If you are planting your Apple tree in open ground (as opposed to training against a wall or fence) it is possible the tree will need supporting. In most cases it is the rootstock which determines what is required – some trees will need support for their entire lives, and will therefore require a permanent stake or post, whereas some will need a temporary post or stake for a few years to help them get established.
If your Apple tree needs a permanent stake, this should be planted before the tree if possible, because banging in a permanent tree stake requires a large hammer – and you don’t want to accidentally hit your new tree.
Permanent tree stakes are usually wooden posts 6ft – 8ft / 2m – 2.5m tall by about 2″ – 3″ / 5-7cm, sharpened at one end and treated with preservative. Metal stakes (e.g. used for grape vines) are also suitable. In either case the best way to plant the stake is to start a pilot hole using a crowbar, then lift the post and force it bodily down into the pilot hole as far as it will go. Then use a hammer to bang the stake firmly into the ground.
If you are using a wooden stake you can prevent the top of the stake from splintering under the hammer by putting a metal jam jar lid over the top first. The stake will probably need to go in 2ft / 40cm-50cm or more depending on the type of soil – but it is easy to tell when it has gone far enough, because it will be firmly in the ground but still with a bit of give. Check the alignment as you bang it progressively further into the ground.
If your tree needs a temporary stake, you can go ahead and plant the tree first.