When to plant bush beans in Leavenworth, WA

Why cold soil kills bean seeds

Bean seeds need soil of at least 60°F to sprout, and about 80°F is ideal. In cold, wet soil, dry seeds absorb water so quickly that their tissues are damaged, and soil fungi then rot them before they emerge. That's the most common bean failure in the Northwest. Use a soil thermometer and wait for 60°F. Don't soak bean seeds before planting, since that can cause the same injury. Provider is noted for sprouting better in cooler soil.

Beans make their own nitrogen

Beans partner with soil bacteria called rhizobia, which live in small nodules on the roots and turn nitrogen from the air into a form the plant can use. Active nodules are pink inside. Because of this, beans need little nitrogen fertilizer, and heavy feeding mostly produces leaves at the expense of pods.

In a bed that hasn't grown beans before, coating seeds with a bean inoculant (a powder containing the right bacteria) at planting time helps nodules form.

Soil and water

Beans grow best in loose, well-drained soil with a pH of about 6.0 to 7.0. Keep the soil evenly moist once flowering starts. Drought or heat above about 90°F during bloom causes flowers and small pods to drop, which is more common east of the Cascades.

Disease

Bacterial blights and white mold spread easily on wet leaves. Water at the base, give plants room for airflow, and avoid working among them or picking while the leaves are wet, since you can carry bacteria from plant to plant on your hands.

Harvest and storage

Pick snap beans when pods are about as thick as a pencil and before seeds bulge. Once seeds start to mature, the plant slows down, so frequent picking keeps it producing for weeks. Store in the fridge and use within about a week.