I am trying to sprout some of my native ribes aureum seeds. I’ve read online that they need to be cold stratified for 2 months at freezing or below freezing temps. Does this mean just throw them in the freezer for two months or do I need to have them on a wet material that freezes like a damp paper towel or soil?
No you don’t want to freeze them wet probably not a good idea. I grew out the same species I planted them before winter. You can freeze them for two months or just plant them outside. I did the latter and they germinated well.
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I cold stratified a bunch of seeds this winter (3 months) in the fridge. I stratified Pacific Crabapple, Myrobalan (Cherry plum), and Quince seeds. Almost all successfully grew into seedlings when planted in the spring.
Stone fruit seeds with a hard outer shell like plum/cherry plum, apricot, peach I would carefully crack off the outer shell with a pair of vice grips. I would wrap the seed in a paper towel and adjust the size of the vice grips so as to not damage the fragile seed inside. Next I would soak the seeds to be stratified in a bowl of luke warm water. The time the seeds were soaked could vary from a few hours to overnight depending on the variety of fruit seed.
After soaking the seeds I stratified them in a damp mixture of 50% coco coir and 50% wood shavings stored in ziplock bags in the fridge. The temperature in the fridge was generally about 2-3 degrees celcius, but sometimes I’d put them in a part of the fridge that was just below freezing for a week out of each month. This seemed to work far better than the standard damp paper towel stratification method I’d used in the past.
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I’ve had the best results using damp peat moss at a ratio of 5 parts peat moss to 1 part water. Not sure where I got that ratio from any more but it gets the job done.
The problem most people have is rot or mold because they have too much moisture and a non sterile media. The 5:1 ratio basically humidifies the seeds so they’re not in constant contact with too much water and the peat moss, while technically not sterile, has very little nutrients to feed microorganisms and is on the acidic side which further inhibits growth of “stuff”.
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Thank you! I’d imagine there was some moisture in the ground where you threw the seeds? Think I should emulate? Sounds like it works for @collitchboy
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Thank you for the great write up! I’ll definitely be incorporating your method into my trials.
Thank you for the great information! Have you cold stratified things that require freezing using this method?
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Come to think of it, I wouldn’t mix in the coco coir with the wood shavings for stratifying small dark colored seeds. It makes picking out small dark seeds kind of difficult with the dark coir mixed in. The success rate on the moist wood shavings alone seemed about as good as the combination of the two mixed if I recall correctly.
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Don’t freeze them. They need 34-40F for stratification, not below freezing. It’s just like winter chilling. There’s none below freezing.
Also there’s no need to remove the hard shell. That’s protection. Nature knows best and nature doesn’t mess with all the extra stuff. For instance, I planted black walnuts last fall. You can’t remove the hard shell from those without mutilating the seed. They came up just like they have for millions of years in nature. Just because you can remove the shell doesn’t mean you should.
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Im growing some from seeds too, update us on how it goes and which method you use please!
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Has anyone used GA3 as an alternative for cold stratification?
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I’ve not frozen seeds as a method of cold stratification. I only put them in the fridge for some amount of time depending on species.
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@Rawnutphobic
Here is what “ seeds of Woody plants in the United States”
( a great resource book !)
Has to say about Ribes ….
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I stratified some english walnuts last winter in my garage. I put them in some moist woodchips and just let them sit for several months, where they probably got below freezing several times. I periodically checked up on them and took them out when I noticed them starting to split open. I had an 8/8 success rate with this method, and all sprouted and grew. Not all survived the transition outside, but that is a different problem.
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