Dig the Hole First

Before you unpot your plant, prepare a hole fifty to a hundred percent larger than the plant's root ball. Work some compost, peat moss or other soil conditioners into the soil you've removed. When planting smaller perennials or bedding plants, rather than preparing individual holes, it may be simpler to amend a larger area and use a trowel to place the individual plants.

In the case of large trees, it is generally best not to amend the soil too much. The roots of the tree will try fairly quickly to spread past the prepared area, and if the composition of this soil is significantly different from that of the surrounding area, the roots can have trouble getting past the barrier. If the tree is going to have to survive in a primarily clay soil, you won't be doing it any favors by creating a super-rich loam immediately around the root ball.