Green beans look and taste pretty much the same whether they’re pole beans or bush beans. The difference is in the way the plants grow. Bush beans ripen all at once on short bushy plants. Pole beans are 5 to 8 foot long vines that twine up a pole or trellis and will produce beans over a two-month period.
A pole bean vine doesn’t grab onto things with tendrils in the way that peas do. Instead, the vines climb upward by spiraling around whatever they can find: bamboo poles, long wooden stakes or a trellis. If you provide a sturdy vertical support and keep the plants well picked, pole beans will usually produce for 6 to 8 weeks. You can sow about 8 pole bean seeds per square foot. As soon as the little plants break through the soil surface, they’ll be looking for something to climb on. For best results, put up your bean tower or trellis at the same time you plant your beans.
A bush bean seed will grow into a sturdy little 2 ft. tall plant. Each plant will produce for 3 to 4 weeks if you pick the mature beans every day or two. To extend your harvest of bush beans, sow a second crop in a different location, several weeks after planting the first crop. Once the plants stop producing, pull them out, put them in the compost pile and replant the area with a late summer or fall crop such as lettuce, beets or fall greens.
Both types of beans grow quickly from seeds planted directly into the garden. Wait for the soil to warm up to about 60 degrees before you plant beans and make sure any danger of frost has passed. Beans are most productive when they grown in full sun with approximately 1 inch of water each week. Like peas, beans are legumes and use nitrogen-fixing bacteria to absorb nutrients from the air. Inoculating the soil with nitrogen-fixing beneficial bacteria will improve vigor and yields. See the article on Peas for more about soil inoculants.
Bean plants are susceptible to a number of fungal diseases. For this reason, gardeners in cool, wet regions or places with high humidity, often have better luck with pole beans than bush beans. As a general precaution, try to keep bean foliage as dry as possible and avoid touching it when it’s wet with rain or dew. Good air circulation around the plants helps keep fungal problems in check, so avoid overcrowding.