Select, or build, the types of support you will use for your runner bean plants to grow on. Bean plants need a good strong support of some kind. Choose between Maypole, Wigwam, Wall or Arch types. Attach strings to the top of pole and stake them to the ground in a tee-pee shape all around the central pole for the Maypole design. Staking cane poles or thin willow rods into the ground tied centrally together at the top is the Wigwam design. Tying together strings attached to a fence or wall in any design will produce the Wall support. Soften long strips of willow rods in water for several days. Push the rods deep into the ground and form an arch, giving you the Arch support.
Till up the soil where you are going to place the runner bean plants and add in compost, newspaper or organic matter. Runner bean plants need 2 to 3 feet of space between each plant in a semi-shaded area. Put down a black weed barrier film to ensure a very limited amount of weeds coming through. Inoculate the soil, after it has been tilled up, with a very small amount of fish, bone or blood fertilizer around the holes where your plants will go.
Soak your runner bean seeds on a plate with a damp paper towel covering them. As the seeds begin to swell and sprout, plant the seeds in the readied compost-rich soil after any threat of frost has passed.
Keep the runner bean plants well-watered until the first flowers are formed and throughout fruit set. Apply liquid seaweed to watering can or spray hose and water the plants low to the soil, not directly on the above plants. Cut off all stem growth, or growing tips, that grow at the top of your support to encourage more nutrients to go into the main plant below and give you more flowers and fruit. Weed and mulch around the runner bean plants daily or weekly to ensure the best growth for the plant.
Pick and harvest the pods once they reach 6 to 8 inches in length regularly to ensure ongoing production. Dig in your runner bean plant roots into the soil in fall or winter after the plants have stopped production and have died, to put extra nutrients in the ground for your next crop of vegetables the following spring.