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Thread: Warm and Cold Stratification and Dark period

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    mcmcnair's Avatar
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    Warm and Cold Stratification and Dark period

    Ok so there has been a lot of discussion around Nepenthes seeds and how to do it and I know there are a bunch of different threads on that, but I wanted to inform you all on what I've learned as a horticulture major and my theories as to how it relates to Nepenthes and their seed germination requirements.

    One of the first things I learned about seed germination is cold versus warm stratification. Some plants require a cold stratification, meaning their seeds need to be exposed to at minimum a few weeks of 40F. Cold Stratification means a period of moisture and cool temperatures. This applies to some Drosera seed, and Sarracenia seed. In order to cut down on mold I alternate the seeds between the freezer and the fridge every week until the strat period is done (4-6 weeks depending on what you're stratifying). Some plants require a warm stratification, I believe that some nepenthes might fall into this category. For instance, I have never heard of anyone getting nepenthes seed germination within a week or maybe two after sowing their seeds (please correct me if I'm wrong ). My theory is that once the seeds are exposed to moisture and the temperatures they need to germinate they begin stratifying. In my experience, which is very limited I'll admit, Nepenthes seeds germinate within 4-12 weeks after sowing. I think those first 4 weeks are a warm stratification period.

    As for dark periods as a germination requirement. It is well known that in some shade dwelling plants such as Cyclamen, seeds must be exposed to a period of dark stratification (exposure to low light levels and moisture) in order to germinate. While some seeds will germinate without the dark period, germination rates are much higher when the seeds are exposed to darkness. I believe that this could apply to Nepenthes. Some people I have talked to claim that they do not get germination without a dark period of around 7-10 days. While others say the whole idea of a dark period is a bunch of melarchy.

    And in conclusion, some basic general things that I've heard people say that are incorrect:
    1. Storing seeds in a fridge or in a bag is not the same as Cold Stratification.
    2. Stratification does not necessarily mean exposure to cold and moisture.
    3. Exposure to darkness is a suitable substitute for stratification
    4. Nepenthes need a cold stratification period
    5. Exposure to any sort of cold temperatures will harm nepenthes seed. (Perhaps prolonged exposure but definitely not a brief exposure)
    6. Store your nepenthes seed in the fridge if you can't sow it immediately upon arrival (I'm not 100% sure on this)
    7. Nepenthes go through a dormant period.

    These are just things I have picked up on since I started college a few years ago and since joining the forums. Thanks for reading!
    NCSU's Carnivore Nut
    Original President of the CCPS & Co-Founder
    Mason M.
    My Growlist

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    Cthulhu138's Avatar
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    I've been growing Nepenthes from seed for years now and have germinated thousands of them. I get terrific germination rates and have never given them a dark period. They simply do not require it.

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    i like the part where you said melarchy

    good thread, i had to learn these terms in botany class. fun fun fun

    i find it pretty fascinating how some plant seed will not germinate at the same time or even the same year when exposed to the same ideal conditions. Some will germinate but others will remain dormant and germinate later in the season or the following grow season. All this to increase the chances that some of their offspring will survive in the long haul.

    may not apply to many or any CPs but it holds true for many others ^

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    mcmcnair's Avatar
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    thanks for the input. Like I said I am merely theorizing. Would be a good research project for someone though
    NCSU's Carnivore Nut
    Original President of the CCPS & Co-Founder
    Mason M.
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    I'll test this theory out! I have two different amp varieties coming. Ill have one pot of each variety in bright light and one pot of each variety will have a dark period of, lets say 10 days, i'll keep them all in the terrarium so they all have the same temp. conditions. And in the coming months ill keep track of germination dates and numbers. Anything I'm missing? Then maybe someone who is better at the demon program SPSS can help me enter all the data
    Travis

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    mcmcnair's Avatar
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    just use Excel and keep a manual tab of the number germinated each week in each pot.
    NCSU's Carnivore Nut
    Original President of the CCPS & Co-Founder
    Mason M.
    My Growlist

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    DonH's Avatar
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    Quote Originally Posted by mcmcnair View Post
    For instance, I have never heard of anyone getting nepenthes seed germination within a week or maybe two after sowing their seeds (please correct me if I'm wrong ). My theory is that once the seeds are exposed to moisture and the temperatures they need to germinate they begin stratifying. In my experience, which is very limited I'll admit, Nepenthes seeds germinate within 4-12 weeks after sowing. I think those first 4 weeks are a warm stratification period.

    As for dark periods as a germination requirement. It is well known that in some shade dwelling plants such as Cyclamen, seeds must be exposed to a period of dark stratification (exposure to low light levels and moisture) in order to germinate. While some seeds will germinate without the dark period, germination rates are much higher when the seeds are exposed to darkness. I believe that this could apply to Nepenthes. Some people I have talked to claim that they do not get germination without a dark period of around 7-10 days. While others say the whole idea of a dark period is a bunch of melarchy.
    If I recall correctly, Nepaholic posted that he was able to consistently germinate nepenthes seeds in less than 2 weeks.

    I've also documented germination of N. attenboroughii seeds within 13 days in a recent thread here. The attenboroughii seeds were place in a propagation tray in lowland conditions (80F and 75% humidity) and under fluorescent shop lights (6500K tubes) immediately after being sown. So far, I'm getting over 50% germination after 3 weeks.

    I'm also starting to see N. lowii sprouts in less than 3 weeks under the same conditions with no dark period.

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