Their age isn't the issue. Those are not "old" seeds (depending on the type). The storage is the issue. What is an "extreme winter" where you are located? A Georgia winter is very different from a Minnesota winter. :)

Basically, if they froze and thawed, froze and thawed then no. If they froze and stayed frozen then yes.

Dave

Also the humidity and moisture they are exposed to matters. If the seeds were resealed back up, that helps. Dry seeds keep much better. Also some seeds keep longer than others. Sweet corn likely keeps ok for a couple years.

I'm actually testing old seed to see if it will still germinate. Leaving it on a plate on the counter in a coffee filter with a paper towel over it and using a spray bottle to keep it moist.

It can also depend a bit on what seed it is- some seed is good with the cold, and that's why it's popular for wintersowing. Other seed does not do as well.

So maybe tell us what seeds they are, how they were stored, and what the weather conditions have been? That would be helpful.

Cold does not kill dry seeds; warmth does. I keep dry seeds in the freezer in sealed containers. They still germinate after 20-30 years. The colder, the better. But if they are out in the open, and if moisture has condensed on them, germination may not be good. You should test a few, like prairiemoon did.

I live in New Jersey, so we've had plenty of freeze and defrost weather the past years. They were in the original seed packets, open but the tops were folded over. Some corn, tomatoes, snap peas, I think there were some herbs in there too. I have about 15 of the burpee on-deck corn kernels that I don't want to waste. If I sprout them on a paper towel/ coffee filter to test viability, will they survive being put into potting mix at that point, or is it better to test directly in the pots?

I personally think the freeze-defrost is not an issue... in nature the seeds can freeze and defrost all winter long and they still sprout in the Spring. But I am no expert on seed germination and would have to yield to the experts.

As noted, the cold isn't an issue. The question would be how many hot summers those seeds endured in that outdoor shed. Of course, if they were just sitting in that outdoor shed in opened paper seed packets, exposed to the humidity, and depending on exactly what kind of seeds, they're probably worthless after a year or two. The lesson is that it is worth the time and supplies (doesn't take much) to store seeds properly.

Is a plastic bag or container in the freezer the correct way to store seeds?

You can plant the sprouted seeds directly, in fact a lot of people pre sprout their seeds prior to planting to guarantee the seeds germinated and only one viable seed is used per pot. It cuts out on waste of thinning seeds down the road. I did this with my old pepper seeds. they just hit 3 years old and the germination rate was only about 70% so it helped me get the most out of them.

Well sealed plastic (e.g. ziploc) bags. Ideally with a packet of silica gel inside. It's that simple. Do not ... DO NOT ... open the plastic bag while the contents are still cold. If you do, you'll condense water on the seeds. Let it warm up thoroughly before opening. I'm also a little concerned with temperature cycles, especially freeze-thaw. So minimize those by using separate ziploc backs for different seeds. That is, if you want to get some tomato seeds, don't warm up everything along with them in order to get them.

Freezing seeds requires that they be carefully dessicated, and that can take some trouble. That's why I mainly use the fridge, not the freezer. Purchased seeds are already well dessicated, though.

I'm sure there are great GW threads on this.

I also recommend refrigerator storage rather than freezer storage because it is so much easier to do unless you have experience at correctly drying seeds and handling frozen seeds.

As I said above, seeds that freeze and then thaw, freeze and then thaw again are automatically exposed to humidity in the process and that cycle quickly kills them. I would expect a New Jersey winter to have been quite hard on them.

But what we are talking about is a totally different process than what happens in nature in the ground so it is indeed an issue contrary to the post above. Not only do frozen seeds have to be handled very carefully when exposed to the air as Dan said but the survival rate for germination in nature's conditions is marginal at best so not comparable.

Of the seeds you listed you should be able to tell by looking closely at the corn and pea seeds if they have germinated and died. They will be cracked and have a fine hair attached. If they look intact then they may be worth trying. Some of the tomato seeds might germinate but at a much lower rate than normal and I probably wouldn't waste my time with them unless they are a rare variety. Most herbs seeds other than members of the allium family are quite tolerant of abuse so worth planting.

You can learn a great deal about proper seed storage over on the Seed Saving forum here. It has a great set of FAQs on the topic.

Dave

PS: be sure to add your zone/location info to your profile page so it comes up on your posts.

' in nature the seeds can freeze and defrost all winter long and they still sprout in the Spring'. That may be the case regarding plants which hail from habitats which have freezing Winters. We still don't know which seeds the OP has. If, for example, they are plants from tropical/sub tropical climates like tomatoes or eggplant, I would suggest they will not be equipped by nature to deal with being frozen and may well suffer.

Thank you all so much for your help! I look forward to a fruitful summer with guidance from all of you experienced gardeners.

That may be simplistic to say that seeds in nature can easily survive repeated freezing and thawing. They may not survive it very well, and the fact that some sprout should not be taken as assurance that most of them did, in fact, survive. One strategy for a plant could be to make a few seeds that withstand repeated freezes very well, but another would be to make LOTS of seeds that don't necessarily. I suspect the latter is more common.

That's true that real tropical seeds won't freeze will, but I know tomatoes and eggplants do just fine, if properly dried.

I would try out the peas first, as they will sprout quickly indoors and can then be planted out. I usually soak them overnight, and they should plump up, then I drain and rinse them every 8-12 hours until they sprout a "tail". It usually just takes a couple days. Then I carefully plant them.

Of course, even if they do sprout, it's no guarantee the others will, but it might be an easy indicator.

That's pretty extraordinary. I have to assume that the dry air in AZ helped a lot.

Ditto on DID's comment... that is remarkable germination for seeds exposed to (presumably) prolonged heat.

A couple of notes regarding plastic bags for seed storage. I have had great seed longevity using plastic bags, but have two words of caution. All plastic bags are not created equal; I recommend using zippered freezer bags, since they are heavier duty (to resist punctures) and have better seals... both aspects reduce the chances of moisture intrusion. Along with the recommendations already given regarding proper handling of frozen/refrigerated seed, special care should also be taken to avoid sunlight. Even a short exposure could cause rapid heat buildup within the bag, and could very quickly kill the seed within. When planting, I either transfer small amounts of seed to other containers, or keep the bags in a cooler (without ice) and remove the bag only long enough to pour out seed.

I don't like ziploc bags. I use ball mason jars and peanut butter jars for seed storage. I think they make a much better seal.

If you freeze your seeds, and you want to take some out, just place the sealed container in a room temperature location for 45 minutes or so, to let the seeds warm up. Then you can open it and take the seeds out. If you take the seeds out cold, then everything in the container is going to get condensation on it.

I don't use any kind of dessicant when freezing seeds. So far I have gotten good results without it.

A sensible (cheap, compact) strategy, which I have yet to do, actually, is just to use nested ziploc bags. Say, one bag inside another. That would guarantee against moisture intrusion, Yes, bottles make good seals, but I find that they take up a lot of valuable space that isn't flat, as are seed envelopes. Ziploc bags are really economical of space.

The space issue is one of the main reasons I chose to use plastic bags. I roll the bags up, squeezing out any excess air, then stack them tightly in boxes to keep them from self-inflating. Low oxygen is one of the factors for extending seed life, so the less air enclosed with the seeds, the better. Besides, I'm storing 300+ different seeds, in widely different quantities - and sometimes in multiple lots - so jars would be impractical.

But jars are probably still best container for extended frozen storage. When I have a freezer dedicated to seed storage (which will hopefully be this year) I will use multiple small bags within each jar, so that I can quickly & safely remove a small quantity without thawing the whole jar. The bag-within-a bag method might work too, only time & testing will tell.

For seed storage, I think the manual-defrost chest freezers are best, since they don't keep cycling the temperature around the freezer walls. Chest freezers are also very energy-efficient. The cold air doesn't pour out when you open them. But chest freezers don't give you nearly as good access as uprights.

I like to put a few plastic gallon jugs of water in the freezer and let it freeze. If the power goes out, the ice keeps the freezer cold for a long time, especially if you cover the freezer with a big blanket or some big sheets of bubble wrap.

What jars do is to protect seeds from pressure, as in, when the ziploc bags get rolled up, squeezed, and tossed around. But that's a good point about bags minimizing air content. There is some evidence that seed lifetime decreases with oxygen concentration. I guess you can purge the bags with nitrogen or CO2. But interestingly, vacuum sealing has been found to be the best for seed storage, and even more effective than refrigeration. I guess if you want to really do it right, use a Foodsaver on your seeds, and stick the bags in the freezer in a bottle. Though I think the smallest Foodsaver bags are pint-sized. That's pretty big. BTW, there are rumors around that seeds need oxygen to survive. That's simply wrong.