Swiss chard is a hardy biennial typically grown as an annual in most vegetable gardens. Companion planting involves strategically placing different crops near each other to foster mutual growth and support within the garden ecosystem. This arrangement optimizes garden space, enhances plant health, and provides a natural defense against common pests and diseases, leading to a more productive crop.
Companion Plants That Provide Biological Benefits
Plants with strong aromatic qualities are effective companions for Swiss chard by confusing or deterring insect pests. Alliums, including onions, chives, and garlic, release sulfur compounds that mask the scent of chard leaves. This makes it difficult for damaging insects like aphids and flea beetles to locate the host plant, reducing pest pressure on young chard seedlings.
Certain herbs also offer protective advantages due to the volatile organic compounds they release. Mint, for example, is known to repel flea beetles, a common pest that chews holes in chard leaves. Planting aromatic herbs like rosemary and sage nearby can also help deter larger pests such as snails and slugs.
Annual flowers contribute to biological defense by attracting beneficial insects that prey on chard pests. Marigolds repel root-knot nematodes in the soil and can act as a trap crop for aphids, diverting them away from the chard foliage. Nasturtiums serve a similar function, luring aphids away while attracting helpful insects like parasitic wasps and hoverflies.
Maximizing Space With Complementary Root Systems
Companion planting maximizes the efficient use of garden space and soil resources by pairing plants with different growth structures and root depths. Swiss chard develops a moderately deep taproot, allowing it to access water and nutrients lower in the soil profile. This makes it an ideal companion for shallow-rooted, quick-maturing crops that utilize the topsoil layer.
Shallow-rooted vegetables like radishes and lettuce can be interplanted between chard plants without competing for resources. Radishes are harvested quickly, opening up space. Lettuce benefits from the partial shade provided by the taller chard leaves during the hottest parts of the day, ensuring both plants draw nutrients from different soil strata.
Legumes, such as bush beans and peas, function well as chard companions due to their distinct root systems. Bush beans do not shade the chard excessively or compete heavily for root space. Legumes also fix atmospheric nitrogen into the soil through a symbiotic relationship with Rhizobium bacteria, providing a slow-release nitrogen boost that benefits the chard’s leafy growth.
Plants That Inhibit Swiss Chard Growth
Some plants should be kept separate from Swiss chard to prevent competition or the spread of shared vulnerabilities. Plants in the Chenopodium family, including beets and spinach, are poor companions because they are susceptible to the same pests and diseases as chard. Planting these related vegetables together creates a dense concentration of vulnerable hosts, making it easier for pests like leaf miners to devastate the crop.
Members of the brassica family, such as kale, broccoli, and cabbage, should be planted with caution. They are heavy feeders that compete intensely with chard for nitrogen and other soil nutrients. Their strong demand for the same resources can stunt the growth of both the brassica and the chard, and shared susceptibility to pests like the cabbage worm further complicates this pairing.
Fennel is a notable inhibitor because it exhibits allelopathy, a phenomenon where a plant releases biochemicals that suppress the growth of nearby vegetation. Extracts from fennel leaves and seeds have been shown in laboratory studies to inhibit the germination and seedling growth of various plants. Although the exact effect on mature chard varies, the release of these growth-inhibiting compounds makes fennel an unreliable and generally discouraged neighbor for almost all garden vegetables.