Weed Control in Landscape Plant Beds
Diminishing resources and client demands have made Sustainable Landscapes extremely important. Water-wise (or Xeriscape) native plant material, best management practices and water-efficient irrigation systems are crucial components of sustainability.
That being said, the one activity to which the most resources are allocated is vegetation management (i.e., weed control). A weed can be defined as either a plant growing where it is not wanted or a plant whose virtues are yet to be discovered. Weeds, be they grasses, wildflowers, vines, trees, shrubs or other categories of plant life, definitely keep a lot of people very busy. They can cause a plethora of problems, including eyesores in ornamental plantings, shading out vegetable gardens, posing wildfire threat to structures, releasing allergenic pollen into the air, and much more.
In ornamental landscape plantings, weeds are undesirable because they are deemed unattractive and compete with desirable plants for light, water, nutrients, C02 and space — often overtaking plantings, requiring complete renovation to solve the problem.
The sources of weeds in landscapes are many. They range from “seed banks” in nursery stock soils and top soil to those deposited in bird and wildlife droppings to underground food storage parts that existed before planting and weren’t controlled ahead of time. Weed propagules aren’t always seeds, but sometimes runners, rhizomes or even bulbs and bulb-like plant parts. A kid spitting a watermelon seed into the garden, hair from a dog brush containing burrs, wind currents, and debris from gutters are all sources of weeds.
The following are helpful tips for dealing with weeds in these situations. Some are more feasible than others. In professional/commercial landscape maintenance, labor is the biggest cost of performing work. Therefore, use of the most effective, efficient, industrious, labor-saving methods available is crucial to being productive, competitive and profitable. Manual removal of weeds by hand is not one of these methods, but there is a place for some of this.
Healthy plants with good root system will choke out potential weeds.
Purchase healthy nursery grown plants that do not have huge seed banks in the growing medium.
Install soils that are not particularly infested with problematic types of weed propagules,
Landscape fabrics, aka “weed barriers,” used on the soil surface are not perfect solutions, but help moderately.
Maintain a 3-inch mulch layer of a suitable product which does not contain weed seeds.
Mow adjacent lawn/turf grass areas with the discharge shoot pointing away from beds to avoid throwing seeds and plant parts into the beds.
Use low-volume irrigation, such as drip type, to water plant root systems but not favor weed development where there are no plants. Water only as necessary, as over-watering favors weed development.
Soil solarization provides weed control in warmer climates.
Spray non-selective, systemic herbicides on growing weeds away from plants, rather than pulling them. Pulling of weeds disturbs pre-emergent herbicide barriers and pulls weed seeds up with soil.
Gregg O’Connor is project manager – landscape for Charlotte County Public Works. He holds an A.A.S. in Ornamental Horticulture from S.U.N.Y. Alfred, and a B.S. in Vocational-Technical Education/Agricultural Subjects from S.U.N.Y. Oswego. He has formerly served as Cornell University extension agent – horticulture, Charlotte Technical Center instructor – horticulture, technical director for a pest management company, and grounds superintendent for an upscale retirement community.
