Weed Management in Commercially Grown Sunflowers as Cut Flowers

Commodities

• Agronomic: sunflower

Practices

• Pest Management: chemical control, mulching - vegetative, soil solarization

Season after season, cut flower farmers find themselves losing income due to invasive weeds overtaking and hindering the productivity of their crops. What’s more, there is limited data pertaining to weed control options and their efficacy for farmers and their crops. This study aims to address this issue by evaluating five weed control methods (WCM) in the cut flower production of sunflowers. The methods to be evaluated include two conventional herbicides (Trifluralin and Sulfentrazone), two locally-sourced and natural mulches (straw and wool), and one manual technique (hand weeding), with all of these in combination with solarization. The study will evaluate each of these methods over the course of two growing seasons, 2025 and 2026, each with twelve replications per season. Data will be collected by evaluating the number of marketable stems, variety and frequency of weed survival, best WCM based on cost of production per stem or unit area, and market feedback. Research dissemination will take place via Utah State University Extension fact sheets, a Zoom webinar, an on-site tour and field day, and a national grower magazine article. Unique to this study, a high school student researcher will be collaborating and presenting results at a local level, with potential of competing with the project on a regional, state, and national level.

Research Objectives

Objective 1:  Test and identify which Weed Control Method (WCM) results in the largest percentage of marketable annual sunflowers (Helianthus annus) for cut flower production by end of growing seasons in 2025 and 2026. WCM will be evaluated to represent conventional and natural methods for flower farming.

Objective 2:  Test and identify which weeds are most successfully controlled and which are persisting by WCM by the end of the growing season in 2026.

Objective 3: Identify which of the weed control methods in the cut flower production of sunflowers is the most profitable.

Educational Objectives

Utilize Roo Crew Farms’ social media (Instagram and Facebook) to post a minimum of three posts related to project implementation, research findings, and educational aspects of this project annually.

Publish one, USU Extension Fact Sheet on best practices of cultivating sunflowers as a cut flower crop in Utah (January 2026).

Publish one, USU Extension Fact Sheet on weed management in cut flower production of sunflowers in Utah for other cut flower growers in Utah (January 2027).

Host one field day at Roo Crew Farms showcasing the study and 1.5 years of data collection (Fall 2026).

Present one Blooming Zoom webinar for Utah Cut Flower Farmer Association (late 2026).

Publish an article in Growing For Market Magazine focusing on research findings

Work with High School students to present findings at the local FFA chapter Science Fair Contest with the potential of presenting at a state or possibly even at the national level.