Cold stratifying Japanese Maple seeds?

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How long should I cold stratify my Japanese Maple seeds? I have read everything from two weeks to 120 days. The instructions that came with the seeds said two weeks, but I am not that confident in the seller's horticultural knowledge.
 

Gnome

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I collected some in the fall of 2005 and held them in my unheated garage all winter until it seemed warm enough to plant them. This simulated a whole, if mild, winter outside. I got a pretty good germination rate. Last fall I collected some more and did the same initially. With the exceptionally mild winter we have had here I recently moved them to the refrigerator. If you start the process now and check them regularly you can remove any when and if they germinate.

I know that this does not answer your question directly but in my location our winters are longer and I don't face the same circumstances that you do.

Norm

EDIT: Hey I just had another thought. What you are really asking is what is the minimum stratification period, right? What if you simply went with the longer period and planted then. With the climate that you have, you would still have a fairly long season to get the seedlings off to a good start.
 
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Vance Wood

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I collected some in the fall of 2005 and held them in my unheated garage all winter until it seemed warm enough to plant them. This simulated a whole, if mild, winter outside. I got a pretty good germination rate. Last fall I collected some more and did the same initially. With the exceptionally mild winter we have had here I recently moved them to the refrigerator. If you start the process now and check them regularly you can remove any when and if they germinate.

I know that this does not answer your question directly but in my location our winters are longer and I don't face the same circumstances that you do.

Norm

EDIT: Hey I just had another thought. What you are really asking is what is the minimum stratification period, right? What if you simply went with the longer period and planted then. With the climate that you have, you would still have a fairly long season to get the seedlings off to a good start.
I agree with this approach. It works for me. If you use the refrigerator keep them in there till it is time to plant but check occassionally for early germination. Those tree will have to be removed and planted in a frost free environment. The rest you can plant in the spring.

I have found that J. Maple seeds do not mature till fall and after the first hard freeze. If you are hoping to stratify seeds so that you can get them to grow now I suppose that would be possible but what do you do with the new seedlings you now have growing for the rest of the winter? Maples do not do well indoors without some pretty sophisticated misting systems and lighting, aka a green house cultivation system. So you are better off using the natural cycle of things. You will wind up with healthier and more vigorous seedlings and not so much of a hassle in developing them.
 
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Gnome

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Vance,

I have found that J. Maple seeds do not mature till fall and after the first hard freeze.
By this are you saying that the seeds should remain on the tree until they have experienced a frost or that they need a frost throughout the winter to germinate properly. I collected mine this year in late Sept. or early Oct. and I know we did not have a frost that early.

Norm
 

Vance Wood

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Vance,

By this are you saying that the seeds should remain on the tree until they have experienced a frost or that they need a frost throughout the winter to germinate properly. I collected mine this year in late Sept. or early Oct. and I know we did not have a frost that early.

Norm
That's what I said, now whether or not that is entirely true is in the end results, the germination rate.
 

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These seeds were already removed and dried. According to many sites, I am supposed to soak them in water for 24-48 hours, then cold stratify them in the refrigerator for 14-120 days. It is the range of days that is throwing me off. My current plan is to cold stratify them for about 2 months (60 days) and plant them in late March, which in Southern California is already starting to get warm.
 

Brent

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If they are already dried, don't get your hopes up. JM seed needs to be treated while fresh from the tree. If it is overly dried it will be difficult to impossible to germinate. 90 days of cold moist pretreatment is what it needs. JM is somewhat unusual in that it doesn't need a warm period following the moist/cold pretreatment if the seed is fresh. It will begin to germinate in the fridge sometime between 60 and 90 days. When it begins to germinate, you can take it out and sow it all, or remove it as it germinates.

If none has begun to germinate after 90 days in the fridge, you are in trouble. Take it out and give it a warm/moist pretreatment. This is keeping it at 70F (easiest to do in a ziplock bag) for another 90 days. It may begin to germinate, but probably not. At the end of 90 days, if it hasn't begun to germinate, put it back in the fridge for another 90 days of cold/moist. If no germination at the end of this period, it probably isn't viable. You can open a few seeds with your concave cutters to examine the kernel. It should be creamy white and solid. If it is brown, soft, watery, or missing entirely (it happens), then the seed is not viable. I keep opening seeds until I find a good one. If I get to twenty without a viable seed, I throw the lot out.

I once germinated hybrid Acer palmatum seed over a two year period of alternating treatments described above to get them all to germinate. I never want to do that again. Don't buy seed, unless you know that it has been picked fresh from the tree and immediately sealed without any artificial drying. It has taken me hundreds of dollars in seed to learn this lesson.

Brent
EvergreenGardenworks.com
see our blog at http://BonsaiNurseryman.typepad.com
 

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If they are already dried, don't get your hopes up. JM seed needs to be treated while fresh from the tree. If it is overly dried it will be difficult to impossible to germinate. 90 days of cold moist pretreatment is what it needs.

Thanks Brent. Into the fridge they went. When I said they were "dried", I meant they are dry seeds off the tree from this Fall. I don't think they went through any special process aside from being picked up off the ground and placed in bags. However they didn't get picked up off the ground and immediately placed in damp growth media, if that's what you mean.
 

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Well, it's been almost exactly 90 days since I put my seeds into the fridge, and some of them are starting to sprout. I am removing and planting the ones that are sprouting, but should I continue to keep the remainder of the seeds in the fridge, or should I take them ALL out and plant them?

I am concerned because I started these seeds late, and if they don't start to develop shortly I am worried about how they will do this coming (mild) winter.

The photo shows the seeds in the vermiculite I was using in the fridge. They are currently in water (to remove the bad seeds) but I store them damp with a misting of anti-fungal spray.

 

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when should this be done?
If it is 90-120 days, should I do this that period of time before the first day of spring?
 

barrosinc

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So I just scheduled my agenda to stratify the seeds 100 days before the middle of spring just in case the temperature gets too low.

I hope this is right I couldn't find an exact source.
 

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I don't know that there IS an "exact" source - because it may depend on the tree, the seeds, when they were collected, etc. Put them in the fridge with some anti-fungal treatment and keep an eye on them once per week. Mine germinated earlier than I expected.
 

dkraft81

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I had some of my trident seeds germinate already, about 45 days in. Definitely keep an eye on them.
 

barrosinc

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Do you mean put them in the fridge if I were in the northern hemisphere or should I do that doesnt matter the season?
 

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I planted 600 and so far only four have come up.....I'm a little dissapointed right now.
 

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Do you mean put them in the fridge if I were in the northern hemisphere or should I do that doesnt matter the season?
Maple seeds need a period of cold in order to trigger germination. If the seeds are just lying on the ground in a cold part of the country, or if you plant them in the Fall and leave them outdoors all Winter, you don't need to do anything. However if you collect the seeds and bring them indoors (or purchase them somewhere), you need to give them a period of cold (and humidity) before they will pop. You can't just wait for Spring, plant them, and expect something to happen if they have not first had a cold spell.
 

dkraft81

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I planted 600 and so far only four have come up.....I'm a little dissapointed right now.
That sucks only a few have came up. I was planning on mid to late march for mine to start popping. I have a little greenhouse to keep them in for now, but I certainly wasnt ready to keep them indoors for an extended amount of time.
 

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