Yin yang beans get their title from their white and black coloring, which looks like the symbol for yang and yin. Also known as calypso or even orca beans, they are an backyard crop that can grow in almost any of the diverse microclimates of the Bay Area. For example, gardeners in warmer areas of San Francisco County can plant yin yang beans most of the year; at cooler Santa Clara County, planting season runs from April. These bush bean plants grow up to two feet high and prefer well-drained soil with complete sun exposure.
Until the soil in a sunny area and work a 2-inch layer of mulch to the soil to increase drainage and provide nutrients. Test the soil and, if needed, add sphagnum peat or ammonium sulfate to lower the pH level, or limestone to raise the pH level to 5.5 to 6.5. Add 1 cup of low-nitrogen fertilizer, such as 5-10-10, per 10 row feet. Keep away from high-nitrogen fertilizer, which results in heavy foliage with minimal or no bean production.
Plant yin beans in rows 2 feet apart when the soil temperature is between 60 and 85 degrees Fahrenheit. Plant 2 to 4 inches apart and the beans 1 inch deep. The bean plants should emerge in eight to 16 days and will grow within 75 days.
Water the yin yang beans lightly and keep the soil moist. To prevent fungus stains that are rust-colored, do not enable the leaves to become wet. You can supply around 1/4 inch of water a day to prevent the soil. Insert a layer of mulch to conserve moisture and protect the shallow root system of the plant.
Pull up weeds as they emerge round the bean plants. Be careful to not damage young bean plants.
Allow yin yang beans to dry on the plant, and harvest the beans when most of the leaves have turned yellow. Do not water the bean plants whereas the beans are still drying. Dig the plant up if the weather is moist and transfer it to a location that is sheltered. In dry, sunny weather, the beans should be dried within three to four weeks.