Justin Valliere, Assistant Professor of Cooperative Extension, Invasive Weed & Restoration Ecology, UC Davis
Rachael Long, Emeritus Farm Advisor for Field Crops, Pest Management

Field edges are a common source of weed intrusion into farms, often requiring intensive management. Establishing hedgerows of native California perennial plant species offers a proactive approach for reducing weed invasion while lowering the need for herbicide use and non-chemical control. Our recent research1 in California found that orchard and crop borders planted with native perennials had significantly fewer weedy plant species, with lower overall cover and diversity of weeds. Although some growers may be concerned that hedgerows could introduce or harbor weeds, our findings demonstrate the opposite effect – native plantings can instead serve as an effective barrier against weed invasion.

We compared weed abundance, cover, and diversity in native hedgerows and conventionally managed field edges across 20 farm sites in California’s Central Valley, spanning orchards (walnuts and almonds), row crops, and field crops. Native hedgerows significantly reduced weed abundance and diversity along field borders, and at some sites, these benefits extended into adjacent crops, where we observed lower weed cover and fewer weed species. These benefits were especially apparent in the orchards included in the study. Orchard borders with hedgerows had significantly lower weed density, cover (Figure 1), and diversity. These benefits also extended far into orchards, with lower weed abundance observed up to 10 meters into tree rows and avenues.

These reductions in weeds with established native hedgerows also led to lower weed management costs for growers, decreased herbicide use, and reduced investment in control efforts on field borders. This study highlights how planting such native hedgerows can save time, money, and resources invested in weed control.

Figure 1. Weed numbers in orchards at field borders, edges, and within crop rows and avenues in those with conventionally managed field borders and those planted with native hedgerows.

Multiple benefits of native hedgerows
This study adds to a growing body of evidence demonstrating the benefits of native hedgerows in farming systems, including:

• Enhancing biodiversity
• Expanding wildlife habitat
• Improving erosion control
• Increasing soil carbon sequestration
• Supporting natural enemies for pest control
• Boosting pollinator populations
• Improving weed management and reducing control costs
• Lowering herbicide use

Important considerations
Installing native hedgerows offers significant ecological and economic benefits. However, careful planning is essential:

• Select and establish native plants carefully to ensure successful growth
• Manage weeds diligently during early establishment to support plant survival
• Take advantage of available grants and incentives to offset installation costs
• Consider hedgerow design and placement to maintain equipment access and operational efficiency

You can learn more about designing and installing native hedgerows on farms here.

Figure 2. Example of an established native hedgerow along a field border (Photo credit: Rachael Long)

1Long RF, Valliere JM. Established native hedgerows on field borders suppress weeds on farms. Weed Science. Published online 2025:1-20. doi:10.1017/wsc.2025.2