free to download, an expert guide to seed-saving

Paper bags of seed drying in the mudroom.AROUND NOW, THE HOOKS on my mudroom walls offer no space for coats (though the weather hints I’ll be needing mine). Too many paper shopping bags are hanging there instead (photo above), one after another with faded, upside-down plants inside, meant to let go of their increasingly dry seed.  That’s my primitive tactic, but there are better ways to save seed, and the Organic Seed Alliance shares them—from which variety you grow with eventual saving in mind, to maintaining that crop in the garden, to drying and even storing it–in a free, 30-page book-like pdf download loaded with both the botanical science and sensible tips, too.  

roguing, and isolation distances

YES, IN THE BEST-CASE SCENARIO, preparing to save seeds starts with decisions about what variety to plant in the first place, and rouging out weak and then “off types” that don’t measure up, or conform to the desired traits of that particular tomato or squash or zinnia. Inferior or atypical? Out you go!

It’s a process that is repeated throughout the life cycle. For instance, you might pull the lettuce seedlings that are slowest to germinate from your row or cellpack; later pull and eat any with off-type foliage, and perhaps even rogue a third time if some individuals prove more inclined toward disease than others. Only let the best and brightest go to seed and provide the genetics for next year.

Organic Seed Alliance seed-saving guide Want to guard against inadvertent cross-pollination? A chart in the OSA’s guide clarifies what crops are vulnerable (and what close cousins they can cross with—such as carrots with wild Queen Anne’s lace, or that many brassicas, such as Brussels sprouts and kale and cabbage and broccoli, among themselves). Crop-by-crop “isolation distances” for both home gardening and commercial seed production are specified, to insure that your seed stays pure.

Both “dry-seeded” and “wet-seeded” crops are covered (the former are formed in pods, like beans or lettuce, the latter inside fleshy fruits, like tomatoes or peppers). How to test that your seed is dry enough to store successfully, and the pros and cons of different containers and places for storage is also tackled in this extensive manual.

tips for saving tomato and squash seed

AGAIN: Because this is a guide for seed farmers and gardeners alike, you’ll get lots of the “why” and “how”—the science of pollination and sexual reproduction, for instance—but also simple “how-to’s.”

For instance:  “If you want prime tomato seed, harvest the fruits when they are starting to soften, but before they show signs of decay.”

And: Don’t rush those squash seeds!

“The seeds of summer squash are still very immature when the fruit is edible,” the guide explains. “Leave edible summer squash on the vine for around 6 weeks. Wait for fruits to become very large and hard (you should not be able to dent the flesh with your thumbnail) and for the stem at the point of attachment to the fruit to dry up. Once the squash reaches this stage, you have options for harvest; a) if the fruits are not at risk for disease or damage, allow the squash to remain on the vine until right before the first hard frost, or b) if the fruits are at risk for disease or damage, harvest the fruits right away and store at 65-75F (18-24C) for a few weeks before extracting the seed.”

heirloom squash

the organic seed alliance

THROUGH RESEARCH, education and advocacy, the non-profit Organic Seed Alliance—currently celebrating its 10th anniversary–“advances the ethical development and stewardship of the genetic resources of agricultural seed,” working with organic farmers and other seed professionals. It  fosters regional seed independence through participatory breeding projects with farmers, aiming for “farmer-centric seed systems” that focus on selecting for germplasm well-adapted to each particular area of the nation. You may recall my Q&A on growing carrots with the OSA’s former senior scientist, Dr. John Navazio.


  1. Ms. Tweetley says:

    Another resource on seed saving and breeding that was just published is Plant Breeding for the Home Gardener (Timber Press, 2013) by Joseph Tychonievich. I found it fascinating and encouraging. Thanks for this download from Organic Seed Alliance.

  2. Susan says:

    My grandmother showed me how to save seeds. I haven’t bought a marigold in many years. I also keep pumpkin and squash seeds.

  3. Mike Hammond says:

    Thanks for the Seed-saving Guide. I expect I’ll be putting it to good use, as I’m always getting chances to save seeds, Wow, now I’ll actually be able to do something with ’em!

    1. margaret says:

      You are welcome, Mike. OSA is a great organization, doing such important work with farmers to insure that the future includes organically produced seed adapted to every region. Enjoy the guide.

  4. Jen says:

    Thank you so much for the seed saving guide! I currently have some red cosmos in brown paper bags, but, recently, I have been using the Halloween “Loot” bags from my kids birthday party leftovers! They are like little ziplock bags with fun spiders and such on them. I know I will get a kick out of them come spring time. I have lots of seeds and of course, big plans for the garden next year.

  5. Mysterious Gardener says:

    Thanks for the link to the guide, Margaret. Organisations like OSA are invaluable; great that you’re promoting them!

  6. Louis says:

    Thanks for the OSA guide site. I’m a beginning farmer with a great deal of homework to do. I look forward to it. I grew up post WWll in an ethnic neighborhood. Very few lawns but the vegetable gardens were surrounded by flowers. I remember as a young man, the early morning walks in the summer with the sound of French and Polish being spoken and the smell of freshly baked breads and pastries. People in this mill town were proud of the fact that if they could make it, or grow it, they would. There was very little waste back then. So as I sip my water from a reclaimed pickle jar, I begin my journey.

    1. margaret says:

      Hi, Louis. The OSA is a great resource — and there are many links to related organizations to follow from their site. Enjoy, and thanks for saying hello.

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