(By Gina Gervase, Communications Assistant)
The air is crisp, the trees ignite in buoyant shades of yellow, and the evenings suddenly seem longer. It is fall in the Pacific Northwest. Our gardens have started to slow but some vegetables are just making their entrance. In a field of green, bright pops of orange are found underfoot. Squash, one of the Three Sisters, is ready to harvest.
Though squash gets all of the attention this time of year as her two sisters, corn and bean, have already wound down, the sisters work better together than apart.
Planting of the Three Sisters together – beans, corn and squash – spread across Mesoamerica at least 5,000 years ago. The combination, which provides a supportive environment for growth together, also provides complete protein when consumed together. The Three Sisters form the basis of Native American diet along with meats from rabbit, deer and buffalo.
Corn, the oldest sister, grows up tall and lanky. She provides support for her younger sister, bean, to grow up her stalks into the sunshine. While bean receives support from corn, she also gives back by pulling nitrogen from the air and depositing it into the soil. Legumes, which includes peas and beans, are nitrogen-fixing plants. They have the ability to pull atmospheric nitrogen from the air and convert it into ammonium nitrogen that other non-nitrogen fixing plants can draw in through their roots. Nitrogen is one of the essential elements of plant growth yet most plants can only draw in nitrogen from the soil. Maize and squash take it in hungrily, spurring growth. As squash begins to grow next to her sisters, she acts as a living mulch, shading the soils to keep it cool (especially for corn’s shallow roots), moist and free of weeds while also providing prickly protection from hungry critters.
Though the idea is old, it is an example of a farming technique still used today, companion planting. The theory is that some types of plants benefit from being around other plants rather than being planted solely among their own kind. Companion planting is an effective alternative to pesticides, used to deter insects, prevent disease, encourage beneficial bugs, provide nutrients and control weeds.
Besides the Three Sisters, French marigolds are used in companion planting as they secrete a chemical that kills nematodes. Marigolds can be helpful to plant as a cover crop post-harvest to deter nematodes living in the soil. Members of the Compositae family like Cosmos, black-eyed Susans and Asters, can also help other crops by attracting ladybugs that prey on insect pests.
Companion planting can be a tool in your organic toolbelt to improve your garden without the use of pesticides. The Three Sisters, thousands of years old, have grown together in harmony. This time of year, with the cool air and dark evenings, invite the Three Sisters in for a warm meal in their honor.
Consider adding this Three Sisters dish, published in the New York Times, to your upcoming Thanksgiving celebration.