Hedgerow plantings of native flowering plants adjacent to tree nut orchards is not a common practice in California, but studies have shown these habitat plantings can have positive impacts on orchard diversity, especially for bee pollinators.

Hedgerows are not just densely planted trees; native perennial grasses, shrubs and even small forb plants like milkweed can serve as hedgerows, allowing for adaptability in different farming situations. Hedgerow habitat plantings on field edges have been known to provide habitat for pollinators and other beneficial insects, and due to recent studies, they are now being recognized as a valuable component in a weed control program.

Rachael Long, UCCE farm advisor emeritus in Yolo County, along with Dr. Justin Valliere from the UC Davis Department of Plant Sciences, have published new information on hedgerow plantings that focuses on their role in weed control.

Regardless of the reason for hedgerow plantings, site selection and preparation, choosing appropriate plants and spacing and providing irrigation to get the plants established are the first steps in a field edge habitat planting program.

Pollinator Value

Recognizing hedgerow value in the almond industry for attracting bee pollinators, the Almond Alliance has stepped up to provide grants for hedgerow establishment along almond orchards in partnership with the Great Valley Seed Company of Los Banos. Nicole Gault of Almond Alliance said since November 2023, 17,840 linear feet of hedgerows have been planted. This fall, another 11,400 feet of hedgerows will be planted.

Long said the easiest hedgerow planting to manage is a single row of flowering shrubs and perennial forbs like yarrow along an orchard edge, keeping in mind placement for access to the orchard.

Hedgerow plantings can be easier to establish and maintain in parts of California that receive more rainfall, but with careful planning, native plants can survive and thrive in more arid areas. Mandeep Riar, UCCE restoration ecologist and weed science area advisor in Kern, Tulare and Kings counties, said hedgerows can be valuable additions to orchards once they are established. Innovative growers in her part of the San Joaquin Valley are seeing success with hedgerow plantings, she said. Appropriate plants for hedgerows need to be selected and the site will need to be irrigated for about the first three years after planting, but she notes the return on investment can be significant in terms of increased bees and natural enemies on farms for pollination and pest control services and weed suppression.

“Once their root systems are established, they don’t need intensive management,” Riar said.

Growers are realizing the benefits of hedgerows in their orchard systems and are planting them, she confirmed. Most are mixtures of native flowering plants, such as coyote brush. Milkweed is also popular for providing nutrition for Monarch butterflies and other insects species that feed on nectar.

Nectar Supply

Frank Olagaray, who farms almond, walnuts, olives and winegrapes in the Thornton area, said he planted his first hedgerow along his orchards in 2019 with the idea of providing a food supply for native pollinators. His five miles of hedgerows are native shrubs in the 2- to 6-foot height range, though he said they would get taller if he did not cut them back. Weed control was not a driving force in the decision to plant hedgerows, he said. His plants were chosen to supply wild pollinators with blooms and nectar year-round. The benefit provided for him, he said, is the abundance of predator insects the hedgerows attract, which disperse into adjacent crops, keeping down mite populations in his nut orchards.

The Xerces Society for invertebrate conservation can help growers with plant selection. Their website lists specific plants for California’s Central Valley, noting which attract beneficial insects and their bloom times, and the preferred soils. These native species include yarrow, milkweed, coyotebrush, California lilac, Western redbud, toyon and coffeeberry. Xerces Society recommends selecting at least three different plant species from early, mid and late blooming periods.

Species vary in their water needs, but Olagaray said he prefers to continue irrigating when plants are mature so they will produce more nectar for beneficial insects.

The cooler weather in the Delta area likely contributes to the good growth of the hedgerow plants, Olagary said, but he still has to contend with voles and gophers chewing on irrigation lines.

Due to hedgerow plant ability to store carbon in their woody plant tissue and in their soil root zone, planting hedgerows is an eligible practice for CDFA’s Healthy Soils program that pays per linear foot for hedgerow plantings.

Olagaray said the first step in hedgerow establishment was to pull up berms for the hedgerow plantings along the orchard edges. The berms are 1 foot high and 3 feet wide. He then lays a drip hose with emitters installed every 3 feet. Over the drip line, he places a layer of mulch. When he is ready to plant, he turns on the water to see where the emitters are, pulls mulch aside and plants the plugs (a smaller, more economically sized plant) in the wetted areas.

Weed Reduction

In Long and Valliere’s study on 20 field sites, hedgerows of native California plants established on orchard borders helped suppress weed abundance and diversity on field edges by shading out and competing with weeds for moisture and sunlight. This weed reduction included troublesome and difficult-to-control weeds in both orchards and field crops.

In addition, the study found the weed suppression resulted in reduced weed drift distant into adjacent orchards compared with open field edges where more weeds tend to persist. Overall, Long said hedgerow plantings showed reduced herbicide use and costs of managing weeds compared with clean field borders.

Establishment costs vary on location. The costs, besides plants or seed mixes, include labor for site analysis, design and field preparation. Long noted maintenance costs will decline as the native perennial grasses or shrubs mature and outcompete weeds.

Gault said almond growers or growers of other commodities who want to learn more about hedgerow planting and funding can go to pollinatoralliance.farm. After uploading information about their planned site or sites, a restoration biologist will determine the best-suited plants for their location. Growers can also choose appropriate plants. Growers can receive $5.43 per linear foot of hedgerow planted. Establishment of a hedgerow planting earns the grower a “Bee Friendly” certification. The grant funding comes with a three-year commitment to maintain the hedgerows and send photo proof of hedgerow plantings every three months to Almond Alliance.