Q: Please can you help. We planted a 5′ Robina Tree last week which has now sunk about 3″ below ground level.  Do we dig up and replant, or just top up with soil? Thanks Gill.

A: Ideally the base level of the original soil when it was in the pot should not be exceeded when planted in the ground.  If it is necessary to raise the level of the rootball of the tree, try not to lift the tree out completely but raise it by pushing soil underneath it with your foot by leaning the tree gently first one way and then the other.