How long to keep in cold stratification?

claysoil(z6 PA)February 23, 2004

I know that the seeds need 6 weeks of cold to start sprouting. My question is at what point do you figure that any unsprouted seeds need another round of warmth? I have some of the Elisabeth Town hellebore seeds in the fridge and am wondering at what point this summer I should bring them back to warmth if they have not sprouted.

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Greenmanplants(UDSA Zone 8)

Planted fresh, you should get 80+% germination in the first spring, (actually here it's usually December). I pot these up at the first true leaf stage and usually scatter the rest of the seed compost resulting in most of the other 20% appearing in the second year.

If you don't have a very high germination in the first year, it may be worth going through a warm/cold cycle again, you can either do this naturally by leaving any seedlings in the pot for a year(OK if only a few and you have a deep pot) and leaving them outside. Or you could try delicately pricking out those seedlings you have at cotyledon stage(take care not to damage the stems as they will quickly damp off), and artificially warm and fridge the seed tray during the next 3 months. This is when it pays to have used a very open gritty compost as the seedlings will prick out more easily. Once they have the first proper leaf, the root will be about 4" long and you will need to lift all the compost out to break them out, if your careful, you can return the rest of the compost and dormant seeds to the pot.

Cheers Greenmanplants

    Bookmark   February 24, 2004 at 4:24AM
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Fleur(z5)

Mine germinated in the fridge last year.

    Bookmark   February 26, 2004 at 2:38PM
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morz8(Washington Coast Z8b)

I just now looked back at my notes from last year, and I planted my Tasmanian seeds in pots outdoors (where temps were averaging about 40F) on January 18, 2003....it was almost 10 weeks before I had any germination, with the first seedling appearing the last Tuesday in March. I hadn't remembered it taking that long, but those are definitely the dates....

    Bookmark   February 29, 2004 at 8:29PM
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claysoil(z6 PA)

But then, MorZ8, your seeds were no longer at temps below 40 degrees, right? I can't imagine it being that cold in zone 8 at the end of March. How much time did they have at temperatures of 40 or lower?

    Bookmark   March 1, 2004 at 4:08PM
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morz8(Washington Coast Z8b)

Sorry Claysoil, I didn't keep daily records.

A good deal of the 10 weeks would have been at averages of roughly 40F, our March can be quite cool (like our summers). For example, today it's 50 at almost 2PM, but with the clearing skys, the overnight temp is predicted to drop to low 30s, same for tomorrow and tomorrow night. Yesterdays high was 45, and we are forecast to have rain and 40ish temperatures through the beginning of next week starting on Wednesday.

So the seeds would have had some days that were out of the 40F range, but not many in a row, and few nights if any that left the '4' behind. Coastal Washington Zone 8 is much different than Texas ....

    Bookmark   March 1, 2004 at 5:03PM
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Terry_NY(6)

Last year was my first time growing and I did it all wrong but still had germination. In fact some, not many are still germinating. Lesson to all, keep your pots and water them, you may be lucky and get more germination. This year I did not get my seed till February and I have them in a unheated area of basement. Hope it is cool enough!

    Bookmark   March 4, 2004 at 10:27PM
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claysoil(z6 PA)

Coastal zone 8 is a lot different than I had thought! thanks for explaining Mor. I'm wondering if I need to put my outdoor pots into an ice chest since we've had 60 degree days this week! Glad that I put over half of the seeds into the fridge without potting them up.

    Bookmark   March 6, 2004 at 1:39PM
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