This is just a small “FAQ” type posting on the basics of saving seeds from your own garden. While some seeds can be fairly exotic in how they ought to be handled (including such things as exposing them to smoke to get germination, or the need to be “scarified” or scratched as though they had passed through the gizzard of a bird) for most common garden seeds, it’s pretty simple.
1) let the plant mature (this may be far longer than for an edible harvest).
2) Remove the seeds (varies by type of plant as to “how”.)
3) Clean them a bit (this, too, can vary some. For some plants, letting the seeds ferment is beneficial).
4) Dry the seeds.
5) Pack them, preferably in a water and air proof way.
6) Keep from heat, light, air, and moisture. (A jar in the freezer works very well).
Starting At The End
Why start with #5 and #6?
Because you could always just buy some seeds that have already been through steps 1 – 5 and store them.
Even though I save a lot of seeds, I still end up “buying some” as they are interesting to me. One example is that Walgreen’s Drug Store has seeds. At the end of the season, they “dump them”. Why they think that folks only have a garden in July in California is beyond me, but they act as though this is Alaska or North Dakota. So there is often a “Really Cheap Seeds” clearance sale. I got a large batch for 10 Cents per packet. Yes, they are the “left overs” and not very exciting types. OTOH, I can get a cheap supply of seeds for things like “longevity in fridge vs freezer” germination trials, for having a large area seeded, that will be mowed down by the bunnies in one happy day and never expected to mature, for planting out “way early” and if they don’t make it, no big loss.
In 2009 I got this set of 43 seed packets for $4.30 in an end of season sale. That’s enough seeds to plant one very large garden. For archival purposes I could just as easily have gotten 40 different rare or endangered varieties of heirloom seeds.
Now there is just no way on this earth that I’m going to be planting all those Carrots in one year. Just not going to happen. So how could I save these seeds in a way that lets them stay viable for several years?
Here are all those seed packages stacked inside one glass quart sized mayonnaise jar. Just stick that in the fridge or freezer and it will keep for years. (How many years varies with the type of seed and temperature stability).
Sidebar on Bean Weevils: One summer I had way too many Scarlet Runner beans, so saved a batch in a jar in the fridge. Next spring I opened it to find a bunch of perforated beans, and some dead bean weevils. This was the time I learned about bean weevils… The eggs of these guys are laid into the bean pod on / in the bean. If left in the fridge or at room temperature, they hatch and destroy the beans. However, they die if frozen. I now process all my bean seeds with at least 2 weeks in the freezer, even if they will spend most of their time in a fridge instead. This ‘freeze cycle’ may kill other pest eggs too. So if you have “issues” in your local environment, try a freeze cycle on the seeds.
Sadly, most mayo is now packaged in plastic “jars”, so you will need to “move on” to fruit, vegetable, or sauce jars. Just pick one that is about the same height as the seed packets and has a nice lid. I find sauerkraut jars have a nice portly shape to them and work well ;-)
Why does this work?
Well, the plant is dormant. It is waiting for the “signs of spring” to wake it up. Those are spring showers and rain, warming temperatures, and temperature cycling in the sun. Keep those out, the plant just waits. As long as things are cold and dry, it’s just taking a long winter hibernation.
But life can not live forever in a bottle. For one thing, oxygen in the air is damaging to the cells. Packing in an air proof jar like glass limits this oxidative damage to the air in the jar. As most seeds have some anti-oxidant in them, this extends the life of the anti-oxidant. Packing the jar fully also reduces the oxygen load the seed must face.
When it is time to use some seeds, take the jar from the fridge or freezer and put it in a dark spot to warm. If you set it in a sunny spot, the “little greenhouse” of glass warms too much and can damage the seeds. Just be patient. If you open it rapidly, moisture from the air will condense on the cold seed packages. Raising that humidity is not a good thing.
For ideal keeping, you would have a “deep freeze” that does not “cycle” to a warm phase for automatic defrosting like most refrigerator freezers do these days. If not, it’s still OK. The glass has good thermal inertia and tends to keep the seeds frozen even through a ‘defrost cycle’.
Onion seeds are the shortest lived. Typically good for only one year at room temperatures. Others, especially large seeds like beans and corn, may keep 3 or 4 years even at room temperatures. Packed this way, I’ve used lentil and mung bean seeds up to 16 years later (and they will likely go far longer, that’s just all the time I could wait…) while I’ve had onion seeds sprout after 4 years (and maybe more as I’m still waiting).
A general rule of thumb is that “large seeds keep longer”. Within that guidance, different species have different keeping times.
That’s the basic system. Pretty simple.
Some seeds never dry out (or if they do, they die). These are called “recalcitrant seeds” and are typically found in things like Fruit Trees where it makes fruit over many years so any individual seed doesn’t need to survive 3 or 4 years for favorable growing (an annual might need to “hang tough” a few years waiting for the right conditions to grow again, but doing it as a seed.)
So things like oranges, apples, avocado; they can not be stored in this way.
has some very good information on seed storage in general, but also on recalcitrant seeds. While it is unlikely folks would need to store such seeds for a garden, here is an example of what’s involved:
Recalcitrant seeds include a number of large seeds that cannot withstand appreciable drying without injury; it is of interest that the overwhelming majority of recalcitrant species listed by King and Roberts (1979) are woody. Temperate species such as Quercus and Castanea are commonly stored moist only for short periods over winter. Reduction of storage temperature to near freezing will prolong longevity. Bonner (1973 a) found that it was possible to store acorns of Quercus falcata for 30 months and still obtain over 90 % germination at the end of the period, provided that temperature was maintained at 3 ° C and MC between 33 % (initial) and 37 % (final). A lower MC or a higher temperature (8° C) both reduced germination. For Quercus robur MC should be maintained above 40 % (Holmes and Buszewicz 1956, Suszka and Tylkowski 1980). Recent research in Poland has demonstrated good results from storing this species at >40 % MC in air-dry peat or air-dry sawdust in milk cans at -1° C. It is important to allow free entry of oxygen and this is ensured by inserting several strips of cardboard at intervals between the lid and the edge of the can. In these conditions germination after 3 winters was in the range of 38 – 75 % and after 5 winters was still about 12 % (Suszka and Tylkowski 1980). Temperatures below -5° C killed all the acorns, while a temperature of +1° C encouraged excessive pregermination (60 – 75 % after 3 winters, with radicles up to 25 cm long, compared with 12 % and radicles <0.5 cm long at -1°C). There may be possibilities of storing seeds after emergence of radicles (see p. 152). Recent research in Poland (Suszka and Tylkowski 1982) has indicated that best results are obtained with the recalcitrant Acer saccharinum by maintaining MC at the same percentage (50–52%) as when the seeds were freshly collected. For A. pseudoplatanus in the UK a minimum MC of 35 % is recommended (Gordon and Rowe 1982), while in Poland an MC of 24–32% and a temperature of -3°C have proved suitable to store samaras over three winters (Suszka 1978a).
So you need to keep oxygen going to these kinds of seeds, and not let them dry out too much, while assuring they continue to think it’s just a very long winter…
I’ve found it is very easy to dry seeds simply by putting them on a paper towel, on a paper plate, on top of the fridge. There is generally a slightly warm and dry environment there that is often undisturbed for weeks (as I’m the only one in the house who is tall enough to see up there ;-)
I’ve sometimes just dumped them directly on a china plate and that works fine too. Just make sure they are spread out enough for water to easily evaporate. For seeds, like corn or beans, that may have largely dried in the pod or husk, I’ll sometimes skip any added “drying time”. As added air and warm time shortens life for a seed, I will sometimes just put them in the freezer. If they seem “not fully dry” I may use refrigerator dessication instead. If you are “really into it”, putting a packet of “silica gel dessicant” into the seed jar will ensure drying. I’ve never needed to do that.
After a few weeks, when they are clearly dry to the touch, they are usually about 10%-20% moisture. Still a bit high for optimal storage, but it has worked fine for me for most things. If you want added drying, everyone tends to have a desiccating environment close to hand. The refrigerator. These are designed to condense the water out of the air and send it away from the cold air, that is returned to the box. I’ve not measured it, but I suspect you can get down to the 10% or less range with simply setting a dish of seeds in the fridge, uncovered. Sometimes I use a jar with no lid (or a loose lid or even a paper towel under a canning “ring”); other times I used a “Tupperware” tub with the lid not fully seated.
At times, I’ll package the seeds in paper “coin envelopes” and place these in an open tub or jar in the refrigerator for a few weeks to ‘dry down’ further than the top of the fridge method. I only do this with seeds that I really want to keep for as long as possible.
Then the coin envelopes (each marked with variety, date, special notes) go into a jar, and into the freezer.
Steps 1, 2 and 3
These vary somewhat by plant.
For “green beans” you need to let some “run to seed” and hang on the plant until the pods are dry. Similarly for peas and corn. Generally speaking, nature knows what to do and you just need to not rush it. For some plants, like squash, the seeds expect to keep on maturing inside the squash (that’s what it is for…). So after the plant has ‘finished’ with the squash, it’s a good idea to let it sit in a nice cool place for a couple of months before harvesting the seeds. I’ll not go into this step much other than to say that you typically need to leave the produce on the plant longer than for eating, and often letting things dry is a good indicator.
Remove the seeds:
Seeds are often “packaged” by the plant in some kind of protective cover. Beans have pods, corn has a husk, onions have a little papery husk, radishes have a very woody pod. While you don’t HAVE to remove the seeds from these devices, it’s reduces the space a lot and sometimes eliminates the eggs of pests or spores of molds. For squash, the seeds will be happy to overwinter in the shell for many types, but will turn into a rotting mass when it thinks spring has arrived as the moulds ‘open the package’ to let the seeds out… You probably don’t want that in your refrigerator.
For some seeds, like beets, they are packaged in groups of “a few” in a single hard little dried package. What we call a ‘beet seed’ is actually a package of a few of them. It’s just too hard to separate them and the plant expects this environment anyway, so don’t be too surprised by that type of plant.
For corn cobs, simply letting them dry, then rubbing the kernels off with a strong thumb, works well. (Though sometimes I need to pry one or two loose with a fork to get it started ;-)
Cleaning the Seeds:
For naturally dry seeds, this may be nothing more than shaking them in a collander to let the dust and grit fall through, or blowing the bits of leaves and husks off in the palm of your hand.
Some fruits, like tomatoes, have the seeds in a “jelly”. Just cut the fruit in half and squeeze out the jelly. Traditionally you are supposed to dump it in a jar with about an equal amount of water and wait a week or so as it ferments. This removes the jelly and kills a bunch of potential pathogens on the seeds. Then they are washed in a sieve and dried. I’ve had no problems just separating the seeds from the jelly with a sieve, then spreading the ‘seed paste’ on a paper towel and letting it dry. I cut strips of dried seeds stuck to the paper towel as needed for planting. Yup, paper and seeds both. Think of it as home made “seed tape”. (Just not fond of random fermenting jars on top of the fridge… though I’ve done it and you get a neater cleaner seed.)
For squash a similar fermentation can be done. I’ve just washed them in the sieve and spread the seeds on a glass plate to dry. When dry, rubbing in your hands will result in a ‘dusty layer’ that you can blow away “winnow” and the cleaned seeds. You don’t always have to do things the way everyone else does them…
For seeds like Amaranth and some other “grains”, I’ve found that some sieves or colanders have just the right size for the seeds to pass through leaving the seed coats behind. For others, a trip to the hardware store to buy different sized ‘wire screens’ can provide nice separation. Though typically if it’s that much trouble, I just winnow off what I can and put the rest in a coin envelope. For others, placing the seeds in a broad bowl (sometimes with rubbing between the hands to loosen the husks) and blowing on them will send the husks flying and leave the seeds behind. Welcome to the world of threshing and winnowing. A gentle breeze or a cheap electric fan are your friends. No, you don’t NEED to winnow. I’ve kept seeds in their husks. It’s just more dusty and bulky. And a few more bugs are kept in the seeds.
If you get “into this” more than just casually for a few corn and bean seeds, there is a great book on the whole process of “Seed Saving”. It covers each plant in detail, with custom directions for things like how far to plant away from other varieties to keep the seeds pure, and exactly what quirks each seed type might have. (Such as the need for “biannuals” to overwinter before they make seeds the second year. Though I’ve been known to put beets in the refrigerator for 2 weeks in July and convince them August was a new spring ;-) The most common biannuals to find in the garden are things in the beet / chard family and those in the cabbages and kale family. Oh, and most onions.
It is also available from Amazon:
There is a list of seed exchanges and providers of heirloom seeds at this link: