The best way to determine if a seed will benefit from a moist chill is to look up each seed you want to plant using one of the available seed databases.

If stratifying is going to be helpful, it won't matter if seed you have collected yourself or if seed you have purchased. Regarding your lettuce, lettuce seed can become dormant if stored at temps higher than approx 75 for an extended period of time, in which case a moist chill can help to break the dormancy - so the difference may be in your storage.

There are just a very few places seed can be purchased stratified and in those cases you will know. Whether that particular seed needs a moist chill, or a warm moist period preceding the moist chill, the key is moist - and once moist it must remain consistently moist, if allowed to dry again the seed won't be viable.

Any seeds you purchase that have had the stratification begun before purchasing would then arrive moist packed and not in a paper envelope. Gardens North and a few specialty seed companies will sell seeds pre-treated but it isn't practical for most major seed companies.

Here is a link that might be useful: Clothiers

Have you read the Stratification FAQ here? Linked it below.

Honestly, there are very few of the commonly grown seeds that require stratification. None of them are common vegetable seeds.

It is a process required by several uncommon, unusual flower seeds that are seldom grown by the average home gardener and perhaps a few very uncommon vegetable leafy greens .

So as morz said, simply looking up the specific seed is the best approach.

Can some of them that don't require it still benefit from it? Perhaps, but it unnecessarily complicates the process in most cases. The extra time and effort involved in stratifying them far outweighs any benefits gained in the majority of cases.

So if you wish to do it, fine. It won't hurt assuming it is done properly. But I sure wouldn't encourage anyone to do it unnecessarily. As an alternative you can simply store all your seeds in the fridge as many do and eliminate the issue for 95% of all seeds.

Dave

Here is a link that might be useful: Stratification FAQ

The lettuce I start indoors under lights at 65 degrees germinates faster than the ones I plant outdoors in the cold.

They say lettuce needs cold to germinate but I see that it doesn't matter.

Like Dave says, just a few flowers need it. For them, I pot them up and put them in the fridge for a few weeks first.

Many of the seed from your own plants, will germinate if planted soon after harvesting, even though the same seed if purchased will require stratification. The difference is the amount of time the seed is kept in the dry state, which allows the seed to develop germination resistance. Al

Once again, you guys have taught me so much.

Yes, I have Tom Clothier's book printed out as a desk reference...and in fact is probably what go me started on stratification in the first place. :) I have several seed starting books besides his, and compare entries.

I used lettuce as an example but my challenge has been flower seeds. Anemone, Delphinium, Alcea, Lady's Mantle, Bergenia, Columbine, Lupine, Campanula, Cranesbill, Dianthus, Echinacea, Gaillardias, Heucheras, Lewisia, Lobelia Cardinalis, Monarda [yes, monarda!], Penstemon, Prunella, Rodgersia just to name a few.

I did not realize that seed storage temps and length of time kept dry were big factors to consider. I do keep my seeds in a frig, off season, and I try to use fresh unproven ones.

I had great luck with Alstomeria seeds this year, and have about 18 healthy seedlings. Here is my basic procedure: if the seed is big enough to handle, I papertowel treat it in the frig. If the seed is tiny, I plant them in cells and refrigerate the flat, but some seeds need alternating "mother nature" fluctuations, in which case I plant in cells and leave the flat outside. Namely Penstemon, Delphinium, Heucheras. I think I'm following the guidelines fairly well, but still have very low germination rates.

Still, you answered a big question that I had about seed companies. They do not normally get involved in this process, so is that to say the fresh seed can be planted directly upon receipt and only require stratification if you wait awhile. Hmmm, I must ponder this.

Carnations: guides say stratify, seed packages don't. I've had bad luck both ways.

Most wildflowers do better direct sown, but unless you plant en'mass, how do you really know the success rate....many times I've never had a one a pop up.

Nasturtium...to chill, or not to chill? Hollyhock...yes or no? Hollyhock reseeds like weeds when left alone, but just try to plant a specialty one...not so easy.

I would enjoy reading specific success stories on particular seeds if you wish to tell of them.

runswithscissors - it sounds as if winter sowing would be helpful to you. You wouldn't need to worry about stratification at all. You let the winter weather take all the guess work out of it. All the plants in your second paragraph are hardy and could be winter sown.

Here is a link that might be useful: Winter Sowing forum

wow thanks flora, i didn't realize that forum was there.