Do you save seeds? These days, more and more gardeners are interested in keeping seeds from the plants in their garden, but it’s a process that can be intimidating. For this week’s episode, I invited Executive Director of the Rocky Mountain Seed Alliance and master seed saver, Bill McDorman, to share his expertise for anyone interested in saving seeds.
Bill has saved countless species. In fact, he owned and ran his own mail-order seed company for nearly 30 years. He also wrote a book – Basic Seed Saving – and created a six day hands-on class for gardeners looking to take a deep dive into this aspect of edible plants.
He refers to seeds as the most magical living thing you’ll ever put in your hand. They are living, hibernating embryos – which can remain dormant for decades before springing to life in the garden.
Passionate about seed diversity and the opportunity that we, as home gardeners, have to contribute to development of future varieties; Bill could speak for hours on the subject, but we squeezed as much information into this hour-long format as we possibly could.
Why Save Seeds
Seed saving does take a little effort and time, but it is so worthwhile for gardeners of all experience levels. Yes – there are some great, reliable seed companies to order from, and I’ve featured a couple of those in previous episodes.
Here’s the thing: When you find a variety that works for you, saving seeds from that variety will help you replicate success season after season. Why? Plants are sensitive to the growing conditions unique to each individual garden – much more so than you might realize. What works well in your space, might struggle in your neighbor’s garden.
There are so many variables at play – including your unique microclimate, the microbial health of your garden soil, and exposure to chemicals or other damaging conditions.
You could order more seeds of a variety you know works for you, but you might end up with a miss-marked packet or one infected with a seed-borne disease pathogen. It happens to the best of us. In spite of good faith efforts by seed companies, these issues do occur.
That’s not to say you shouldn’t order seeds. I do every year! It is, however, a good argument for saving some of the seeds from a plant which performs really well in your garden. After all, there just might be something unique to the DNA of that particular plant, which gave it a slight leg up and which others of the same variety won’t have.
It has also been shown that plants adapt to their conditions over time. So, as the seed-produced descendants of the plants from your previous season continue to mature and produce in your soil, they will be more adapted to it than plants from purchased seed.
Plus – saving seed from successful plants gives you the opportunity to carry the best of your harvest into seasons to come – or to discover something entirely new.
You might just find yourself with a plant that’s not like anything else before it. How? Cross-pollination (which we’ll cover more in a minute) can sometimes create a DNA cocktail that produces magic.
I’ve already mentioned that plants will adapt to your particular garden, and it’s that ability which also means that seed from plants grown in your region may be better-equipped to perform well for you.
If I purchase seed from a catalog company whose seeds were produced from plants grown in California (which I often do), does that mean they won’t perform in my hot and humid Atlanta-area garden? No, but those seeds may be a little less likely to thrive than the same variety seeds produced from a plant which grew in the southeastern U.S.
There is no right or wrong answer here – just opportunities to explore subtle differences and experiment.
As a smart gardener, you should always pay attention to the hardiness zone referenced for a seed variety. Having seeds appropriate for your zone is key, but consider just how large each zone is. Within each vast hardiness zone are thousands of what Bill calls “niche climates.” Your garden, your city, your state – these are all examples of niche climates which will have a direct impact on plant growth.
Here’s another example: In Part One of my conversation with Charles Dowding a couple of weeks ago, Charles described one of his garden experiments. He’s been growing fava beans in the same spot for five seasons. He’s testing the theory that crop rotation is necessary to prevent disease and keep soil healthy. Well, this fifth year of fava beans is his best yet, but here’s the thing, he attributes that – in part – to the fact that he’s replanting from seeds from the previous year’s fava bean crop.
In other words, the descendant plants of each successive fava bean crop are becoming more and more accustomed to Charles’ unique soil. They are adapting to his garden’s conditions, including the species of microbes present in his soil.
The theory goes that this improves the fava bean plant’s ability to fight off any soil-borne pathogens and to better take advantage of the nutrient and disease-fighting powers of the beneficial microorganisms. If he purchased fava bean seeds, they may not produce a plant as readily able to thrive in his soil. Sounds like an opportunity for another experiment, right?
A Little History Before We Get to the Nitty Gritty
Have you ever thought about the fact that everything we grow in our garden was once either a wild plant or the result of intentional or accidental cross-breeding? Bill used the example of romaine lettuce. Before it was the leafy crop so many of us love to grow and eat today, it was probably the same species as wild, prickly lettuce. You can still find this prickly lettuce in the wild or growing as a weed, but you probably won’t want to eat any of it.
The tasty qualities in modern-day romaine lettuce are the result of seeds which were saved from wild plants that were naturally less bitter. Those seeds were grown out, and the least bitter of the next generation produced more seed, which was also saved and grown again.
Saving seed from generation after generation of the plants which stand out from their “siblings” – allows the naturally-occurring DNA “flukes” (which caused a desirable trait) to stabilize.
Nowadays, there are scientific laboratories which examine molecular structure and breed plant varieties under careful conditions in order to encourage desirable traits – like disease resistance or color. However, it was just everyday people – saving seeds of the plants they liked – who contributed to the development of many of the crops we enjoy today.
Gregor Mendel was the forefather of modern-day plant breeding. Bill explains that – before Gregor’s work in the 1800s – most plant breeding and varietal development was done, primarily, by indigenous women who saved seeds to improve a wild plant. That kind of history is just one of the many things I love about gardening, and that I love to think about while I’m out there tending to my plants.
One troubling plant fact is that 90% of the varieties which were being grown at the turn of the 20th century – in 1900 – are no longer available. They were lost in the popularity of seed commercialization and production for larger agricultural operations.
Fortunately, heirloom varieties of all sorts of plants have really made a comeback. The Seed Savers Exchange played a big role in that resurgence. During just the past two decades, they discovered around 25,000 varieties of seed that the horticultural world had thought was lost.
My friend, Craig LeHoullier, is another one to thank when it comes to heirloom tomatoes. He has personally brought back many popular heirloom varieties from the brink of extinction. It takes patience and hard work, but Craig and the folks at Seed Savers Exchange consider it a labor of love.
Heirloom vs. Hybrid
So, what constitutes an heirloom variety anyway? That’s an important definition to understand when it comes to saving seeds.
Heirloom plants are varieties that have been handed down – as seeds – for 50 years or more through farmers and gardeners. They were typically saved and passed on because the plant had favorable traits or, even, just for sentimental reasons.
Heirloom plants usually have an interesting history, but what matters most when it comes to seed saving is that the seeds from heirloom plants contain stable DNA. That means that the plants and crop produced from heirloom seeds will feature the same traits as the parent plant.
Hybrid plants, on the other hand, are the creation of intentionally cross-bred varieties. I like to use Sungold tomatoes as an example. Two different varieties are cross-bred under the controlled environment to produce seed which, in turn, produces the Sungold variety.
Seeds from a hybrid won’t produce true seed – a second-generation plant with identical characteristics. So if I save seeds from my Sungold fruit, the DNA in those seeds is unstable. The plants those seeds produce will be a hodgepodge kaleidoscope of traits which existed in the Sungold’s parent plants.
Now, it is possible for some heirloom varieties to become cross-pollinated with another variety. That would mean that the seed produced from that pollination will carry DNA from two different varieties. What will grow from that seed? Bill is hoping more gardeners will be open to embracing the mystery and beautiful possibilities of that scenario.
Where to Start
There are plenty of books out there explaining how to save seeds. The problem tends to be that you need other books to help you understand how to read the seed saving books. Many resources out there provide information in a format that confuses any home gardener who doesn’t have a solid understanding of other horticultural information, like botanical Latin.
The reality is that there are a lot of seed varieties which are really easy to save. One of the first examples Bill gives is the tomato.
Tomatoes are self-pollinating. That means their flowers don’t need a neighboring tomato plant in order to pollinate. The flower of a tomato, will receive its own pollen before a neighboring plant’s pollen makes its way into the flower.
Is it possible for a tomato variety to cross-pollinate with another variety in your garden – or your neighbor’s garden? Yes, but there is a very low probability of that happening. So, you can feel confident that the seeds of your heirloom tomato will produce the same plant variety.
Peppers, peas, beans, and lettuce are just a few more examples of plants which have a self-pollinating “perfect flower” – like the tomato. If you’re wondering about your favorite plant, just do a little research online. Educational websites – like college institutions – which have the extension .edu (as opposed to .com) are reliable resources of information.
If your research determines that the plant you are interested in has a “perfect flower” – a flower which contains both male and female parts – you’ll know whether or not the plant is self-pollinating.
Another reason tomatoes are so easy when it comes to saving seeds is that the plant will mature, develop fruit and set seed within a single season. Not all plants have such a rapid life cycle, but most of the plants common in a home vegetable garden do. That makes those plants a great place to start.
What to Save
So, let’s say you’re growing a few plants of the same variety. How do you choose which plant – or which fruit from that plant – to save the seeds from? Some gardeners really feel anxiety about this – the pressure to make the right decision! The truth is, there is no wrong decision. You could choose any one of the fruits from your tomato plant, for example.
That said, you could also choose to save seeds from one particular fruit because it just seemed to taste a little better. Do you notice that one of your three Black Krim tomato plants is a little healthier than the other two? Saving seeds from fruit of the healthier plant might just capture a subtle difference in DNA that will produce slightly healthier plants next season.
As much as some of us might prefer precise science with a paint-by-numbers-so-you-can’t-go-wrong approach, we’re dealing with nature here, and nature can be an unpredictable business.
So, just try something. See what happens, and take a few notes. I’m betting you’ll be pleasantly surprised – and curious to try something slightly different next season.
It probably goes without saying that, if you find a fruit or a plant that’s malformed or shows signs of disease, look for a better option. What if you don’t have other options? Well, don’t be afraid to give it a try with what you have. Regardless of the outcome, you will have learned something and enjoyed a new experience.
When to Save
The best time to harvest seeds really depends on the plant. Seeds in a pod, like peas and beans, will be most viable once the pod has become dry and brittle. That can be tricky, because the dry pods often split. It’s nature’s way of scattering seeds for next year’s plants. So, it’s a good idea to keep an eye on things once pods start to dry, or look for creative solutions to capture the seeds as they pop out of the pods.
Seeds from many fleshy crops – like tomatoes and peppers – are ready as soon as the plant is ripe. So if you bite into a pepper that knocks your socks off, save those seeds.
Some varieties of seed which need to mature on the vine long after the fruit or vegetable might be considered ripe. Cucumber seeds are one example.
Cucumbers which remain on the vine can become twice the size of what would be considered a ripe fruit. Many varieties will eventually develop a hard, orange shell – like a squash. It’s this larger, squash-type stage at which cucumber seeds are fully mature and most viable.
A crop which has passed its prime on the vine shouldn’t reach the point of rotting. If it’s overripe, open it up and observe the seeds. If they don’t look rotted, and they still have a firmness to them, they could still be viable – and certainly worth saving if they are your best option.
Whatever you are growing, don’t be afraid to experiment with seed maturity. Try harvesting the seed at various phases of ripeness and make notes. Then when you plant the seeds, observe the results and note that too. Those lessons will help you achieve better and better results over time.
If the seeds you collect need to be washed – like tomato or melon seeds which are encased in sticky or slimy materials – be sure to dry them thoroughly. Moisture is the enemy in the seed saving world.
In the case of tiny seeds or dry seeds – like lettuce or grains – don’t wash them in water. Instead, remove the chaff – other plant debris – by sifting or blowing across the material. I demonstrated this in an episode of my show, Growing a Greener World®. It’s easy to do, but watching the process is helpful.
For many vegetable varieties (squash, melon and corn – just to name a few), leaving one or two vegetables on the vine as long as possible for seed harvest is ideal – but not always possible. Sometimes, Mother Nature has other ideas and hits you with a cold snap. Those of us who live in humid areas are at risk of overripe crop rotting in the field.
In those instances, you can opt to try pulling and hanging the entire plant upside down in a cool, dry location. The remaining energy in the vine may continue to feed the seed what it needs to mature. Storing unripened fruits or vegetables to allow more time for the seed to mature is called “curing” the seed.
Another method of curing is to harvest the crop and store it indoors – also in a dark, cool and dry environment for several days. The seeds might still develop. In any case, what’s the harm in trying?
When storing individual fruits or vegetables, it’s important that they don’t touch each other. Allow air space between each one. Expect that one or two will, inevitably, develop a fungus. The air space between them decreases that likelihood, and it also prevents the fungus from spreading as quickly. As soon as you see fungus on any of your stored crop, get rid of it ASAP.
How long to cure depends on a number of variables – like how ripe it was when you picked it, how ideal your storage conditions are, and what type of crop it is. Bill says that 2-4 weeks is, generally, a good rule of thumb; but don’t get bogged down by the details. Harvest the seeds whenever you feel it’s a good time.
You won’t know how viable the seeds are until you test their germination rate or put them into soil, but all you need is one successful seed.
Just remember that, when it comes to seed saving, it never hurts to try. Take that cucumber example again. Ideally, those need to remain on the vine long after ripening for seed maturity, but if Bill takes a bite out of a cucumber he has harvested ripe to eat – and loves the taste of that particular cucumber – he will save the immature seeds.
He may not have as much germination success with that group of seeds, but all he needs is one success to grow another cucumber plant.
There are a number of ways to store seeds once they have been harvested and cleaned. The main storage concern is to keep the seeds dry, cool and out of the light; so that they will remain viable longer.
Glass is a better storage option than plastic for blocking moisture. Just be sure to store the glass out of the light. Envelopes are another good option. They block light and don’t trap latent moisture. No matter what you use, don’t store them in a room warmer than 80 degrees Fahrenheit.
The cooler you keep them, the longer seeds will remain viable. They can be stored in the refrigerator or the freezer, but it’s best to stick with a glass container in that environment, rather than an envelope. Canning jars are a good option.
Bill recommends packaging seeds on a day with low humidity if you can. It’s not a necessity, but it might prolong the seed viability a bit more.
So, how do you test the viability – or germination rate – of the seeds you’ve saved? It is so easy, and it’s the same process for any type of seed from anywhere.
Pick ten seeds from your group and place them in a row on a paper towel. Wet the paper, and roll it up. Next, keep it somewhere at room temperature and where it will be easy for you to keep moist. Seed germination periods vary according to type, but the specific period for the variety you are working with is easy to find online.
After the appropriate germination period has passed (oftentimes, it’s about one week), unroll the paper towel to see how many of the ten have sprouted. If it’s 2 seeds out of the 10, the seeds you’ve saved have a 20% germination rate. If it’s 7 out of 10, that’s a 70% germination rate.
Bill tests 100 seeds. He places 10 rows of 10 seeds in the paper towel to test germination. This provides a more accurate percentage, but if you don’t have a lot of seeds, all you need to test germination is one row of 10.
Is it necessary to test germination? No, but if you’re not sure whether or not the seeds are worth planting, the test can help you to make that determination.
Here’s a pro tip: If you store any seeds in the refrigerator or freezer, don’t open the lid of the container immediately. Allow it to slowly warm up to room temperature. If you open it while it’s still cool, humidity can condense in the container. That can damage the seeds and lower your germination rate.
How long can seeds be stored and still be viable? That is the age-old question. The answer depends on all sorts of variables. How mature are the seeds when they are harvested? How well are they cleaned and prepared for storage? How ideal are storage conditions? What variety are the seeds?
There’s a popular chart that lists varieties and the length of time those seeds can remain in storage. Bill had long been fascinated to find out who created the chart. It’s decades-old but still referenced by many reliable resources.
It turns out that the chart originates from a garden newsletter publication from 1889. It was compiled by an amateur gardener – a backyard gardener – who grew and saved seeds in the southeastern U.S. – the very humid southeastern U.S.
The lesson here is that the information provided in viability charts is a good starting point, but it isn’t gospel. That gardener’s humid environment – in combination with the fact that refrigeration didn’t exist at that time – means that seeds have the ability to remain viable for much longer than the timelines he had experienced and recorded.
Life span all depends on the variables you are dealing with.
One question I get asked all the time is how to prevent cross-pollination of plants, to ensure that the seeds will be true to the parent plant. We’ve already addressed those plants with self-pollinating flowers. So, bear in mind that cross-pollination really isn’t a concern for those types of plants.
When it comes to the plants which aren’t self-pollinating, Bill stresses that cross-pollination is not necessarily a bad idea. By allowing nature to do its thing, the cross-pollinated seed will provide you with a plant that no one else has, and it just might be spectacular.
The Waltham butternut squash is the most popular of all butternut squash varieties. Well, we wouldn’t have the Waltham were it not for an accidental cross-pollination that took place in the Pennsylvania backyard garden of an insurance salesman in the 1960s.
He recognized that the crop was unique and better than any variety he’d tried. So, he brought some of the seeds to his local Extension agent. At the time, Extension agents were actively involved in trialing plants. This particular Pennsylvania Extension agent grew out the seeds in successive generations to stabilize the DNA of the accidental cross, and voila – Walthams now grace many of our modern-day dinner tables.
So, who knows what you might wind up with by allowing cross-pollination to occur.
All that said, there are steps for preventing cross-pollination – should that be your goal. Remember that a pollinated flower can’t accept more pollen. You can use that knowledge to your advantage in a few different ways.
The flowers of plants like squash, melon and corn tend to produce pollen in the morning, so you could pollinate a few flowers by hand early in the day to get ahead of pollen from plant neighbors. After hand pollinating, gently close the flower with a clothespin for a few hours to allow the pollination process to complete. Once that time has passed, the flower won’t be able to take on pollen from other plants.
You could also plan ahead a bit. Plant your crops a little earlier than your neighbors – or in stages within your own garden. The plants will mature and the flowers will be pollinating at different times than neighboring plants, which eliminates the possibility of cross-pollination. Bill planted three varieties of corn a month apart to ensure that the tassels of the first variety dried up by the time the tassels of the second variety matured.
If you’re really serious about it, there are pollination cages available to buy, but you can make your own. Using PVC piping, create a hoop and place reemay or floating row cover over the plant onto the hoops. Pollen from other plants won’t be able to pass through the fabric.
Unfortunately, covering the plant with a cage also keeps out the pollinating insects, but you could carefully place pollinators into the cage for a day.
If you aren’t growing in close proximity to other gardeners, preventing cross-pollination can be as easy as growing just one variety during a season. If you only have one type of melon in your garden and no nearby gardens, there’s no risk of cross-pollination.
The bottom line in all of this really is that there are many more ways to successfully save seeds than there are pitfalls to the process. Have fun with it. Experiment.
I really recommend that, if you haven’t done so already, be sure to listen to my conversation with Bill by scrolling to the top of the page and clicking the Play icon in the green bar under the page title. For one thing, you’ll hear Bill share a few more examples from his seed saving experiences and world travels.
Most importantly, I really believe that our conversation will stir excitement to embrace these new experiences – even if they feel clumsy or a little vague to you. You don’t need to have all the answers. You simply need to get started by giving it a try. I’d love to hear about your seed saving experiences too! Share the lessons you have learned in the comments below.
Links & Resources
joegardener Online Academy: Master Pests, Diseases and Weeds – Just $47 for lifetime access! Watch for my new course on seed starting coming soon!
Seed to Seed: Seed Saving and Growing Techniques for Vegetable Gardeners, by Suzanne Ashworth
The Seed Garden: The Art and Practice of Seed Saving, by Lee Buttala, Shanyn Siegel, Jared Zystro, and Micaela Colley