Cold stratifying seeds

[tripsis]

What is the simplest method for cold stratifying seeds? I have several species which require cold stratification that I'd like to grow come spring. I was thinking of doing it in the fridge, but don't want to have to check them all regularly to make sure that they haven't started germinating, etc. So planting outdoors now seems like the easiest method, but what should the medium be? Is seed raising mix alright, or should it be inorganic, like coarse sand?

Thanks!

[applesnail]

ive tried S albidium with cold stratification with seeds outside as winter gets very cold here, but they got attacked by mould and the media was sprayed with fongarid and the ones i put in the fridge in a mix of sand vermiculite and crushed perlite havnt been attacked by mould, this new batch has been in the fridge for 2 months and i sprayed the media substrate of both with fongarid(inside and outside batches), before resting the seed half in half out so i could see progress in takeaway containers..

So from this i would suggest the fridge is the go, as i think the temperature flutuations had something to do with the mould attack outside as one day its cold the next the sun is out, so my theory is the fridge stays ambient and controlled cold!

Also i would sterilise seed raising mix in microwave if to be used, but i think inorganic media would be best, i used sand and nuked it also just incase but i dont think many pathogens really like sand!

Edited June 15, 2011 by applesnail

[planthelper]

i like both methodes fridge and nature, but for me, often nature won, specialy with tricky seeds like lago.

the trick is to place the seeds so you don't wear them out, by having them, to water them too often.

great, that reminds me to plant out my old lago seeds.

[tripsis]

I think I'll go with the outdoor method, as some of the seeds are extremely small (like fine sand). Not sure if it will be cold enough here though...

[planthelper]

if some of the seeds are very small, don't forget to sieve the top layer of your seed raising mix.

i'm sometimes to lazy to do it, but it definately is not a waste of time, and gives one the feeling to have done the best, one could do, with small seeds.

[Zaka]

Irie,

I'm just coldstrating some strawberry seeds...

4wks to 4mths in the freezer!~!!

I did do a bunch of henna seeds last year, successfully!!!

I'm hedging on 4wks though!!

Respect,

Z

[tripsis]

How are you doing it Zaka? With water, or dry?

[Zaka]

Irie,

Dry!

Respect,

Z

[tripsis]

Will it break to dormancy if dry? I wouldn't have thought so...

[Zaka]

Irie,

I think it should work that way??

If they were wet I think that the expansion, in to ice would fuck'em up!~

Respect,

Z

[tripsis]

But without water as a germination trigger, I would think that they would remain dormant. I could be wrong. Remember that where species are that have seeds that require cold stratification, the seeds would freeze over the winter, but wouldn't be dry.

This site advises refrigeration with moisture.

Refrigeration

Americans usually use the refrigerator to create an awakening winter for seeds. In fact, we've gotten so reliant on this method that we've forgotten that previously everyone simply planted seeds that need cold stratification outside once it got cold in the fall, usually in late October.

You need something to hold the moistness: traditionally, sterile soils like sphagnum moss, peat moss (good for acid-loving plants), clean sand (not from the beach or dredging--too salty), or vermiculite are moistened (not slopping wet), but you can also use a paper towel that has been wet and wrung out. Mix the seeds with the sterile soil--it's good not to use too much, because unless the seeds are large, you will be sowing the soil together with the seeds once they start germinating. Soak seeds overnight and mix in with the moistened sterile soil. Or if using a paper towel, fold the wrung-out paper towel in half and sprinkle the seeds on. Fold the paper towel closed and press it gently between your hands to get good contact between the seeds and the towel. With any of these methods, I normally use water that has some liquid kelp added to it, because kelp contains chemicals that help with germination of seeds. You can get liquid kelp at most garden stores in the summer.

Put the sterile soil/seeds or paper towel/seeds in a resealable plastic bag and put in the fridge. Three months is a good time, but sometimes you can get away with less, even 3 weeks. This is an area for experimenting. After a month, check the seeds every week or so to see if they are germinating. Some will germinate in the fridge; some won't. Plant them as you normally would when the time is up, whether they have germinated or not.

I have had much more luck using the paper towel method than using the ones that involve some kind of sterile soil. With a paper towel, it's a lot easier to open it up and see if the seeds are starting to germinate--or if they are just rotting. If they get brown spots around them or smell musty, they are rotting and should be tossed. (Seeds can rot because they were not stored properly before planting--usually too warm and/or moist. Keeping seeds at room temperature for too long causes many seeds to die, although some are actually conditioned this way to germinate better. Most seeds need cool and dry conditions for max storage life.)

Another way to use the fridge for brief cold stratification is to plant the seeds in individual jiffy pellets and put them in either a plastic covered container (such as for home baking little bread loaves) or in a store-bought "greenhouse" flat. Depends on how much room you have in your fridge. I have done this as well, for instance, with mandrake seeds before I started using cold water soaking.

Planting in jiffy pellets and then putting them in the fridge also works very well for seeds that need just a little boost of cold instead of a whole "winter." In that case, you only keep them in there for a few weeks. For instance, with poppy seeds that require cool temperatures to grow, planting them in jiffy pellets and putting them in the fridge for a week or so will cause them to germinate with great gusto once you take them out and put them in indirect light. I suspect refrigerating for just a few weeks would greatly help the germination of some annual seeds that usually are simply planted outside in the spring.

[Zaka]

Irie,

I'm not sure but it's my experience is that hard coated seed that would naturally over-winter, example Hemp, just need the cold, not ice!!??

BTW I would not plant the seeds then coldstrat......

Coldstrat then plant!! If ya get me??

Respect,

Z

Edited June 16, 2011 by Zaka

[gecko]

Sometimes just put seed into moist peat, coir peat or coarse sand in a small ziplock

into the crisper part of the fridge for 3weeks to 3mths.

some species respond better to moist peat or sand

warm for a few weeks to give seeds a chance to imbibe moisture before the cold strat.

If I'm impatient and in a hurry,

I use GA-3 in H2O at 500-750ppm in peat in a ziplock for a few days to a week

then sow into pots or flats.

depending on seed coat of larger seed,

sometimes I'll scald with water or scarify before stratification.

sometimes add smokewater to the peat, depending on species.

natural habitat of the seed in question often gives clues

ie. degrees of frost, yearly rainfall distribution,

geo-biological niches , fire occurence, dispersal vectors (animals gut acid; water- abrasion, leaching).

some fine seed needs light for germination and wont start if covered.

short answer to your question though,

peat or sand in ziplock bags in the fridge

Edited June 24, 2011 by gecko

[tripsis]

Excellent post gecko, thanks for taking the time to write it. Do the seeds germinate in the fridge, or do you just give them a specified amount of time, then sow afterwards?