By Ayanava Majumdar, Olivia Fuller and David Lawrence
Small farms are diversified farms that grow many crops in a limited space. One question that is asked very commonly is whether it is advisable to interplant ornamentals with vegetable crops, also known as companion planting. It is somewhat common to see ornamental plants in rows with vegetables, for example, in high tunnels or raised beds where space is limited.
This article looks at the pros and cons of companion planting. Ultimately, producers will make the decision on interplanting based on their experience, since there is a lot of unknown ecological variables at play here.
There are many advantages to growing ornamentals with vegetables.
The pollinators that ornamental plants attract can tremendously benefit insect-pollinated vegetable crops grown nearby. Besides pollinators, ornamental plants can also attract beneficial insects of various types, for example, lady beetles. So, the flower patch can serve as a pollinator and beneficial insect habitat.
A big advantage of the ornamental-vegetable mix is aesthetics. This can be a major advantage for urban farms and curated gardens where there is direct interaction with consumers.
Rapid ground cover with bushy ornamentals can smother weeds when planted on field edges. Some information is also available on the nematode-killing power of ornamental plants and herbs that mask the smell of main crops, which deters insect pests. Growers must pay attention to their ornamental plants, canopy structure and planting orientation relative to other vegetable crops for optimizing these benefits.
Now let’s examine some of the disadvantages.
Trap-crop research (trap crops lure away insect pests from main crops) has shown that certain ornamental plants like sunflowers can lure in stink bugs, leaffooted bugs and other pests from a distance due to their height. Those sucking pests may eventually move to vegetable crops.
Certain invasive pests may also establish themselves on ornamentals, eventually becoming quite common in the ecosystem. Think about the western flower thrips and how widespread of a problem they are in many row and horticultural crops. Spider mites, like the two-spotted spider mite, are also a very big problem in ornamental plants and shrubs. These pests can jump to vegetable crops where they can be very difficult and expensive to control. Close proximity of ornamental plants with horticultural crops can be very problematic for organic farmers where control choices are limited.
Ways to reduce the spread of pests include having additional space between the ornamentals and vegetables, limiting movement between rows and regularly monitoring any hot spots for spot-treatments if needed. Carefully plan your crop rotation, cultivars and plant spacing to avoid pest buildup and hot spots of insect activity. Consult the Extension office in your state for the latest recommendations.
Always test low-cost alternative pest prevention methods like sanitation, pest exclusion systems and others before making harsh treatment decisions. Long-term IPM strategies with good record-keeping can be more useful than short-term solutions that are environmentally harmful.
Specialty crop growers should scout weekly or more often. To stay current with integrated pest management (IPM) research and pest alerts in Alabama, subscribe to the Alabama IPM Communicator E-newsletter (www.aces.edu/ipmcommunicator). Use the Farming Basics mobile app to subscribe to the newsletter, identify common insects/diseases/weeds, connect to beginning farmer resources and to contact a commercial horticulture regional Extension agent in Alabama.
Ayanava Majumdar is an Extension professor and entomologist at Auburn University. Chip East and Eric Schavey are regional Extension agents with the Alabama Cooperative Extension System.