Some Thoughts on Difficult to Germinate Seeds

Over the years I’ve purchased my fair share of seeds that didn’t germinate. Just about all have not been annuals and none have been vegetables.  Often they have been trees and native herbaceous species though not necessarily native to my region.  Rarely have they been cultivars.  I followed the instructions to the letter: x days of cold stratification in the refrigerator and plant in starting mix with bottom heat at a certain temperature range for y days.  I even tried winter sowing them but that didn’t work either.  At first I thought that the seed supplier had provided poor seed but after purchases from a fair number of different seed suppliers, I realized that probably wasn’t the problem.  And so I concluded that it was Mother Nature at work – sometimes you got lucky but mostly you didn’t.

Last year, after another round of disappointing failure, I more or less gave up and didn’t order seeds this year if the indication has hard to germinate or cold stratification required.

One of the plants that I’ve been interested in growing is hawthorn.  There are a number of places where you can buy seeds of the different Crataegus  varieties – FW Schumacher and TreeHelp.com.  Last year I ordered 4 varieties of Crataegus and not a single one of the total 160 seeds germinated.  I followed the germination instructions exactly and I did research to see if there was anything that I might be missing.  I found published papers that used different variations of cold and warm stratification. One stated that:

Propagation of hawthorn by cuttings is difficult at best, and propagation from seed can be disappointing if the proper sequence of treatments is not known and followed. Consistent year-to-year availability of seedlings is dependent upon proven workable seed treatments.

And so I determined to sow no more hawthorn seeds unless they were gifted to me or swapped.  But I didn’t entirely give up on hawthorn.  I did find a seedling source – Lincoln Oakes Nursery –  for a particular hawthorn that I was looking for – Arnold Hawthorn “Homestead”  (Crataegus arnoldiana). It’s supposed to have relatively large edible fruit. There was quite a bit of back and forth because they have both a wholesale and retail operation that I wasn’t aware of  but all web links point to the wholesale nursery that doesn’t have a functioning shopping cart.  Eventually, I got an order form which I emailed back to them.  After quite a while, I received a phone call about the order.  During the course of the discussion, I was able to get the website confusion sorted out,  get to the correct website and place an order online while they were still on the phone.  At the end, while chatting a bit, I asked if there was anyone that I could talk to about propagating hawthorn from seed.  Sure, I was told, The nursery manager’s standing right next to me. I’ll put him on.  I briefly explained how I’d been having no success with the techniques I’d been trying and asked him how they were having success that allowed them to sell large seedling quantities.  He said that the previous manager had used the techniques that I was using with 40% or less success but that he didn’t use those techniques.  He simply planted the seeds in pots outside and came back 18-24 months later to seedlings.  He said his success rate was around 90%.  I looked back at some of the research that I had and noticed that they did talk about the long dormancy but were trying to find ways to successfully break the dormancy.  And their conclusions that hawthorn was difficult to propagate have become horticultural wisdom that is repeated over and over whenever you read about hawthorn seed germination.

I suddenly realized that once again, here was man trying to control Nature rather than just letting Nature get on with it.  In some instructions that came with some Blackthorn, Sloe (Prunus spinosa) seeds, notoriously difficult to germinate, that I ordered this year and just received, there is the line “It has been found that fluctuating pre-treatment temperatures can give the best germination results and I myself have had excellent results by keeping the mixed seeds in a cold shed through the winter for the cold storage of their pre-treatment and allowing the temperature to fluctuate naturally.”  And there it was – my Aha! moment: Naturally = winter sowing but over two winters as Lincoln Oakes was doing!!!!!!!   Two years means a lot of tending especially during the summer when the seed mix will dry out.  And there’s the distinct possibility of the seed rotting because of too much moisture somewhere during that time.  After a bit of thinking about the problems involved, I came up with a process that I’m going to try that replicates Nature as much as possible but in a way that reduces some of the randomness.

I’ll sow seeds in pots filled with ProMix BX.  That will provide the seeds with a tailored, proven germination mix that  stays moist without water-logging and has Mycorrhizal fungi to aid root development after germination.  I’ll cover the pots to keep the snow from building up and giving a moisture problem when it melts.  In the spring, I’ll sink the pots into the ground in an area that gets early morning or late afternoon sun and cover them with a plastic bag to keep the moisture in as well as weed seeds and animals out.  Being out of the direct sun will keep the greenhouse provide by the plastic bag from overheating.  To avoid possible rotting, I’ll add no water to the pot but rely on whatever moisture is inside the bag and in the soil mix.  I’ll be able to see moisture beading on the inside of the bag which will tell me that there’s enough surface moisture to start germination.  If there’s no beading within the first few hours of being covered, I’ll remove the bag to do a very light misting of the soil and then re-bag the pot.  I can check one a week or so as I move around the garden doing other things.  Hopefully, this benign neglect approach to letting Nature determine the germination cycle will produce the same kind of results with any difficult-to-germinate herbaceous and woody perennials that Lincoln Oakes has in its nursery programme.

In reflecting on this essay, I’m struck by a couple of questions. Why do we think that fixed temperatures are better that the fluctuating temperatures during germination?  Why do we think that we can do better than Nature which implies that Nature is wrong?  That kind of thinking has taken us down and continues to take us down so many wrong paths, many of which are increasingly looking like dead ends at best or, at worst, lead over the cliff.

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9 Responses to Some Thoughts on Difficult to Germinate Seeds

  1. Nicolas M. says:

    We already discussed a bit about that by mail, but i think the whole thing of reductionnist science is to have known variables to control and adjust to see what this variable is responsible for. Letting the nature do the job does not fit this paradigm. The result have to be predictible too. Not knowing if the seed will sprout this year or one year letter is not modern science, it is cave painting for them 🙂

  2. Garden Prince says:

    There are some things you need to know about 1. seed sellers and 2.germination requirements for specific plant genera/species.

    1. Some plant species have a short viability and cannot be stored for very long or can only be stored well under cold and moist conditions. Magnolia, Daphne, Asimina, Quercus and some Acer species are examples of plant groups that fall into this category. You would guess that seed sellers know this fact and treat these seed group accordingly. However, many commercial seed sellers sell old and dried out seed that won’t germinate in a thousand years. My guess is that for many companies it is too much work to store these kind of seeds the right way. I also have the feeling that many seed sellers don’t throw away their old seeds because most of the time they bought these seeds themselves and throwing away old seeds is to them equal to throwing away money. The problem for the buyer is that that you can’t see how old a seed really is. And another problem about which the buyer knows mostly nothing: how is the seed treated by the original seed collectors?

    2. Many plant genera (especially annuals, vegetables and many perennials) germinate relative easy from seed. There are however plant species that germinate only after a certain treatment or pattern. Some seeds will only germinate after receiving a pattern of warm period —> cold period —> warm period (Stewartia, Davidia and Halesia for example). Others need a cold period of 1, 2, 3 or even 4 months to germinate (many shrubs and trees from the temperate regions).
    Norman Deno has done extensive research on the specific germination requirements for many plant species. His book (and two supplements) about germination is now in the public domain and can be found at this link: http://naldc.nal.usda.gov/download/41278/PDF . The only drawback to this book is that Deno got many seeds from commercial sellers and had no knowledge of their age or where they were collected.
    Many hawthorn species (not all!!!) require first a warm stratification period of about 3 months, followed by 3 months cold stratification. This can be done the natural way by placing the seeds outside in late autumn and winter and let the natural elements do their work. This will take a minimum of 1,5 years before any germination takes place. You can also place the seeds together with moist vermiculite or potting compost in ziplock bag and place it somewhere warm (room temperature) for 3 months and after that you place it in the vegetable compartment of your fridge (NEVER in a freezer) for three months. After these warm/cold periods you can sow the seeds at warmth. Vermiculite or slightly moist compost is absolutely necessary otherwise the stratification process is not going to work. However: it is very important that the vermiculite or compost is not too wet otherwise the seeds will rot or get mold. This is also true if you place the seeds outside so add enough grit or sharp sand to the sowing medium.
    We know that for many members of the Rosaceae (like hawthorn) germination is erratic. So don’t expect that all your seeds will germinate after the initial warm/cold stratification period. Sometimes only a few germinate after the first warm/cold stratification period and a second warm/cold stratification period is necessary for get futher germination. And even then: as in nature many seeds will not germinate simply because of embryo defects, fungi and rot.
    You get the best results with hawthorn with fresh seeds that are thoroughly washed. Only buy them when you know the seed is absolutely fresh. There are gardening forums where you can place an add for seeds and this offers the best chances for obtaining fresh hawthorn seeds.

  3. Traci says:

    I gathered some hawthorn seeds from a local university today. Obviously I didn’t realize what a problem germinating them could be. I want to thank you for writing this post. As I was researching on the net I was wondering why I couldn’t do almost what your proposing here.
    I think sometimes people forget we love plants because we love nature so, why not let Mother Nature help out ?
    Traci

  4. Kean says:

    Try feed fresh but ripened haw berries to hens, then plant the seeds after they came out the backend of the hens.:-)

  5. readrobread says:

    Great information here Mike. I’ve followed a similar path with trying to germinate seeds that require a cold period. My aha moment was like this: I planted some beach plum seeds in the fall, in pots (so I could find them again), then sunk the pots into the ground (actually just taking out some sod from a lawn to do so). The next year – nothing. One year following, mid summer (after absolutely no care from me – and they were just in soil, not a potting mix) I thought it was about time to put away these submerged pots, and I noticed that about 80% had beach plum seedlings in them!

    Now beach plums are excessively tough trees – they remained green and put on new growth despite being in pots the entire rest of the season, and only periodically being watered – and that soil got HARD and dry. But it really pushed me towards natural germination over winter (or two winters).

    So – it sounds like my method is actually really similar to yours. I picked up an old window with frame, and dug a whole just a bit smaller. Inside that hole are pots with a potting mix and various seeds that require cold stratification. I left the window on all winter (largely for squirrel protection), and when it got warm in the spring, I switched to an old screen door insert with a wooden frame the same size as the window. I had quite a bit of success, but many pots still show no sign of anything. Just the other day, I switched to an a-frame with screen on all sides to let some of the taller stuff have some space. At some point, hopefully by the fall, I’ll transplant out the stuff that’s large enough, and leave all the remaining pots for another winter, and shift in some other seeds. It’s worked well enough that I’m going to make a second set-up with another window I have that’s the right size.

    It sounds like you desire the same thing as me: just getting the genetic material of some of these plants on site, so you can play with them. Once we’ve got specimens of some of these plants, we can use our own seed – which we are certain of the freshness of…

    I planted Crataegus schraderana (from Gardens North) last fall – so I guess I’ll wait for NEXT spring to find out if those hawthorns will germinate.

  6. Nils H. Dahlberg says:

    Sheffield seeds is a company I can recomend. I have had no problems with nuts and seeds to germinate, but crataegus is a special ‘family’ so try to get hold of fresh seeds with fruitpulp and store them washed in moist sand in the fridge. From autumn to spring change the seeds from fridge to roomtemperature 3-4 times. By doing so Crataegus seeds germinate with average 50 %.

  7. Bill A says:

    Hi Mike, I like your post. I like the Hawthorn tree and have been trying to germinate many seeds with no success. I would like to grow some seedlings to train as bonsai. I am going to try again. This time I will stratify the seeds in pots placed in a protected area outside or in a cold area where the natural variations of winter and spring temperatures will hopefully be effective. I must be patient, since hawthorn seeds may require a second cycle of stratification to germinate. As a gardening and tree enthusiast I always love the challenge and anticipation.

    Regards,

    Bill A (Montreal)

    • MikeH says:

      Hi Bill,

      I’ve not tried to propagate anymore hawthorn seeds since I’ve been gifted the varieties that I was looking for. Nonetheless, reflecting on Michael Dirr‘s instruction that soaking in acid (sulphuric or hydrochloric) is required, it seems to me that we may be imposing on Nature rather than working with her. Reflecting on what Nature is doing with hawthorn seeds, it may be that the seeds cannot be allowed to dry out as is the case with pawpaw seeds. So buying seeds may tend to a low germination rate rather than a higher rate that might result from extracting seeds from fruit and planting in pots to let Nature control the schedule.

      What variety of hawthorn are you working with?

      Regards,
      Mike

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