-Pollination: To ensure seeds grow "true to type," grow only one variety of a species per season, use physical barriers like bags on flowers, or time plantings so different varieties flower at different times.

Harvest at Full Maturity: Seeds need to be fully mature before harvesting. For dry-fruited plants like beans and peas, let the pods dry and turn brown on the plant until the seeds rattle inside. For fleshy-fruited plants like tomatoes and squash, let the fruit become overripe on the plant before harvesting the seeds.

Process Seeds Appropriately:

Dry Processing: For dry seeds (e.g., lettuce, beans), separate the seeds from the chaff (plant material) by threshing (rubbing or crushing the dried material) and winnowing (using a fan to blow away the lighter chaff).

Wet Processing: For fleshy seeds (e.g., tomatoes, cucumbers), scoop out the seeds and pulp, and often ferment them in a jar with water for 1-3 days to break down the gelatinous coating. Viable seeds will sink to the bottom. Rinse thoroughly afterward.

Drying and Storing

Thoroughly Dry Seeds: This is the most important step to prevent mold and ensure viability. Spread cleaned seeds in a single layer on a non-porous surface like a screen, coffee filter, or ceramic dish in a cool, dry place with good air circulation. Avoid direct sunlight or high heat (over 95°F). Seeds are sufficiently dry when they are brittle and snap or shatter when bent or smashed.

Use Proper Containers: Place completely dry seeds in paper envelopes or bags (which allow them to "breathe") and then store these in an airtight container, such as a glass jar or a sealed plastic box, to keep out moisture and pests. Adding a desiccant packet (like silica gel or powdered milk in a tissue) can help absorb residual moisture.

Store in Ideal Conditions: The enemies of seed viability are heat, light, and moisture. Store containers in a cool, dark, and dry location, such as a dark closet, a dry basement, or a refrigerator. If using a refrigerator or freezer, allow the sealed container to reach room temperature before opening to prevent condensation from forming on the seeds.

Label Everything: Immediately label containers with the plant variety, any relevant notes (color, size, etc.), and the date of harvest.

Test Viability: Before planting season, you can perform a germination test by placing a few seeds on a moist paper towel inside a plastic bag and keeping it in a warm place to see how many sprout. This helps you decide if you need to sow more densely.

Below you can find some useful web links to university extensions for specific information. In addition, Oregon State University provides step-by-step useful information."

https://extension.psu.edu/seed-saving-basics#:~:text=Drying%20and%20Storing,edible%20and%20ornamental%20garden%20crops.

https://yardandgarden.extension.iastate.edu/how-to/how-harvest-and-store-seeds#:~:text=store%20the%20seeds.-,Storing%20Seeds,warm%20and%20damages%20the%20seeds.

https://extension.umn.edu/planting-and-growing-guides/saving-vegetable-seeds

https://extension.oregonstate.edu/catalog/em-9663-step-step-guide-saving-seeds