Trees and Turf

Updated: Sep 21

Tree and grass selection, competition among plants, maintenance

practices, and special situations must all be considered when trees and turf share a landscape.

Selection

When trees and turf are used in the same area, extra attention must be given to plant material selection to ensure tree and lawn compatibility. Grass is generally a sun-loving plant. Most species will not grow well in areas that get less than 50 percent open sunlight. However, new shade tolerant grass varieties are being introduced. In areas where the lawn is the primary design feature, select woody plants that are small, have open canopies (to allow sunlight to penetrate to the ground), or have a high canopy. Select trees that do not root near the soil surface. Surface rooting is most prevalent where shallow topsoil or clay soils are present.

Competition

All plants require sunlight, water, and rooting space for growth. In the landscape, plants compete with their neighbours for these resources. Some plants even release chemicals in the soil to restrict growth of nearby plants. A landscape design should provide adequate space for plants (keeping size at maturity in mind) to minimize competition.

While shading is the most obvious form of competition, roots also compete below ground for water, nutrients, and space. The majority of fine, water-absorbing tree and grass roots are in the top 6 inches (15 cm) of soil. In this region, grass roots ordinarily occupy a much greater percentage of the soil volume than tree roots and absorb more of the available water and nutrients (especially around young trees). However, grass root density is often much lower in areas where trees were established first. In these situations, shading and other factors help to make tree roots more competitive.

Competition is especially important when transplanting, seeding, or sodding. The newest plant in the area must be given special treatment to become established. Competing sod should be removed from around transplanted trees and shrubs. Water should be applied to new transplants and seedlings as needed.

Mulching is the best alternative to turf around trees. A 2- to 4-inch (5- to 10-cm) layer of wood chips, bark, or other organic material over the soil beneath the tree’s drip line is

recommended because it:

· helps retain soil moisture

· helps reduce weeds and grass competition

· increases soil biology and fertility as it decomposes

· improves appearance

· protects the trunk from serious injuries caused by lawn care equipment

· improves soil structure (better aeration,

temperature, and moisture conditions)

Maintenance Practices

Trees and turf have different requirements. Given the close proximity of tree and turf roots, treatment o