Soil that contains a lot of clay is far from ideal when it comes to planting trees. Clay can be a problem for gardeners, landscapers and homeowners all over the country, but there are a variety of trees that can grow well in clay soils. There are also measures you can take to give your new trees the best chance of surviving.
Problems With Clay Soil
Clay soils tend to have poor drainage, meaning that water does not pass through them easily. This can be a problem for trees, because standing water can suffocate a tree's roots. Clay soil is also dense and compacts easily, making if difficult for the roots of a young tree to grow. In many cases, clay soil is also low in nutrients.
Rather than digging a hole large enough to accommodate the entire root ball of your young tree, till the soil and dig a shallow, saucer-shaped hole about half the depth of the tree's roots. Set the tree in the hole and cover over the root ball with a mixture of 2/3 native soil and 1/3 organic matter. Additional amendments and fertilisers will depend on your specific conditions. A soil test will tell you the pH and nutrient content of your soil.
Deciduous trees are trees that shed their leaves in autumn and regrow them the following spring. A number of deciduous trees are well-suited to growing in clay soil. Silver maple, river birch, bur oak and shag-bark hickory are all good trees for clay, as are black ash, butternut, crab apple and elm.
Conifers are evergreen trees that have needle-like leaves that stay green year-round. Fir trees like white fir and balsam fir are adapted to clay soil, along with spruce varieties like Norway spruce and Black Hills spruce. If you are looking for pine trees for clay soil, try Austrian pine, white pine, Scots pine or ponderosa pine.