Soil Nutrients for Pole Beans

Organic matter

• Pole beans benefit from added nutrients and improved drainage when you add compost to soil before planting. Organic matter such as compost breaks down gradually and adds the primary nutrients nitrogen, phosphorus and potassium to the soil. Compost also adds micronutrients that are not present in many commercially prepared fertilizers. Before you plant pole beans, spread 3 or 4 inches of compost over the planting area and mix it 6 inches into the soil. Grass clippings, straw and other organic mulch also add nutrients to soil.

Fertilizer

• If you have not tested your soil, work in 1 cup of general purpose “N-P-K” fertilizer per 50 row feet, 6 inches deep before you plant pole beans. Pole beans do not need high-nitrogen fertilizer because the plants fix nitrogen from the air, so you should use a low-nitrogen fertilizer with a 5-5-10 or similar ratio. If heavy rain washes the fertilizer from light or sandy soil, wait until flowering and pod set to apply 1 cup of 30-0-0 or equivalent nitrogen fertilizer per 50 row feet. Water lightly after you fertilize.

Other Sources

• Bacteria on pole bean roots help the plant obtain nitrogen from the air. Garden supply centers sell inoculant, which promotes the growth of this bacteria. Sprinkle the inoculant on the soil as you plant the beans, according to the National Garden Bureau. Micronutrient deficiencies may occur in soil that lacks organic matter or in soil with a pH above 6.5 to 7.0. Products are available to treat micronutrient deficiencies. For example, you can spray pole bean plants with a dilution of 1 teaspoon of iron chelate powder in 1 gallon of water if the plants develop iron deficiency symptoms such as yellow leaves with dark green veins.

Considerations

• Pole bean plants thrive in fertile soil, but generally should not receive heavy applications of nitrogen fertilizers. Excess nitrogen can cause the plants to grow abundant foliage with reduced bean pod production. If you apply fertilizer to the soil during the growing season, do not allow the fertilizer to touch the vine to prevent plant injury. Pole bean plants that do not receive adequate soil nutrients may produce deformed bean pods.