Weeds compete with desirable plants for water and nutrients. In most cases they compete very well. Due to their location on the soil surface, they get first crack at water and nutrients. If that weren’t enough, most of us, and more importantly your customers, consider them to be downright ugly. Unless you’re working for a fan of scruffy, gnarly water and nutrient robbers, they’ve got to go. Fortunately, there are several good options in the endeavor of controlling weed growth under or near trees and shrubs:
Mulch: Application of mulch is a good step in the replication of a natural landscape. Begin by applying 2 to 3 inches of wood chips or stump grindings starting 3 inches away from the tree trunk root flare. These materials facilitate the movement of water and air through the profile.
Ground covers and perennials: If the customer insists on something other than mulch, a good option is a ground cover/perennial mix. The basic idea is to shoehorn in shade-adapted ground covers and perennials in between the flare roots. Perennials or ground covers under trees is a better choice than annuals in that annuals are planted yearly, so the risk of damaging tree roots is increased.
Preemergence herbicides: This group of herbicides is widely used on lawns and landscape beds to prevent the growth of annual weeds such as crabgrass, pigweed and yellow nutsedge. They generally have limited root activity and are considered fairly safe around most woody plant species.
Soil inactive herbicides: These are often the nonselective, systemic varieties. Care must be taken to avoid herbicide contact with the tree trunk or any green tissues, including suckers.
Physical removal: Especially during conversion from turf to a healthy soil covering, physical removal of existing weeds is an important procedure. Usually reserved for new hires, this step often needs to be repeated several times in order to achieve the objective, especially when trees such as mulberry and Siberian elm are growing near the trunk of a desirable tree.
Read more: Controlling Weeds Near Trees