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Principles of seed sowing

Discussion in 'General Gardening Discussion' started by PeterS, Jan 23, 2012.

  1. PeterS

    PeterS Total Gardener

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    I have just sent some seeds to a GM member, who says she has not had that much experience. So rather than trying to send instructions to her, I thought I would open it up as a thread. What follows is purely my method. There is no single right way, many people will use slightly different methods with just as much success.

    A few principles are worth keeping in mind:-

    All seeds need both moisture and air to germinate. So if your compost excludes air by being too solid or too wet you will have a problem. By covering the seed you will maintain it in a moist environment, and all seeds contain enough energy for the emerging seedling to push its way up through the compost. Big seeds contain more energy and so can be buried deeper than small seeds. The general rule is to cover the seed by about its own thickness of compost. That very difficult to judge so I sprinkle compost on top a bit unevenly, leaving some seeds well covered and some hardly covered - the chances are that some seeds will be happy. :D Most seeds don't need light to germinate, but some like Salvias do - so they need to be left uncovered.

    You have to think how a seed germinates in the wild in its native environment, and copy that. Many seeds germinate in spring because that gives the plant a long season to get established before winter. How do they know its spring? Well they usually feel its spring when they warm up. So many seeds like heat to kick start them into growth. Once they have started growing they can't get back into the seed shell - so they are generally happy to carry on growing at a lower temperature. But some seeds like to germinate at cooler temperatures than others so you must check the temperature requirements.

    Don't use garden soil - it will have lots of unwelcome seeds in it as well as being too heavy to make good seed compost. I use a mixture of 2/3 multi purpose compost with 1/3 sharp sand. Perlite is probably even better than sharp sand as its light and holds water, but you don't see it for sale that often. The purpose of the sand is to help drainage and leave pockets of air. Compost by itself can get very soggy. I usually sieve the mixture (when I remember) to remove the lumps

    If you want lots of plants - use seed trays. But if you only want a few plants use a small square pot. The advantage is that pots are deeper and hold more compost and hence moisture, and you can fit 15 quite large square pots into a big propagator, rather than just two full size seed trays. Square pots obviously fit better than round pots. Half size seed trays, can be divided into two with a plastic label if you want more plants.

    I go by Christopher Lloyd's (Great Dixter) rule of thumb. Don't start sowing flower seeds till 1st March. And for tender annuals such as Cleome, Tithonia and Cosmos its often better to wait till 1st May. The reason is simple. You can easily germinate seeds well before with a heated propagator inside the house, but what do you do with them when they get bigger. There won't ge enough light or space indoors for them, and it will still be too cold to put them outside. If things like Cleome and Cosmos get too cold outside, even if its some way above freezing, they can go into a sulk and never fully recover. Obviously if you have a greenhouse or other suitable facilities you can bend these rules. Although May sounds late, the temperatures and light levels are so much higher then that tender plants tend to catch up quite quickly.

    When it comes to sowing, fill your pots or seed trays with the compost mix and water well. Its quite a good idea to use boiling water, as this tends to sterilise the compost, but you must let them cool down and drain before the sowing. Sow the seeds on the top of the moist compost, then sprinkle a little more compost on top of that. The compost on top will probably be dry so you need to wet it. Don't pour water on, you could wash the seeds down too deep into compost. I spray water on top.

    In fact I don't spray water, I make up a dilute copper solution, which is an anti fungal agent, and use that. I still use Cheshunt powder diluted as instructed on the tin - actually I use it more dilute. Cheshunt powder is now illegal and withdrawn from use. The reason, I have gathered from several sources, is not because there is anything wrong with it, but that the EU has forbidden it because new rules came in recently stating that all garden chemicals will be made illegal unless they pass through a rigorous (and expensive) testing procedure. Because Cheshunt compound is generic (ie is owned publicly for all to use) no one is prepared to spend the money getting it passed for 101 other companies to be then free to make it. It has been replaced by another copper based compound made by Bayer called "Fruit and Vegetable Disease Control". This is patented and owned by them, but reports say that it is not as effective as Cheshunt.

    I then put the pots that have been sowed into a heated propagator and cover it with a lid. You don't need a propagator - you can always improvise with any transparent container that is covered. And you don't need it to be heated if you have it in a warm room. Because the propagator is covered it will lose very little moisture, so there is no need to give it any more water for several weeks. I just spray it occasionally with my dilute copper solution. This replaces the very small losses of moisture and more importantly acts as an anti fungal treatment.

    Once the seeds start to germinate you can slowly start to let air in by slowly removing the cover. To prevent seeds 'damping off', ie dying from fungal infections, I continue to spray regularly with the copper solution. By using a very dilute solution, I don't worry about over spraying. So my spray doubles up as a watering system as well. Once the seedlings start growing well you can remove them from the heat. However most seedlings will continue to enjoy the heat as long as they get plenty of light. Too much heat and too little light will make plants grow spindly and weak.

    You can pot seedlings on at any time that they are big enough to be handled. But most people wait till they have two sets of leaves - the cotyledons and the first true leaves.

    Most seeds are straightforward, but be aware that some need special treatments, such as pre soaking, or a prior cold treatment. Your seed packet should give you full instructions - otherwise there is always the internet.
     
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    • chitting kaz

      chitting kaz Total Gardener

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      thanks peter
      that is great for us begginers :dbgrtmb:
       
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      • lazydog

        lazydog Know nothing but willing to learn

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        well written Peter:dbgrtmb:
         
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        • roders

          roders Total Gardener

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          :) Good sound advise as usual Peter.
          It's that time of year,we're all raring to go.....:yess:
           
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          • Angelina

            Angelina Super Gardener

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            Peter, thank you for your all-round and knowledgeable approach to my sowing enthusiasm! I had no idea that I had to ensure air running through the mixture (for instance). Fortunately, I have some perlite and trays. Sand, too. I will only have to buy some appropriate seed compost.

            My cleome of last year was a failure. I received seedilngs from a friend and collected seed. I'll start them later this year, indoors first, and then will move them in the greenhouse.

            I guess I will have better success with 'standard' seeds than with the 'difficult' ones. I was daring enough to order roses, rhododendrons, blue poppies and ferns. :scratch:The biggest problem is having no experience of my own and 'desperately' trying to catch up by reading from more than one source. This gets me into confusion. :rolleyespink:
            Luckily, I have local people whom I can bother with questions about most of these.

            I'll start and I'll learn from my mistakes. (The only positive statement I can make...[​IMG])

            I've copied your invaluable introductory post, and I'll follow this thread for development.
            Thanks again!
             
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            • PeterS

              PeterS Total Gardener

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              Angelina - all plants need oxygen. But it was a long time before I realised why.

              If you or I need energy, we eat bread and sugary items. Our vascular system carries these carbohydrates and sugars to the parts of the body where they are needed. They are then burnt using oxygen to release energy and build tissue.

              Remember that we share half our DNA with plants, and they do the same thing. They are not good at shopping expeditions, so they make their own sugars and carbohydrates by photosynthesis. They do this in the leaves using sunlight, carbon dioxide, and water and releasing oxygen.

              As with humans, the plant's vascular system then transports these sugars to where they are needed, such as in the roots. There they are burnt, using oxygen, to give energy and build tissue.

              If you overwater a plant you replace the air pockets in the soil with water, so no air is available. Without air the roots cannot live - literally they drown just like humans. With no roots the plant cannot absorb water from the soil - so it dies of dehydration! That's why the symptoms of over and under watering are often the same. :D

              This also explains why plants mostly give off oxygen during the hours of sunlight. But the action of burning the carbohydrates carries on 24 hours a day, so at night they use oxygen and give off carbon dioxide. This allows plants to grow as much at night as they do during the day.

              A seed comes prepacked with carbohydrates, which it must burn to produce the energy to make the first leaves. So a seed also needs oxygen from day one.
               
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              • HarryS

                HarryS Eternally Optimistic Gardener

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                Superb seed sowing guide Peter. I like to understand and comprehend why we do this , or should not do that in gardening , rather than following instructions blindly in a "monkey see , monkey do" mode . Your post covered quite a few points I was unsure of . :dbgrtmb:
                The best source I have found for perlite ( and vermiculite ) in the volumes I use, is Wilkos . At about £3.50 for 10 litres ( It is £8 for 10 litres in my local gardening centre !!! Robbing gits :D ) I mix the perlite with my seed compost on the trickier low germination seeds and then a thin sprinkling of vermiculite , a quick spray with whatever damping off compound is legal then sit back and wait . I don't know about everyone else, but it is still a thrill when you see your first seeds of the season germinating :dbgrtmb:

                PS Admin can this thread be made a sticky?
                 
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                • daitheplant

                  daitheplant Total Gardener

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                  Seeds also need WARMTH to germinate.:dbgrtmb:
                   
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                  • PeterS

                    PeterS Total Gardener

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                    Thanks Harry. Yes, like you, I like to understand the principles of what is happening and why plants act as they do. Actually, if you can understand one principle - it often saves having to remember a 1000 details.

                    People always wrote about Perlite, but I never saw it on sale for years, except perhaps for a very small bag at a huge price. Then I went to Gordon Riggs Gordon Rigg Garden Centres at Rochdale one day and saw 80 litre bags for £16 - so I bought 2 bags. Now I have so much I don't know what to do with it. :cry3:

                    I would recommend a trip to either of the Gordon Riggs sites. They are cheap and chearful. but the prices are very reasonable, and I managed to buy a few unusual things like a small coffee bush for 0.86p, a small Hibiscus for 0.86p, Bougainvillea for £2.25 and others.
                     
                  • longk

                    longk Total Gardener

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                    This should deffo be a "sticky"!
                    Thanks!

                    One other important element though - patience.
                     
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                    • Angelina

                      Angelina Super Gardener

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                      Perfect! :thumbsup:
                      I like this 'narrative' approach to the principles, as it guides you to understand a set of possible situations by 'typology'.
                      Also, narrowing the meaning of air to 'oxygen' makes it even clearer. :)

                      It is a worthy analogy, my plants really love it when I work around their roots, to ensure good ventilation and circulation of water and nutrients. Roses and hydrangeas respond very well to such care. But as roots are ramified, they just give you an idea how to handle them best.

                      Whereas, a seed is compact and encapsulated. I couldn't think of 'air' by just looking at it. :heehee:
                      Your explanations will trigger a qualitative difference in what I do this season. :thumbsup:
                       
                    • Angelina

                      Angelina Super Gardener

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                      Started 'cooking' them. :D
                      Datura in 80/20 sand/compost mixture, ready to be sealed and thrown out in the snow.

                      [​IMG]

                      Compost and perlite ready in containers, so's the fungicide spray. At the background: brugmansia and baptisia australis, scarified and soaked (floating rather) in water, a bit below 40 C (tested 'to the touch' :D) and sealed in a thermal bag to be placed on the radiator.
                      [​IMG]

                      I owe all these seeds to Peter, 10X! Never treated any seeds before, I was clumsy. I read that datura and brugmansia were toxic.'Use gloves', I decided. Put them on, washed my hands once, and the gloves got sticky...:heehee:

                      Then I remembered how I handled my harvest of seeds while naming and packing them for the winter: with a postcard.
                      I use a nice big folded Christmas card to spread the seeds on, then fold it a bit, so they line up in the middle and can easily be counted (if large enough) and then 'poured in' any container - a bottle in my case.
                      Haven't touched them at all.

                      I find this whole thing fun! :D
                       
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                      • longk

                        longk Total Gardener

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                        Just wash your hands after handling Brugmansia or Datura - they are only toxic if ingested.
                        The foliage may cause rashes for some after contact too.
                         
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                        • Angelina

                          Angelina Super Gardener

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                          I found no datura thread, so I'm just using this one to report the progress. Daturas were cold-treated under the snow for about a month and a half.

                          None of them showed until early June! Nine in total germinated in about 2 days and grew up so fast that I managed to prick out only 4 before transplanting the whole lot in the garden.

                          Now I have 2 groups, each has one plant overshadowing the rest of the members and budding. I was expecting purple double-flowered daturas, but the first I will have is this one:

                          [​IMG]

                          I feel happy about the whole experiment!!
                          PeterS, you have all my gratitude! :ThankYou:
                           
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                          • PeterS

                            PeterS Total Gardener

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                            Angelina - I am so glad they have come up. Once germinated, yours have grown very quickly.

                            I have a couple at the same stage. I too was expecting them to be purple. But I have had so many Datura seeds over a period of time from kind people on this forum, that they have got a bit muddled. Like mine, yours looks as if its going to be yellow - but I think its going to be white.
                             
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