Harvesting and Storing Seeds

As the growing season winds down, it’s good to reflect on what you learned this year and what you would like to grow in the future. If you have a variety that you enjoyed and would like to plant again, now is the perfect time to harvest and store seeds for next year. Since store bought seeds can be expensive, keeping seeds from this year’s harvest is a great way to save money. Seed saving is fun, and the seeds can last a long time if stored properly!

Before starting, you need to do a quick Google search to make sure that the plant you are harvesting seeds from is an open-pollinated variety. This means that the plant had two parents of the same variety as itself, and that its “children” will be genetically identical to it. In contrast, hybrid plants are bred from parents of two different varieties. While hybrid plants have many growing advantages, one disadvantage is that they produce seeds with unpredictable genetics. In other words, you won’t be able to guarantee that your future vegetables will be identical in flavor or appearance to your current one(s).

Heirloom varieties are always open-pollinated.

Even if you are saving seeds from an open-pollinated variety, some vegetable seeds are easier to save than others. This is because plants can experience something called cross pollination. Cross pollination is when the pollen of one variety of a plant gets onto the flower of another variety, resulting in seeds that have mixed genetics. There isn’t anything wrong with cross-pollinated seeds in principle - they should still sprout and grow. But they’re not “purebred” - they won’t be the same as the parent plant. So, if you want your future plants to be identical to your current one(s), you need to avoid harvesting cross-pollinated seeds.

Now, if you only grew one variety of each kind of plant, and there weren’t any other varieties of that same plant growing nearby, you don’t need to worry about getting cross-pollinated seeds. For example, if you only grew Straight Eight cucumbers, and none of your neighbors garden, your seeds will be Straight Eights. However, say your next door neighbor decided to grow Armenian cucumbers. Then it is possible that some bees carried pollen between the two varieties and cross-pollinated them. 

Cross pollination. Image by Teohalfen (cropped).

​Some vegetables are very unlikely to become cross-pollinated even if multiple varieties were grown together. These are considered “super easy” to save seeds from and include tomatoes, peppers, lettuce, beans, and peas. On the other hand, vegetables from the cucurbit family (melons, cucumbers, squash) and the brassica family (cabbage, kale, brussel sprouts, cauliflower) are very prone to cross-pollination.

How you harvest the seeds will depend on the type of plant the seeds come from. Some vegetables grow seeds inside the fruit you harvest, others grow seeds in separate pods, and some do both. You can use this guide to check the best way to harvest seeds from specific vegetables. 

​Perhaps the easiest seeds to harvest are beans and peas. While the plant is growing, leave some of the pods to fully mature and then dry out with the rest of the plant. Then snip the pods and let them dry indoors in a dark place for a few weeks. Afterwards, you can remove the dried peas and beans and place them into your storage container. For other vegetables, you will need to scoop the seeds out from inside the fruit and spread them out on a plate or paper towel to dry. Some seeds, such as tomato and cucumber seeds, are best harvested through a process called fermentation and then allowed to dry. Lastly, some vegetables such as lettuce and radishes need to “bolt”, or grow seed heads, in order for you to harvest their seeds.

Lettuce is usually eaten before it bolts, but if left alone it will develop seed heads, especially if exposed to hot weather. Image by Dwight Sipler (unmodified).

Regardless of the vegetable, seeds must be stored in specific conditions to maximize their lifespan. Some of the things that kill seeds are heat, light, germs, and moisture. Heat and light can make a seed sprout prematurely or reduce its vigor (sprouting power). Bacteria and fungi can take over your seeds if exposed to moisture. Be sure to wash your hands before handling seeds and place them only on clean surfaces. 

One of the best ways to store seeds is to package them in small paper envelopes. Label each envelope carefully with the vegetable name, variety, origin, and date. The envelopes can then be placed together in an airtight container. To help keep your seeds dry, you can put a silica packet (often found in shoe boxes) in the container as well; silica is a natural and non-toxic substance that absorbs excess moisture from the air. Alternatively, you can store your seeds directly in baby food jars or small tupperware. Keep the container(s) in a cool, dry, and dark place, such as a closet.

Mason jars make good seed storage containers.

If stored properly, most seeds should remain viable (able to sprout) for several years. Some seeds have shorter lifespans than others, though. You can use this chart to check how long seeds will last, but for best results, use your saved seeds within one year.

Happy seed saving!