One for the home education forest school group- and anyone else interested in fruit tree grafting!
15 M26 semi-dwarfing apple tree rootstocks arrived in late February for the forest school group to graft their own apple trees from community orchard heritage varieties (the heritage trees need pruning- this was going to be a 2-for-the-price-of-1 activity using prunings to graft new trees). Unfortunately, Covid-19 has meant we can't do the activity- but fortunately we have 4 good apple varieties in our garden, so hopefully if these grafts take all the forest school people can have a new tree in the autumn.
Fruit trees are usually grafted onto rootstocks. This means that a twig or bud from one tree is attached to roots from another tree. You can graft more than one variety of fruit onto one set of roots- "family trees" can have 4 or more varieties of a fruit on a single tree (they all have to be compatible with the rootstock, though- you can't have an apple peach tree, sadly, just lots of sorts of apple OR peach (or pear, plum...) on one tree with the right sort of roots).
The reason for grafting is that if you grow fruits from seed, you won't end up with the same variety of fruit you got the seed from. This is due to genetic recombination in sexual reproduction. To get the same variety of fruit, you need a clone. Grafting trees produces clones- every Cox apple is grown on a genetically identical tree to every other Cox apple.
Cuttings and layering also produce clones- but these grow on their own roots. We usually grow fruit trees on different roots from their own because fruit trees on their own roots will grow really big and take many years to fruit. Small trees are easier to pick fruit from, and waiting 10 years for any fruit at all takes a lot of patience. So rootstocks have been developed which kind of bonsai the tree, starving it slightly (or starving it a lot, for very dwarfing rootstocks), which makes the tree stay smaller and fruit more quickly (because it thinks it's struggling to grow and needs to produce seed quickly in case it dies). This sounds a bit mean- but the trees don't mind!
There are so many good videos of how to graft fruit trees on YouTube I'm not even going to do links. There are almost as many methods as there are videos (well, that's a slight exaggeration, but there are a whole lot of grafting methods), but they all have one thing in common:
The growing layer of the tree, called the cambium, lies just under the bark. The cambium layer of the rootstock tree and the cambium layer of the new tree have to match up so that the roots can feed the new grafted bud or twig. All grafting methods are designed to make this happen. I chose to use one straightforward method as I thought it was the most suitable for the rootstocks we had and, if it works, is a good method for the forest school group to use next year.
As you can see, all you need for grafting is a sharp knife (if you don't know how to sharpen knives, that's a great thing to investigate- sharp knives are much safer than blunt knives as they don't slip- and also they're a lot more use), some plants you want to graft, and some tape, raffia or clingfilm. If you don't have rootstocks but do have access to at least one fruit tree and can get to an orchard or swop sticks with a neighbour, you could have a go at making your very own family fruit trees too: I'm definitely going to be bud grafting some interesting varieties onto my trees once the lockdown has finished!