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Tomato Grafting

Discussion in 'Edible Gardening' started by JWK, Feb 21, 2013.

  1. JWK

    JWK Gardener

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    In recent years I’ve noticed more and more grafted vegetable plants appearing in Garden Centres and on the web. Initially I thought this was an expensive fad, but when I found out that commercial organic growers were using grafted plants I thought it was time for me to try them.

    The aim of grafting tomatoes is to combine a vigorous, disease-resistant rootstock with another variety (the scion) that may not have disease resistance but does have tasty fruit. I suffer with soil borne diseases, if I don’t replace my greenhouse soil the follow on crop of tomatoes is spindly, weak and low yielding, so all the more reason to try them.

    Ready grafted plants are available in a limited range of varieties, I wanted to grow my preferred tastier types, so that led me to try a DIY approach growing from seed. Also ready grafted plants are quite expensive, another reason to grow them from seed.

    The big disadvantage of DIY grafting is the extra time taken to learn and apply the techniques.

    I started January 2012 having watched a few videos on YouTube showing the procedure. It is quite fiddly and a fair amount of dexterity is needed, something I was lacking in. As the rootstock seed is relatively expensive I initially practiced using some surplus seeds. Whilst this helped me develop a technique that suited my banana fingers I also learnt a bit about timing and matching up stem sizes.

    During March & April I was sowing batches of the actual Arnold F1 rootstock (from Moles Seeds) and different scions and developing my technique.
     
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    • JWK

      JWK Gardener

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      I initially tried growing both rootstock and scion seedlings together in same pot as described at Step 2) here:
      http://www.molesseeds.co.uk/flower_and_vegetable_seed_store_uk/zz640_grafting_tomatoes.pdf

      This method did not work for me, the tension between the two plants pulled the grafts apart no matter what I tried.

      I used a variety of techniques to hold the graft together and different grafting joints (45 deg cuts and wedge/splice). The grafting clips only worked if the rootstock and scion stems matched exactly, otherwise the joint wasn’t gripped tightly and the scion slowly died:

      IMG_6201.JPGIMG_5955.JPG


      I tried sticky taping the graft but the stems were too easily damaged and the tape didn’t stick.

      Eventually I found silicon grafting supports in a GC which worked well for me:
      IMG_6300.JPG

      Once the graft is made the plant needs high humidity and reduced light for a few days (otherwise the scion wilts and dies). Poly bags were no good as it’s very difficult to inspect, pulling off the poly bag usually resulted in separating the graft!. Eventually I settled on a couple of big plastic storage boxes to fully enclose the plants, then sprayed twice a day.
      The plants don’t grow during this high humidity/low light phase so the graft procedure sets them back by a fortnight. Here’s my ‘Delicious’ variety, with two grafted plants on the left and non-grafted on the right showing difference in size at this stage:

      IMG_6203.JPG
      The non-grafted plants had an extra two weeks under grow-lamps, that’s why they looked healthier. In the long run however the grafted plants caught up and overtook the normal plants in terms of size and produced ripe fruit first.
       
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      • JWK

        JWK Gardener

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        PLANTING:
        When it comes to planting I found another disadvantage of grafting. Normally I would ‘deep plant’ tomatoes, plunging them into the soil right up to the first truss. This encourages roots to develop on the buried stem and increases the vertical space for extra trusses before the plant hits the roof. You can’t ‘deep’ plant a grafted plant since the splice needs to be above soil level, otherwise the scion will send out is own roots, negating the advantage of the rootstock’s disease resistance and vigour.

        In the long run this was not such a problem. When I dug up my tomatoes at the end of the season, the grafted plants had enormous root systems, maybe three times the size of my deep-planted normal plants growing alongside. Regarding the extra height needed to grow the grafted plants, I found I had to change my normal vine training technique anyway, because the grafted plants were much stronger/taller I trained them up and over the greenhouse roof, and ended up with more trusses.

        GROWING COMPARISONS:
        I grew grafted and non-grafted plants of the same variety side by side, both in the greenhouse and outdoors. In the greenhouse I grew some in the border soil (that had tomatoes grown in it from the previous year) and some in containers with good quality fresh multi-purpose compost.

        The biggest difference was noted in the greenhouse border soil, the grafted plants were both stronger and healthier and produced ripened fruit ahead of normal plants of the same varieties.

        In the greenhouse container grown plants there was little noticeable difference, the grafted plants ripened slightly earlier.

        For outdoor plants I never noticed any difference in growth between grafted and normal. This may have been down to the terrible weather in 2012 and also that Blight wiped out most of my outdoor plants early on.
         
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        • JWK

          JWK Gardener

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          WHAT I LEARNED:

          Varieties: ‘Gardeners Delight’ was by far the easiest variety to take being grafted. In contrast the bush (determinate) variety ‘Siberian’ just wilted and died at an early stage and the one plant that did survive only produced a measly handful of ripe fruit.
          Timings are critical to get the rootstock and scion to match up. On my small scale I need to stagger the sowing of rootstock over a period of time rather than all planned at once, this will allow for some variations in size & growth rates.


          AUBERGINE AS A ROOTSTOCK
          I’d read that Aubergines were used as a rootstock for tomatoes in the far-east. Given that a packet of Aubergines seed is very cheap it was worth experimenting. This did not turn out well, although the grafting was straight-forward the scion tomato rapidly outgrew Aubergine rootstock. Here you can see the difference in size of the rootsock and scion (when I made the graft they were identical diameters)

          IMG_6428 Tomato grafted onto Aubergine roots.JPG


          I ended up with stunted non-flowering plants. It’s an experiment I won’t be repeating
           
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          • JWK

            JWK Gardener

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            COSTS:
            The rootstock seeds are more expensive than normal seeds, 50 seeds cost £13 ish. Also there is a one-off expense of the grafting clips, these were about £8. Then there is the extra time involved in grafting, this was significant last year but I was learning then. Hopefully it will be easier/quicker this year and won’t take much longer than the normal chores of sowing, pricking out etc. Set against this is the saving of not having to replace the greenhouse border soil. For me that took a couple of hours at least, plus having to find some spare soil to replace it with that hadn’t had tomatoes/potatoes grown in it for 3 years was not straight-forward.

            CONCLUSION:
            Even though it is a bit fiddly and time consuming, for me tomato grafting is definitely worth doing for greenhouse border soil grown crops. It saves me having to replace the soil and the plants are much more vigorous. Choosing the right variety is important: Gardeners Delight has been great. Grafting is not worth doing for outdoor or container grown plants.
             
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            • JWK

              JWK Gardener

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              I'll be trying them again this year :)
               
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              • joolz68

                joolz68 Total Gardener

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                Looks like you put your heart& soul in there jwk :dbgrtmb: ive never heard of tom grafting,well done fella x
                 
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                • JWK

                  JWK Gardener

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                  Thanks Joolz. In a month or so the Garden Centres will start stocking them, apart from the big price difference they don't look that different to normal tomato plants, so easy to miss :blue thumb:
                   
                • joolz68

                  joolz68 Total Gardener

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                  I thought grafting was only done on wood stem plants jwk,im impressed :blue thumb: well done :) :) x
                   
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                  • Kristen

                    Kristen Under gardener

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                    :goodpost:Very impressive and informative post John, thanks for taking the trouble to write it.

                    You could "layer" them perhaps? Train them up a string wound on a "bobbin" of some sort, then unwind the bobbin and lower the plant. You need a "circuit" to arrange the plants around though, so its hard to do for a single row, for example. You should be able to get Tomato Hooks (I think they are called) to use for the Bobbins.

                    Last year my local Garden Centre over-stocked (or punters didn't want to pay the high price!!) and they were then sold off dirt-cheap - ideal for anyone who can wait a bit.

                    Any idea why the rootstock seed is so expensive? Market forces I suppose

                    Also wonder whether you have considered Aegis instead of Arnold for the rootstock? Cheaper, different pathogen resistance - not sure how you would decide which pathogens you need to protect again though :(

                    http://www.johnnyseeds.com/ have a number of rootstocks (couldn't get their filter system to work, but they have 5 or 6 varieties including Maxifort which seemed to be forerunner before Arnold etc., and some that are said to not increase vegetative vigour, but rather fruit vigour, which may be more suitable for an amateur greenhouse where a 60' long-season plant is not the objective!)

                    Found their video instructive too. Shows both side-grafting and then top-grafting. Side grafting looks better if there is a girth difference between rootstock and scion. He is then growing his plants to produce two leaders (either chopping it off just above cotyledons to get two equal shoots, with a cost of 10 days or so setback, or taking a sideshoot from just below the first truss [disadvantage for a commercial growing in having uneven shoots]). I've often thought about using double-cordon style to increase cropping. He was quite bullish about grafted Cucumbers and Aubergines too.

                    Are you rooting the tops you chop off the Rootstock for a later batch perhaps?
                     
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                    • Scrungee

                      Scrungee Well known for it

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                      I grow lots of tomatoes, but even I would have trouble making a minimum order:



                      Was that one of the national chains or a local independent GC?
                       
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                      • JWK

                        JWK Gardener

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                        Yes I had considered doing that, in the end I rigged up a support in the g.house roof si I could train them into the apex then down the other side. I thought the plants would object to growing downwards, but they didn't seem to mind.

                        I guess that not many people buy rootstock seeds in small quantities, maybe that's why they are so expensive?

                        It's very difficult to choose which rootstock, I can't recall why I picked Arnold but it does look to have a bigger list of pathogen protection. I've got some left over from last year so I'll use these up first.
                         
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                        • JWK

                          JWK Gardener

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                          Thanks, I recall looking at their website and their video was useful (although I failed successfully get that splice being demonstrated to actually 'take', it was far too fiddly and I think I was bruising the stems over-handling them). I think as Scrungee pointed out their shipping costs put me off using them.

                          Yes I tried that and as you can imagine they rooted very quickly and I enough for another grafting batch. It would be possible to save seed costs by starting say just two from seed very early (Jan say), then chopping up the seedlings to root a couple of dozen plants. The downside would be getting the timings right, as I found out the stems sizes really have to match the scions to get a reliable grafting joint.
                           
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                          • JWK

                            JWK Gardener

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                            It was a local independant one. I couldn't find any on ebay although Amazon were selling them from Holland I recall.
                             
                          • Scrungee

                            Scrungee Well known for it

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                            I couldn't find any at Amazon.co.uk, so googled 'tomato grafting clips Netherlands' and look what I got http://www.johnnyseeds.com/p-6972-silicone-grafting-clip.aspx Grrrrrrr!

                             
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                            • Freddy

                              Freddy Miserable git, well known for it

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                              Brilliant post John!:dbgrtmb: I wont be bothering with it, as I'm not so good at those fiddly jobs, and would only get down-hearted when it failed. Some very interesting points though:)
                               
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                              • Kristen

                                Kristen Under gardener

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                                The video on JohnnySeeds of their side-grafting technique made it look like some diameter difference would be tolerable whereas for a top-graft it looked like they had to be identical. The chap made it look disarmingly easy, and said he could do about 80 an hour ... rather him than me!

                                For the top graft (about 2/3rd the way through the video) he slipped [what looked to be] a collar onto the rootstock and then stuffed the Scion into the collar. I expect he aligned them so that the diagonally cut surfaces mated, but the speed he went at didn't make that obvious, but I was left wondering how those collars came off subsequently - they didn't look to be spring-loaded like the clips.
                                 
                              • Dave W

                                Dave W Total Gardener

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                                Many thanks John for passing on your experiences.:ThankYou: It was fascinating reading.
                                Seems like a lot of work. I wonder if that's where the term "hard graft" came from!
                                 
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                                • JWK

                                  JWK Gardener

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                                  Yes he does make it look easy and so fast :) For me I would have liked to have had a a practical lesson with seomone face to face rather than watvhing youtube videos.

                                  I tried a similar side-splice, like this one (photo taken just before I put the clip on):

                                  IMG_5956.JPG

                                  None of this sort of splice worked for me, the tension of the two seedlings seemed to spring them apart. Although the guy on the link was working slightly differently, using seedlings from seperate pots.
                                   
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                                  • JWK

                                    JWK Gardener

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                                    I think these are exactly the same silicon tube clips I ended up using, they are very flexible and have a slit so it's really easy to slip off. I think they are designed so that as the stem increases in diameter it pushes the tube off by itself:

                                    [​IMG]
                                     
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