Can I use a very young tree?

I was just wondering whether I can use a very young tree to make a bonsai.Specifically I was thinking about olive tree.

The simple answer is yes. To make a good bonsai though, it would be better to grow the tree in the ground until it is the thickness you want. Olives grow very slowly in pots and much faster in the ground. Cut it back and dig it up when it has got the thickness of trunk that you'd like and then regrow new branches and style them.

Thank you Kev!I'll plant the olive tree on the ground late in the afternoon.

Also,in my garden I have a hedge and I've found a few tiny hedge plants some metres away of the hedge.Could I try to form it as a bonsai?If yes,should I put it in a pot or leave it on the ground?

Stef wrote:
Also,in my garden I have a hedge and I've found a few tiny hedge plants some metres away of the hedge. Could I try to form it as a bonsai? If yes,should I put it in a pot or leave it on the ground?

We are missing some important information. We need to know where you are and what kind of a hedge it is. My guess is that you are in southern Europe, but please be more specific.
Most hedge plants make good bonsai, but some are better than others. Are these tiny hedge plants seedlings or suckers? Generally, for bonsai purposes you might do better to dig up a mature plant out of the hedge and put a couple of the baby ones in its place. Whichever you use, plant it in a growing bed for a year or two before you put it in a pot.

It is often a better route to a good bonsai to take a larger plant and cut it down to size.

Seedlings and other young plants take many years to develop the "opld" look we want in a bonsai.

I live in Cyprus an island in the Mediterranean near Greece and Turkey.
Unfortunately I don't really know the exact type of the hedge.The little plant I've found is around 20 cm (height) and looks quite lush. I've heard that after hedges rise over the height we want them to be, we can cut the top of them so they won't grow up fastly.Could I use this technique with the little hedge after a while?