In fruit tree catalogs, I've seen multi-grafted or multi-budded trees. Here's an example.
And I've also heard of a technique where you plant 3 or more trees in the same hole. Here's a youtube video talking about it.
Which one is better? Or what are the advantages and disadvantages of each technique? Is one likely to yield more fruit than the other?
What about planting multiple multi-grafted tree in one hole? I suspect that would be a bad idea, but I thought I'd bring up the possibility.
The question is where you want the competition for resources to take place. On multi grafted trees some of the grafts may grow faster due to their position or vigour. I have seen trees like this where one of the grafts fails but you are still getting fruit from the others. By planting three trees in one hole you are putting the competition for nutrients and water at the root level. If one fails you still have the others.
These are solutions for gardeners with limited space who have the time and interest to work with trees that are higher maintenance.
Edit: The advantages of multi graft or multi stem apple trees is that the different types can pollinate each other. If you only have room for one tree or one clump and there are no other apple trees around this is real advantage.
Both types of grafted trees require more skill and time to prune. You have to ensure that all parts are getting enough light. A clump of different apple types could get a bit tricky to prune but nothing out of the ordinary. I don't think the yield of fruit or quality will be any different between the two types so it comes down to space available and price.
