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Germinating tomato seeds

Here's something that I've been wondering and concerning myself with this fall.

I've collected about 10 different varieties of heirloom tomato seeds, as well as around 10 varieties of peppers. I want to grow them all this spring, both to enjoy the fruits and the harvest lots of seeds this fall.

My question: Is there anything special that I must do to ensure the germination of these seeds? Some of the ones I have were fermented by myself (the actual heirloom tomato was given to me by an uncle), but the ones I received from trades I can only hope were also fermented properly.

Aside from this fermentation step, is there something more to do to these seeds before they will germinate? Should I stratify them in the fridge/freezer first?

Ogunquit, ME(Zone 5a)

To keep tomato seeds viable I store mine in paper envelopes and place them in a canning jar that has a good rubber seal. I also add a packet of silica gel which acts as a desiccant to absorb any moisture and I pack them away on the basement floor where it stays quite cool constantly and is dark. Those seed I do not plan sowing next season I treat the same way but place them in the freezer. It's very important that seeds that are placed in the freezer for storage are dry (less than 8% moisture). A way to test this is a seed that is dry enough will break when bent as opposed to bending. Freezing when dry does not hurt the seed and they will maintain their viability ten times longer.
Tomato seeds don't need to be stratisfied, they need to be kept in a cool, dry area. They will remain viable for 4-10 years depending on the variety.
Regarding seeds obtained through trades, I sometimes ask what, if any, process was used in saving the seeds. I did have a person send my some Pineapple tomato seeds a short time ago which still had some tomato pulp/gel on them. He told me he soaks his seeds in a mixture of 6 drops of Clorox and a pint of water for a few minutes before he sows them and has done so for many years with great results so I thought I might give it a try this spring on the ones he sent me. It's always fun to experiment!

Thanks for the info. So far, I have them stored in paper envelopes in a non-airtight tupperware container in a room of about 70 degrees.

I'll move them into a cooler area right away and put them in jars. Hopefully it's not too late for these seeds.

Ogunquit, ME(Zone 5a)

Your welcome, Dave, the seeds will most likely be all right since you mentioned you will be planting them next year and you probably haven't had them stored all that long. One of the biggest factors is fluctuating temperatures and humidity levels. High levels of either have a detrimental effect on seed viability. Humidity is the worst which allows microorganisms to grow. That's why if you store them in a canning jar with a rubber seal, in a cool basement or your refrigerator or freezer with a desiccant they will last quite a while. For a "free" desiccant, save the litle packets that come in shoe boxes with new shoes or purses or you can get silica gel at craft stores.

Happy gardening!

Lyndeborough, NH

Storge I kept some Brandywine and Amish paste seeds in the original seed envelops at room temps for 6 years.

For seed start (after 12+ years of doing it) I like the Jerry Baker method, weak tea in fringe overnight.

Then tomatoes and peppers onto a heat mat ~~RE Stokes and Johnnys seeds~ Ideal germinating temp is 86F. Tomatoes and most peppers up in 3 to 5 days.


Kansas City , MO(Zone 6a)

If I might ask a question... I also have obtained several packets of heirloom tomatoes, and was thinking about where to plant what in the spring (I know I'm a little early for this, but I'm trying to block out all the snow that's blowing around my windows with happy warm thoughts!), and was wondering about pollination. If I plant different types of tomatoes close to each other, will the seed stay "true", or do I need to plant all far away from each other like corn? Thanks in advance! Kathy

Ogunquit, ME(Zone 5a)

Tomatoes are self-pollinated; they usually pollinate their own flowers so you can grow varieties side by side and still get about 100% pure seed or for better odds you can separate the varieties by 6'-15' for 100% purity. Those most likely to cross pollinate if planted closely because of their protruding styles are the currant tomatoes (L. pimpinellifolium), tomatoes formed from double blossoms on beefsteak varieties (L. lycopersicon), and potato-leafed varieties of L. lycopersicon.
Hope this the snow continues to fall here's a great time to grab all those gardening books and seed catalogs and dream of warmer days :)

Source: Seed to Seed, published by the Seed Saver's Exchange

Lyndeborough, NH

A simple method of preventing cross pollination

At about the time the flower starts to open. Make a small "bag" with panty hose. Cover the blossom(s)
snug enough to keep small insects out.

When the blossom fully opens, tap the branch lightly every day for a few days in a row (or vibrate with electric toothbrush or similar item)

Watch these buds closely, as soon as you can see the tomato start to form remove the panty hose and mark the blossom(s)

For seed saving, You should allow the fruit to go just beyond fully vine ripe. This allows more seeds to become fully mature.

If you are going to trade also watch very closely for plant diseases. Many plant diseases can be transmitted thru the seeds.


Thanks for the good info. I'm worrying a lot less about my tomato seeds now.

My wife ordered the "Seeds to Seeds" book for me for Christmas. I can't wait to dive in and learn all that the book has to teach.


Lyndeborough, NH

I like one on "Seed Ssaving" by Rob Johnston Jr. Owner Johnnys Seeds. Price is a whopping $2.95

Richmond, KY(Zone 6b)

A couple of comments on this thread.

Both tomatoes and peppers are in-bred, self pollinators. However, while tomatoes will mostly stay pure if planted near each other, peppers willl not. In fact, they will cross-pollinate if you look at them crosseyed. So if you are growing more than one variety you have to isolate them---either by distance or by caging.

This is a very real and present danger. Jeff Nekola, a botonist with UW at Greenbay, is an avid pepper grower (up to 150 varieties/year). He's found that with traded seeds he averages 1 in 5 plants that do not breed true to type; and has run as much as 1:3.

On saving tomato seeds: There is a growing (and unfortunate) trend away from fermenting seeds. There are a couple of problems with this. First, the gel contains anti-germination compounds that nature put there to prevent the tomatoes from sprouting in the fruit. Fermentation removes them better than any other method. Second: Fermentation kills many pathogens. So you produce healthier seed (and next year's plants). Another way to do this is by freezing. Freezing, incidentally, is a way to increase how long seeds stay viable. With normal storage (cool, dry), tomato seeds remain viable for 4-10 years, depending on variety. Freezing seeds keeps them viable for up to 40 years.

One other comment on freezing. If you do keep seeds in a freezer, make sure that they come back up to room temperature before opening the container. Otherwise condensation will form on the seeds, which could viability unless you plant them right away.

Good stuff, Brook. I ferment all my tomato seeds, and always ask a trader if they did the same with the seeds they are trading to me.

I didn't realize that peppers will cross pollinate so violently. I have (I think) 6 varieties of peppers that I will be planting this year. I better keep them on all corners of the garden.


I am concerned about passing on all this definite information about seed storage, viability and germination. Perhaps some of it's just fashion? I remember when it was considered the right thing to lay your baby face downwards to sleep, and now laying a baby face down is the worst thing you can do.

I've read that seeds should be stored in a fridge and not at room temperature and not in the freezer. Norman Deno said in his book that maybe seeds should be stored moist and not dried. Other people have read that they need to be stored dry, and/or in the freezer. I keep reading posts about sowing seeds outside in the autumn to germinate in spring, as if this is new, but it's common practice over this side of the Atlantic.

Sometimes I just look at my seeds, and decide how and when to sow them by what feels right. Don't you think maybe we're trying to apply rules that nature hasn't written?

Sorry, this isn't really about tomatoes, just a general observation.

Richmond, KY(Zone 6b)

And some very good points, Mary.

The "rules" are never hardfast, because any gardener can point to exceptions. So what we are doing, really, is following established botanical procedures.

Let's keep in mind, however, that those procedures are designed to produce the best-case scenerio. So, if we follow them, we are likely to be better gardeners in erms of germination, seed viability, etc.

A case in point. The established standard is that onion seed only remains viable for two years. Yet I have friends who grow onions from seed that is ten and twelve years old.

"Viability" touches on another point. Most of these "rules" are established with market growing in mind. A viability figure (i.e., three years) means that at least 50% of the seed will germinate when it is three years old.

As for storing seeds moist, I don't buy it. Moisture is what signals seeds to come out of their dormancy. If we do that too early, the plant will not grow, because other necessary conditions (temperature, day-length, etc.) are not right for them.

Conditions for seed storage have to do with the length of time you intend keeping them. If you keep seeds at room temperature (but dry), you are unlikely to have any viability problems the following season. Or even the season after that. But what about ten years from now?

The fact is, every seed bank in the world stores seeds by freezing them. This extends viability to about 40 years at regular freezing temperatures (i.e., zero degrees F). In liquid nitrogen, they keep virtually forever.

Does fashion enter into it? To a certain degree, yes, as writers such as myself are always looking for something new to say. But more than fashion, what enters into it is personal choice---how is it you want to manage your seeds and your garden.

The potential problem arises, however, when you get into seed trading. For that, you want to assure the highest germination levels, the purest seed, and the strongest levels of genetic vigor you can. It's only fair to your trading partners that you do this. And to achieve those things, you stick as closely as possible to the established procedures.

In other words, you follow the rules as much as possible

I'm not a new gardener, I've been gardening on and off for over 50 years. I've swapped seed with people all over Europe before going on the internet, and I'm a member of several societies that have seed distributions. I think nearly everyone I've had seeds from stores their seed as I do, in their fridge. I don't grow annuals, and I think most people over here who do grow them buy their seeds every year, or more usually buy the plants. I grow (and swap seeds of) mainly alpines and perennials, and I don't expect very high germination because the seeds I grow are generally accepted as difficult, and often take several years to germinate.

Perhaps because we don't have extremes of temperatures, the range of plants we can grow here in Europe is much larger than those you are used to growing in the US, and serious gardeners usually grow perennials rather than annuals. We also have much less gardening space than you do, so only have room for one or two of anything.

I wouldn't feel happy keeping seeds moist as suggested by Professor Norman Deno of Pennsylvania University, but I also wouldn't like to use a dessicant. Surely a seed with a large store of food for the embryo (like a seed of a bulb, for instance) would need to have that store undamaged, and small seeds would be dried to death. Dehydrated seeds cannot always be rehydrated succesfully.

My son has a Masters degree and tell me if you fast freeze a seed by dropping it in liquid nitrogen, you get little grain growth, leading to lots of small grains, and hence small ice crystals. If you slow freeze, you get a lot of grain growth, and therefore larger grains, and hence large ice crystals, which could damage or kill cells. (In understandable terms, if your ice cream defrosts and then refreezes, it goes grainy with large crystals and won't smooth.)

The reason freezing works for seed banks is that they have special freezers, not domestic ones. They don't keep human embryos in domestic freezers, either.

I still think natural instinct (green fingers?) is as good a method as any to use for assessing the methods to use for sowing seed. It works for me, combined with interest, knowledge and experience.

Cockeysville, MD(Zone 6a)

I grow out a number of heirloom tomatoes every year and I keep about 8' between plants so there is no cross pollination. I started out with 6' two years ago and Chuck Wyatt of convinced me to go to 8' last year. I've always been intrigued by the Radiator Charlie Mortgage Lifter stories and am considering planting 4 different varities in a small group for a couple of years to see what happens...This past year I did plant two or more of the same variety together in a "cluster" so they could happily cross-polinate. I'd rather be safe than sorry.

Mobile, AL(Zone 8b)

I'm new to tomato seed keeping. Could someone please tell me what the fermentation method is, and how it is accomplished?

Richmond, KY(Zone 6b)

Sure thing, Jan.

You put the seed mass in a suitable container---I use clear-plastic disposable drinking glasses myself. But any waterproof container will work.

Add an equal volume of water to the seed mass.

Put the container in a warm place, but not in direct sunlight. It's nice if you can do this outside the house, because fruitflies and other critters will be attracted to it, and some people think it smells badly.

One a day, stir the contents.

The fermentation process will begin in about three days, and takes as long as a week to complete. The viable seeds sink to the bottom. Non-viable seeds, other trash, and mold will float on top.

When you think all the seed that will sink has, pour off the crud, and rinse the good seed two or three times. They lay it out to dry, preferably on screens. I use special seed drying racks I designed and build myself.

Complete drying will take about three weeks, depending on humidity.

For a fully description, see the tomato installment in my Heritage Garden column in Le Bep's Garden Magazine (

Hope this helps.

Mobile, AL(Zone 8b)


Yes this information helps alot. Thanks for answering my question. I love this forum.

New Paris, OH

If you are keeping seed be sure to have enough plants of the same variety to ensure a good genetic base. I have read a minimum of 8 plants and than take seed from only the healthiest 2 or 3 plants. it is best to plant them in blocks rather than lines though i have not had any problrems with linear planting.

Cockeysville, MD(Zone 6a)

I use recycled plastic or old glass containers...whatever I have around. Hospital cups are a good size for me. I follow the "gross" method...when it is REALLY gross like 3 days or so....I rinse repeatedly until the "crud" (good word Barb!) settles. I use paper plates for drying and just write the name in permanent marker. I generally do more than one variety at a time so I am neurotic about proper labeling. I learned not to use water soluble markers the hard way...... The plates sit on my mantle (and any usable surface)in layers until dried. Viola! Not rocket science but well worth protecting your seeds from diseases!

Richmond, KY(Zone 6b)

Do you have any problems with the seed sticking to the paper plates?

Cockeysville, MD(Zone 6a)

"Plate sticking" is not a big problem for me. I use the plates that are not supposed to absorb grease...I think they just add a bit of wax to the paper. A few stick but I pry them off. I think making sure the seeds are well rinsed helps too. If I have a really wet mix I sometimes roll the extra bit of water off the edge or use a paper towel to blot it up. A "trial and error" method that works well for me. Anyone have other methods to share?

I used styrofoam plates purchased at Wal-Mart. The surface is very slick and the seeds never stuck.

The biggest problem was the seeds sticking to each other.


Richmond, KY(Zone 6b)

That's always a problem, Dave.

The only solution I've found is to go through the tedium of actually separating them while still wet, by shifting them around with toothpicks, tweezers, or the like.

I do this. But I don't think most people bother.

That's almost exactly what I did. several times a day during drying I would pick up the plate and "swish it around", if you know what I mean.

I'd also poke around with a cotton swap (using one end cut off) to sort of seperate them. It worked fairly well for me - I only had a very few stuck together at the end of the process and those I seperate manually.


Mobile, AL(Zone 8b)

Seperating tomato seeds I think is a must. I planted several seeds this year that were stuck together. The resulting seedlings were way smaller than the others. Do ya'll think I should cull these smaller seedlings or seperate them and see if they catch up with the other?

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