- Malheur Experiment Station
In commercial wildflower production, weeds (any unwanted vegetation) compete with wildflowers for light, nutrients, and water, and can consequently prevent wildflower establishment (Gallitano, Skroch, & Bailey, 1993). While there are many options for weed prevention, herbicide use and certain fumigation methods are not always among them, since most products are not labeled for wildflower seed production. However, there are alternatives that effectively control weeds. Currently, weed control for wildflower seed production is through cultivation and hand-weeding. Weed control can be aided by subsurface drip irrigation, weed-suppressing barriers (such as composted mulch, plastic film, or landscaping fabric paper) and a soil solarization aid (Grattan, Schwankl, & Lannini, 1988).
Because many herbicides for wildflower production have yet to be labeled, forb growers could use sub-surface drip irrigation to help manage weeds. Weed seed germination is related to the water content of the surface soil, and consequently both sprinkler and furrow irrigation have proven to produce considerable amounts of weeds on the bed and in the corrugate (Grattan, Schwankl, & Lanini, 1988). Sub-surface irrigation can be managed to bring less water to the first inch of the soil surface and allow forbs to flower without stimulating as much weed growth. Other practices, such as the use of mulches and soil solarization, have also demonstrated strong weed-controlling capabilities. Mulches are barriers that prevent light and water from reaching weed seeds, thwarting weed germination. Material possibilities for mulches include compost, gravel, and landscaping fabric (Mulches). Soil solarization is the practice of laying plasting sheeting over the top of a field before planting a given crop (Stapleton, 2008). The plastic sheet captures heat from the sun in the soil, increasing the temperature of the soil to kill weeds, fungi, bacteria, and nematodes (Stapleton, 2008). Soil solarization is most effective when the weather is hottest (Stapleton, 2008).