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AGS Seed Exchange: seed germination

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Started by: ian mcdonald

Go to latest contribution by ian mcdonald, 07 September 2013, 19:05. Go to bottom of this page.

Contribution from ian mcdonald 01 July 2013, 21:00top / bottom of page

Bad germination results. Out of 51 pots of seeds, from various sources, two pots have several seedlings and one pot has one seedling. Have other members suffered this poor rate? Is it the weather. Or the compost (waiting to hear from supplier). Same routine followed as usual. Perhaps the winter period will break dormancy? It is a shame to waste seed of our uncommon plants this way. What are your experiences this year?

Contribution from Martin Rogerson 02 July 2013, 07:26top / bottom of page

I've done only slightly better. About 15 out of 70. I'm blaming the weather.

Contribution from Tim Ingram 02 July 2013, 07:42top / bottom of page

I think it is difficult to conclude too much without more information of the seed sown, when sown, etc, etc. Even the most experienced seed sowers (who will tend to sow seed they have a good hope of germinating), rarely get more than 40 or 50% of what they sow coming up. The best results of all come from your own collected seed sown much earlier in the autumn. I think the long cold spring this year was quite beneficial for a lot of late sown seed that needed the typical cold period required by alpines. The biggest problem with compost is likely to be peat or equivalent based mixes which dry out much too easily, and equally get too wet. Soil based John Innes mixes with plenty of perlite or grit for improved drainage are much better. If you are new to seed sowing I wouldn't let poor results discourage you, and if you consider the poor results of seed sown naturally in Nature (inevitably), gardeners generally do remarkably well! More contributions here from members could go a long way in sharing experiences and improving results.

Contribution from Jon Evans 02 July 2013, 17:41top / bottom of page

I think it is the weather. I know a number of experienced growers who have all been complaining of the same thing - dreadful germination this year. And that is not just for alpine seed, from a variety of sources, but also easy annuals and perennials from garden centre seed, which would usually be simple and reliable.

Contribution from Tim Ingram 02 July 2013, 18:18top / bottom of page

Jon - that begs the question of whether we ever get weather that is right! Different plants respond very differently depending on their origins, and it would be very unusual to get everything not doing well in any particular year. I tend to group seed into categories that I know need different conditions, and those that don't need a cold period for example we normally sow later into spring and often using bottom heat in the greenhouse - this year this has been particularly valuable, and the warmer conditions under cover after seeds germinate is a definite advantage in many ways. I grant that many seeds will have germinated and then been seriously checked by the long cold spring, but there are always ways round this. It would be interesting to know if other member's experiences have been equally negative because it would be possible to tie this in more directly to specific weather records (we keep a day by day record of temperatures, rain etc. for example).

Contribution from Jon Evans 03 July 2013, 15:00top / bottom of page

Tim, the original question posted asked if other members had suffered a poor germination rate. I was reporting that I knew a number of experienced growers (all over the country) who had experienced very poor germination this year. All would have followed their normal sowing procedures, and no doubt all use different composts. All are used to high success rates with their methods.

The seed came from different sources, including people sowing their own seed, so that rules out Diane sterilising all the AGS seed before sending it out.

If you have soil warming to use bottom heat for your seeds that no doubt gives you an advantage, but there are a lot of people out there who have had very bad results this spring, which seems to correspond in a cheerfully non-scientific way with what Ian Macdonald reported.

Contribution from Tim Ingram 03 July 2013, 16:28top / bottom of page

I do apologise - I am being overly scientific. Our results this year are not so different from most years, but a lot of the seed we sow is home-collected or species that I have had good experience with in the past. No reflection on the skills of others is intended (and I haven't spoken with many other members about their experiences).

Contribution from Jon Evans 03 July 2013, 17:06top / bottom of page

On a brighter note I have recently received seed of several amaryllids from South Africa, including several with fleshy seeds (like Nerine) including Brunsvigia, Haemanthus and Strumaria. These seeds are always germinating in the packet when they arrive, and need light and moisture to grow on. After soaking for an hour or two to rehydrate them, I always sow them on the top of the pot, pressing them into a layer of Cornish grit.

In the past, I have struggled because my routine doesn't keep the surface of the pots damp enough, so this year I have placed them in a covered propagator on a sunny windowsill, with a shallow layer of water in the bottom of the propagator to maintain the humidity. The seeds are growing like grass.

Contribution from ian mcdonald 03 July 2013, 19:50top / bottom of page
seed germination

Hello Tim et al, The compost I use is peat free seed compost mixed with about a quarter of sand for extra drainage to help prevent damping off. I would like to use genuine soil compost but cannot find a supplier. Many will say soil based but we don,t know the proportion used, it could be a handful to a barrow load of peat. I try to use peat free to protect the rare habitat. I agree that peat in composts makes it extremely difficult to regulate water retention. It is either too wet or too dry. The species I like to grow are the unusual and difficult to obtain as plants. Most nurseries think they are not garden worthy or no-one will want them. As someone who has studied and photographed native flowers since the 1970,s I find it interesting to try to grow natives and watch what kind of conditions they prefer. I have been growing plants from seed for about 50 years. Perhaps soil could be collected from fields and sterilised for seed growing?

Contribution from ian mcdonald 04 July 2013, 13:21top / bottom of page

with regard to composts, how many people try to grow plants not normally found on peatlands, in peat? If soil is sterilised for use as seed compost, does this remove micro-organisms that are useful for penetrating seed coatings allowing water penetration and germination? Then again, if soil is not sterilised we would get a potful of "weeds." Peat contains no nutrients, they are added by the peat supplier and only last a few weeks. This is why we are told to add liquid fertilisers. Perhaps a short paper, in laymans terms please, in the Bulletin would be helpful with regard to improving our seed germination results. I, and maybe many others, rely on trial and error. I know that papers have already been written on seed germination, but does the ordinary person really understand seeds and their requirements for germination? Needs of Seeds, now that sounds a good title. Anyone interested?

Contribution from Helen Johnstone 04 July 2013, 19:58top / bottom of page

I found this interesting and reassuring. People rarely mention lack of germination so you assume everyone else's seeds are germinating like mad. I would say I have 50% at the moment but I tend to leave pots for a year or so as many will germinate after a very cold spell. I also use seed compost and preferably peat free. My understanding is that it is the mositure in the soil and temperatures that break dormancy. I also think that whilst compost may be sterile as soon as we water it the micro-organisms are added.

Contribution from Tim Ingram 07 July 2013, 08:08top / bottom of page

The sterility of composts (at least soil based ones) is only relative. John Innes (the loam base, not the sand and peat) is heated to 180°F for 10 minutes. The rationale is to kill many deleterious organisms, but valuable ones like many fungi and bacteria can quickly recolonise from resting spores etc. This is taken from 'the horses mouth' so to speak - 'Science and the Glasshouse' by William Lawrence (who was Head of the Glasshouse Department at John Innes and developed the John Innes composts). He also makes the point that heating, especially soils rich in organic material, results in extra levels of nitrogen which can inhibit seed germination (seed composts have much lower levels of fertiliser added for this reason). Elsewhere he makes the point that 'the importance of the compost cannot be overrated', which I am sure we would all agree with but be less sure how to determine this. The John Innes Composts were carefully formulated on the basis of research, but nowadays the imperatives are more to do with light composts supplemented with slow release fertilisers for 'point of sale appearance' of plants; plus a strong lobby against the use of peat - the alternatives are probably based more on this sensitivity often than they are on careful scientific studies like those carried out at John Innes many years ago (I am sure there are many honourable exceptions and these are the ones to search out when sowing seed). This is a long answer to a simple question but that is the way scientific enquiry works, and it does work by repetition and comparison of results which is why individual experience on a website like this can be so valuable. (I do have the horrible sensation of 'teaching my grandmother to suck eggs!' - but my grandparents did run a market garden so they probably taught me something too).

Alpine seed is very different in its requirements from the majority of seed that Garden Centre composts have been developed for and I always stick with soil-based mixes, supplemented with grit or perlite (the latter really helps when separating and pricking out seedlings). There are still a few manufacturers that produce John Innes according to the original formulations. I'm not sure how many spouses might allow it but in the absence of any other way of getting sterilised loam, Lawrence recommends a kitchen saucepan with an inch of water brought to the boil and then filled with soil and simmered for 15 minutes! Or suspend soil in sacking and steam. Perhaps there is room for Jamie Oliver here!

Contribution from ian mcdonald 24 August 2013, 10:27top / bottom of page

An update of seed germination. I now have no germinated seed in any pots. I wrote to the supplier of the compost to see if they had changed the formula of the compost. I received no reply. The compost is supplied be the Irish Peat Board. I bought the compost as it was called "vital earth." Close inspection of the compost revealed only very small pieces of soil among composted material. Can anyone tell me of a supplier of seed compost which is 100% soil?

Contribution from John Good 25 August 2013, 20:16top / bottom of page
What about the quality of the seed?

Nobody has yet mentioned that the very wet season in 2012 probably resulted in much seed not receiving the ripening that it would be expected to receive in a 'normal' summer, or especially a 'good' summer such as we have had this year. If seed is collected before it is fully ripe, as a lot probably was last year, and then perhaps not dried adequately before storage, that could explain a lot of the poor germination rates experienced over a wide range of plants this year. I would expect much better germination of seed from the AGS exchange next season.

Soil-based composts

I agree that soil-based composts are much better for slow to germinate seeds (such as many alpines) than those comprised mostly or solely of organic matter, whether it be peat or something else. I am lucky in that I can get J. Arthur Bowers John Innes composts locally, as I have found them to be pretty consistent and nice and open in texture. Clagginess in soil-based composts, especially those to be used for sowing seeds, is to be avoided at all costs. My supplier stores his JI compost bags under cover so that the contents remain reasonably dry, be very doubtful about compost in bags that have been stored in the open for any length of time. For seed sowing I mostly use equal parts of JI No. 2 and either silica grit or sieved perlite, which in the latter case has been moistened in the bag for two reasons (a) to avoid me inhaling a cloud of perlite dust, which can't be good for the lungs, b)because damp perlite mixes in much better with the JI than the dry product.

Contribution from ian mcdonald 01 September 2013, 10:51top / bottom of page

Thanks for that John. Does anyone know where Arthur Bowers JI composts are obtainable? Most garden centres in my area S. Yorks. seem to supply the "popular" brands which are the "flavour of the month." Seed in my small garden seems to be more available this year and I am collecting for the seed exchange now. I am particularly interested in native species although I do grow a small variety of alpines from other countries.

Contribution from Tim Ingram 06 September 2013, 22:47top / bottom of page

We also use Arthur Bowers JI compost which seems very good, but much less available than it used to be. It might be worth considering mixing your own compost - our local B & Q has sterilised loam for topdressing lawns, and the formula for JI seed compost in Lawrence's book is 2 fibrous medium loam (old stacked turf is ideal but would need sterilising!)/1 granulated peat (fine grade bark used for propagating might be just as good)/1 sharp sand (quite coarse, up to ??in). Lime (or chalk) should be added to bring the pH to just the acid side of neutral (Lawrence specifies pH 6.3, though I wouldn't have thought this is really critical so long as it's around neutral). The loam should contain enough nutrients initially for young seedlings and they can easily be fed gently as you water when they begin to grow away. We generally add about 20 to 30% perlite to open the compost up more because even JI compost can become too compacted over the long time that many alpines take to germinate. Unless the seed is very small we topdress with chick grit which keeps weeds and liverwort at bay. For quicker germinating seed some growers top dress with vermiculite which keeps the surface moisture level high, but is not so much use for most alpines which require a winter cold period. The exceptions to this would be ericaceous species which as mentioned earlier are best sown in a low nutrient ericaceous compost (and we usually add sand which helps wetting the compost - peat on its own always seems difficult to keep uniformly moist; it's either too wet or impossibly dry). I haven't had much experience growing such plants but use the same technique as with ferns and ramonda, i.e: sterilising the compost with boiling water, pouring through a paper towel over the pot, and then sowing the seed or spores and keeping in a propagating box. The seed is usually so tiny that it can't be covered with grit or compost, though a scattering of vermiculite might well be effective.

I hope this might help - it's very frustrating when seeds don't germinate well, but when they do it must be one of the most exciting aspects of gardening of all. There is a very good and much more informative article by Vic Aspland in the AGS Bulletin Vol. 80, p. 40, on John Innes composts, and the experience of several very good growers using them, which would be well worth referring to.

Contribution from ian mcdonald 07 September 2013, 19:05top / bottom of page

Thanks Tim, useful advice as usual. Surprising how many attempts it takes to get it right.

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