Two years ago I planted a 1.5 metre tuckeroo in a sunny location, which gets plenty of water. It is now 4 metres tall and very healthy looking with lots of new green foliage. Its fluffy, and named Kevin.

The tree was planted in a layer of topsoil (about 150mm) above a layer of clay soil about half a metre deep. Beneath the layer of clay is more porous soil.

Recently in a strong storm the tree ended up at a 45 degree angle to the ground. I pushed it straight and staked it, and there has been no obvious effect and the tree is still powering along putting out new growth.

I have noticed, however, that the tree does not seem firmly planted in the ground. It can be wobbled from side to side and it looks like the root ball is wobbling with it. It conjures up the image of a shoulder socket, with the ground being the socket and the tree being the arm bone and the root ball being the humerus.

I have little knowledge of trees but it appears to me that the tree has set down a long strong tap root but no lateral roots at all to stabalise it. I am assuming that the main water supply is from the porous layer beneath the clay layer so the tree id putting all its roots down there, leaving it unstable in the top 500 to 600 mm of clay soil.

Is there anything I can do to promote root growth or alleviate the situation?