Where to plant apple trees
If planting directly into the garden, the RHS recommended against planting a hole too deep for the tree to sit in.Instead, dig to the exact same depth as the roots, with a diameter three times that of the root system.To ideal this measurement, the RHS advised spreading the roots out on the ground before digging the hole.It said: “If the sides or base of the planting hole are actually difficult, break the soil up with a fork prior to planting.”
Source: https://www.express.co.uk/life-style/garden/1685265/when-to-plant-apple-trees-autumn-frost-bare-root