Can Bush Beans Be Planted Next to Marigolds?

Similar Needs

• Marigolds and beans, like the warm-season crops, need warmer temperatures to perform well. Both require soil temperatures in excess of 60 degrees Fahrenheit. for germination. You can plant the seeds while the soil remains cooler, but the seeds will remain dormant until the temperature rises. Both crops can be planted late in the season, and doing so will help you avoid some issues with Mexican bean beetles.

Nematodes

• You should plant marigolds alongside beans for their suppressive effect on nematodes; according to the University of Florida Extension, marigolds help suppress 14 genera of nematodes that affect plants. Above-ground symptoms of root-knot nematodes (Meloidogyne spp.) in beans include stunted plants, midday wilt and pale leaves. Below ground, plants may show swellings on their roots called galls. The galls disrupt the vascular system of plants, leading to the above-ground symptoms. The Alabama Cooperative Extension System notes that nematodes are usually unevenly distributed, so you should not expect your full crop to be affected in to the same degree when nematodes are the cause. Other nematodes cause similar above-ground symptoms, but no galls on the roots.

Preventive Measures

• In addition to planting marigolds with beans, you can plant marigolds before and after bean cops to provide additional protection. Both African marigolds and French marigolds (Tagetes spp.) can serve as cover crops. These types of marigolds produce alpha-terthienyl, which reduces and suppresses nematodes in the soil. They should be planted at least two months before your bean crop to take advantage of the suppressive effects. Turn the plants into the soil to allow the plant material to continue to have a suppressive effect. According to the University of Florida Extension, you must match the type of marigold to the particular nematode issue affecting your garden, as some varieties work better than others against particular nematodes. A nematode assay of the soil can identify the nematodes present in your soil.

Other Benefits

• The flowers and foliage of French and African marigolds release compounds that have been demonstrated to kill and deter Mexican bean beetles. Additionally, the scent of marigolds may deter other insects from the garden. African and French marigolds have an allelopathic effect on the area where they're planted; the same chemical that suppresses nematodes allows the plants to reduces disease-causing organisms ranging from fungi to viruses. This in turn reduces the potential for disease development in beans.