Companion planting is a horticultural method that involves strategically placing different plant species near one another to achieve a mutual benefit in the garden. In viticulture and home grape growing, this practice uses neighboring plants to enhance vine health, manage pests, and improve the quality of the soil ecosystem. This approach reduces reliance on synthetic interventions by fostering a balanced environment around the grapevines. By understanding which plants offer support and which present a risk, growers can create a thriving, productive vineyard environment.
Plants That Support Grapevine Vigor and Health
The strategic placement of certain plants can provide specialized benefits to grapevines, often categorized by their primary function in the vineyard ecosystem. Some companion plants function as biological pest controls, deterring harmful insects with their aromatic compounds or attracting beneficial predatory species. Herbs like garlic, chives, and basil repel common pests such as spider mites and aphids due to their strong, pungent odors. Geraniums are also useful for their ability to deter leafhoppers and Japanese beetles, two insects known to cause significant damage to grapevine foliage.
Other plants improve the soil structure and fertility that grapevines rely upon for sustained growth. Legumes, including vetch, clover, and peas, fix atmospheric nitrogen into the soil through a symbiotic relationship with bacteria in their root nodules. This process provides a slow-release source of nitrogen, a nutrient necessary for healthy shoot and leaf development. Deep-rooted companions, such as asparagus or yarrow, help to break up compacted soil layers, which improves aeration and allows for better water infiltration around the grapevine’s root zone.
A third category focuses on bolstering the population of predatory and parasitic insects that naturally control grapevine pests. Flowering plants like yarrow and sweet alyssum have delicate, easily accessible flowers that attract beneficial insects such as lacewings and hoverflies, which prey on aphids and other soft-bodied pests. Lavender is another popular choice, not only for attracting pollinators but also for its drought tolerance, which matches the preference of grapevines for well-drained soil conditions. Nasturtiums can be used as a trap crop, drawing aphids away from the vines, while chamomile is often cited for its potential to help suppress mildew, a common fungal disease.
Plants to Avoid Due to Competition or Disease Risk
While many plants offer symbiotic benefits, others can actively harm grapevines through aggressive competition for resources or by acting as reservoirs for diseases. Large, fast-growing vegetables, like cabbage and other Brassicas, are heavy feeders that consume substantial amounts of water and nutrients. Their proximity to shallow-rooted grapevines can lead to direct competition, effectively starving the vine of necessary moisture and fertility.
Vigorous cane and bramble fruits, such as raspberries and blackberries, must be avoided due to their expansive and aggressive root systems. These plants compete intensely with grapevines for water and soil nutrients, potentially stunting the growth and reducing the yield of the grapes. Similarly, perennial plants with spreading root structures can rapidly take over the space needed by the grapevines, increasing the need for constant maintenance and root pruning.
Allelopathic plants release biochemicals from their roots or decaying foliage that inhibit the growth of surrounding species. The black walnut tree is a prime example, producing a compound called juglone that is toxic to grapevines and can cause stunting or death. Fennel is another strong allelopathic plant that should be kept far away from grapevines, as its secretions can negatively affect the vine’s development.
Plants that host common grapevine diseases also pose a risk and should be avoided. Roses, for instance, are sometimes planted as an “early warning system” for fungal issues like powdery mildew, but they can also serve as a host for the disease, potentially transferring it to the grapevines. Planting known disease hosts in close proximity to the vines increases the overall pathogen load in the immediate area.
Best Practices for Integrating Companion Plants
Successful companion planting requires careful consideration of placement and ongoing maintenance to ensure the vines remain the priority crop. The most important practice is maintaining an adequate buffer zone around the base of each grapevine. A clear area of two to three feet should be kept free of companion plants to eliminate direct root competition for water and nutrients, especially during the vine’s establishment phase.
Companion plants should be low-growing to prevent them from shading the grapevine’s lower leaves, which need sunlight for photosynthesis and fruit ripening. If using taller beneficial plants like sunflowers, position them strategically on the side that provides only temporary, filtered shade during the hottest part of the day.
The scale of planting dictates the appropriate integration strategy. For a small backyard trellis, companion plants can be interplanted in small clusters or containers. For larger row-based plantings, cover crops like clover or vetch are sown between the rows and mowed periodically to prevent them from becoming overly competitive. Mowing helps manage their vigor while still allowing them to deposit nitrogen and improve soil structure.
Companion plants must be managed to prevent them from becoming pests, particularly those with aggressive spreading habits like mint. Planting such species in buried containers confines their root systems and prevents encroachment on the grapevine’s root zone. Regular pruning and harvesting ensures they remain a benefit rather than a source of competition or excessive foliage that restricts air circulation.