Seed Saving Time: Spinach

Garden spinach (Spinacia oleracea). Image via Wikimedia Commons.By Jill Henderson – Show Me Oz

Spinach is one of the very earliest crops planted and harvested from the garden in spring.  As a member of the Amaranth family (formerly classified as the Chenopodia family), spinach is naturally packed with fiber, protein, and high levels of essential vitamins and minerals.  If you’ve never grown your own spinach or had freshly prepared spinach, you are in for a real treat!  And if you already love spinach and grow it in your garden every year, then why not try saving your own seed?  You’ll not only be rewarded with oodles of eating pleasure, but you’ll save a ton of money, too!

The botanical name of true spinach is Spinacia oleracea.  All varieties of true garden spinach will readily cross-pollinate one another.

With this in mind, it is  important to understand that not all plants that are referred to as “spinach” really are spinach.  Usually that name is used to suggest that the plants resemble or taste like true garden spinach (Spinacia oleracea).  Spinach imposters include orach or mountain spinach (Atriplex hortensis), spinach mustard (Brassica rappa), Malabar spinach (Basella alba), water spinach (Ipomoea aquatica), and New Zealand spinach (Tetragonia tetragonoides).

Because these wanna-be spinaches do not share the same botanical names as true garden spinaches, they can be safely grown in the same garden as true spinach without worry of unwanted cross-pollination.

Male spinach plant. By Rasbak (Own work) [GFDL ( or CC-BY-SA-3.0-2.5-2.0-1.0 (], via Wikimedia CommonsWhen growing spinach for seed, it is important to realize that each individual spinach plant will either be a male or a female.  Male plants produce super fine pollen that can be carried on the wind for long distances and may easily cross with wild varieties and other cultivated varieties being grown near by.

In order to harvest viable seed, there must be at least one male plant for every two or three female plants and they must be growing close enough together so that they can be bunched together when flowering begins.  It is almost impossible to tell male spinach plants from female spinach plants until the flowering stalks emerge, but in most varieties, the males are the first to bolt, followed shortly by the females.

Female spinach plant. By Rasbak (Own work) [GFDL ( or CC-BY-SA-3.0-2.5-2.0-1.0 (], via Wikimedia CommonsPlant spinach in dense blocks, reserving a section exclusively for seed production.  An early, light harvest for eating will not affect seed production, but as soon as plants begin to bolt, stop harvesting for food and start thinning out the males.

Spinach requires up to 6 weeks beyond eating stage to produce flowering stalks, therefore, is best to plant spinach as early as possible in the spring.  In mild winter areas, spinach can be planted in spring or fall.  Plants grown for seed should be spaced at least 8” apart because crowded plants tend to bolt to seed prematurely.

Spinach begins bolting when day lengths reach 12-15 hours.  This can happen very quickly to you must be ready to reduce the possibility of cross-pollination from outside sources.  This is called isolation. Female spinach flowers.  By Rasbak (Own work) [GFDL ( or CC-BY-SA-3.0-2.5-2.0-1.0 (], via Wikimedia Commons

If you are only growing one variety of spinach and do not have close neighbors who are also growing spinach, all  you need to do is thin plants to include one male plant for every four females.

Otherwise, you will need to bag your plants to ensure pure seed.  Do this by loosely tying several stalks together making sure to include several female plants with at least one male.  Enclose all of the flowering parts in a heavy, garden grade paper bag, taking care to block the bottom of the bag with batting to prevent pollen from escaping and insects from entering.

Do not use spun polyester or other fabrics as bagging material because the super-fine pollen of spinach can easily move through even the tightest fabrics.  Shake the stalks daily to distribute pollen inside the bag.  Do this until flowering is complete.

Once the seed pods begin to form and all flowers are faded, remove the bag and allow the plants to mature in the field until the seed pods begin to turn brown.  If most of the pods are turning brown and weather or other issues arise, the plants can be pulled up from the roots and hung upside down in a dry, shady place such as a garage or shed until completely dry.  To prevent losing seeds, enclose seed heads inside a paper grocery bag and tie shut.

Dry spinach seed pods.  Image via Blandria's Backyard Garden - the seeds are fully dry, simply strip the pods from the stems and crush them by walking on them or rubbing them between your palms.  You can also place the pods in a 5-gallon bucket and crush them with a blunt object like the end of a 2×4.  But be gentle when using the latter method, as seeds can be easily damaged.

Now that the seeds are free, it’s time to separate the seeds from the chaff.  The easiest way to do that is to build or buy screens with varying size holes through which the seeds are sifted.  This removes all but the finest chaff.  The rest can be easily winnowed away using two large bowls and a small fan.

Start the winnowing process by laying out a tarp or bed sheet directly in front of your fan.  The tarp will catch any seeds you lose and allows you to see what is being winnowed away and what is being caught, which will help you perfect your method.

Winnowing chaff.Start by setting the fan to it’s lowest setting and adjust the speed as necessary.  Position the bowl with the seeds in it just above the air stream and the empty bowl just below it.   Very slowly, pour the seeds from one bowl into the other.  The wind from the fan will carry the light, dry chaff out and away, while the heavier seeds will fall straight down into the empty bowl below.

Winnowing does take a little practice, but is a lot of fun to do!  And if you lose a few seeds in the process, don’t worry – you’ll still wind up with more seed than you know what to do with!

Happy seed saving!

© 2013 Jill Henderson – feel free to share with a link back to this site.

The Garden Seed Saving Guide by Jill HendersonExcerpted in part from my book:
The Garden Seed Saving Guide

Whether you’re a weekend gardener, homesteader, or serious survivalist, saving seeds is a money saving skill that every green-thumb should to have. An excellent resource for beginners and experienced gardeners alike, The Garden Seed Saving Guide takes you step-by-step through every aspect of saving seeds. If you want to save money, become more self-sufficient and avoid genetically modified food crops, The Garden Seed Saving Guide is for you.  Available in the Show Me Oz Bookstore

Jill Henderson is an artist, author, and the editor of Show Me Oz . Her books, The Healing Power of Kitchen Herbs, The Garden Seed Saving Guide and A Journey of Seasons can be found in the Show Me Oz Bookstore.  Jill’s work has also appeared in The Permaculture Activist, The Essential Herbal, Acres USA, and Llewellyn’s Herbal Almanac.

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3 responses to “Seed Saving Time: Spinach

  1. Spinach is high in oxalates that block mineral absorption, especially calcium. Not for human consumption.

    • Hi Tommy. There are many vegetables and wild edibles that contain oxalic acid – French and garden sorell, rhubarb, chard and beets to name a few. When leaves are eaten raw, oxalic acid does prevent the absorption of calcium and some minerals, but not the calcium or minerals in foods that are consumed along with it, such as cheese or milk, for example. And while large amounts of oxalic acid can be detrimental to health (rhubarb leaves contain high concentrations and are considered toxic) cooking actually destroys oxalic acid, allowing the body to absorb those previously blocked minerals and calcium.

      Spinach is a super healthy green loaded with folic acid, potassium, magnesium, vitamin K, carotenes, vitamin C and lutein, and more. If you are concerned about the minor issue of calcium blocking (which only occurs when you eat the raw leaves and is not a permanent ‘condition’), then by all means, cook your spinach before you eat it! 🙂

  2. Pingback: Happy New Year & Thank You…for Everything! | Show Me Oz

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