Pretty sure I know the answer, But.........

[Stanhoney]

Recently moved into new house, Loveley garden but gone to seed a bit. there are two Magnolia trees in the corner, look nice but if I were here twenty years ago I would have opted for Apple trees.

What are the chances of success of planting two Apple trees next to the Magnolias and as they grow cut back and eventually get rid of the Magnolias as the Apples take over. It would be nice to keep the coverage and not have an open space until the Apples are well established.

Don't worry about calling it a silly idea, I think it is aswell but 'I Know nothing' as they say

[David Hare-Scott]

It depends on what you mean by "next to". The closer they are the more the existing trees take sun, water and nutrients from the apples and the less chance the apples have of establishing and growing well. As the magnolias already have established canopies and root systems they are way in front. You can reduce the canopy but not the root system unless you kill the magnolia. You could end up with none doing well and you have ruined two good trees for no benefit.

David