Often when visiting people's yards, the owner will tell me how poor the soil was initially and how much work was required to develop it. Soil amending is backbreaking and expensive. Today, I want to talk about a technique for maximizing tree growth in poor soil. The technique is called Colonization.
Trees grown in forests live longer, are more disease and pest resistant, and are more drought tolerant than trees in our landscapes. For maximum tree health, we need to mimic what the forest does. In a nutshell, forests drop large amounts of organic matter every year onto the soil surface to slowly decompose.
Ideally, you would begin the year before planting by depositing at least 4 inches of ground up tree trimmings. (Make friends with the people who clear the power lines and chip the trimmings.) Then keep it moist. The bigger your mulch circle the better, up to 6 feet in diameter. If you don't have the year to wait, go ahead and proceed from this point.
When planting the tree, we introduce an organism that has proven extremely beneficial, mycorihizal fungi. Mycorihizal fungi can be found at most quality garden centers. It can be purchased as a powder or in liquid form. When planting, we pull back the mulch before digging. Dig a hole no deeper than the root ball of the tree. (I actually dig them slightly more shallow.) Remember the old nurseryman's rule. Plant too low, it won't grow! Plant too high, it won't die! Mix fungi with the back-fill dirt, saving some fungi to apply to the surface. When you have finished back-filling and applying your surface fungi, re-mulch. You should keep the mulch at least 2 to 3 inches from the tree trunk.
The fungi forms a symbiotic relationship with the tree, providing nutrients in a form that the tree can use.
Reapply mulch as it decomposes. it's really that simple!