When to plant pole beans in Oregon City and West Linn, OR

Wait for warm soil

Bean seeds soak up water fast as they sprout, and in soil below about 60°F they swell but sit still, which gives rot fungi time to move in. In much of the west side that means waiting until late May or early June. A soil thermometer takes the guessing out of it.

Sow dry seed into moist soil instead of soaking it first, which can crack the seeds. If a spring is cold and wet, it's better to sow a week late than to resow a rotted row.

Trellis and feeding

Pole beans climb 6 to 8 feet, so build a sturdy trellis, teepee or fence before sowing; adding one later tramples seedlings. Beans twine on their own and just need something thin to wrap around, like string or netting.

Beans partner with soil bacteria that fix nitrogen from the air, so they need little fertilizer. Compost at planting is usually enough. Too much nitrogen gives lush vines with few pods. Steady water while flowering matters more, since dry spells make flowers drop.

Pests and problems

Slugs and bean seed flies attack seedlings in cool, damp springs; warm soil helps plants race past both. Aphids sometimes cluster on tips, and a strong spray of water knocks them back. In hot, dry eastern gardens, spider mites can speckle leaves yellow in midsummer, and keeping plants watered helps. White mold can show up in crowded, wet plantings, so give vines room and water at the base. Rotate beans to a new spot each year.