If you're a vegetable gardener or you're thinking of starting a vegetable plot for the first time, don't overlook green beans (Phaseolus vulgaris) when deciding what to plant. Green bean plants have two types of growth habits, either growing as short, bushy plants -- bush beans -- or as long vines that need support, called pole beans. Both types grow as annuals in all parts of the United States and thrive when given lots of sun, well-drained soil and a bit of extra care during the season.
The first step in growing green beans is deciding whether to grow the bush type, which tolerate moderately hot or hot summers well, or pole beans, better suited to cooler summers. Pole beans also need support, such as a trellis, to keep their long vines from trailing on the ground; because they grow upward, they're well-suited to a small garden where space is tight, yielding two or three times more that bushy plants grown in the same area.
Green bean plants are frost-sensitive and germinate faster in soil that's above 60 degrees Fahrenheit, so wait to plant until all danger of spring frost has passed and the soil has warmed a bit. Set seeds about 1 inch deep and, for the best yield, choose a spot that gets full sun for most of the day and has well-drained soil. Space seeds of bush beans 2 to 4 inches apart, with rows about 2 feet apart. Pole beans need 4 to 6 inches between seeds, either in hills with six seeds each and 30 inches between hills or in rows spaced 3 feet apart.
Providing Water and Fertilizer
Green beans don't do well with constant, heavy moisture or soil that stays soggy, so water the seeds after planting and then give some extra water whenever the soil's surface feels dry to the touch, aiming for 1 inch of water weekly, including rain. Water early in the day so foliage dries quickly, to avoid fungal problems and, once seedlings emerge, add 2 inches of organic mulch to help conserve soil moisture and keep down weeds.
Green bean plants don't require fertilization, and using high-nitrogen formulas can decrease yields. For best results, mix 1 or 2 inches of compost into your soil before planting seeds; this increases the soil's organic content and boosts its general fertility.
Extending the Harvest
If you have extra space in your garden, you can extend the green bean harvest by making successive seedings every two to four weeks until mid- to late-summer. Most cultivars produce green beans between 58 and 65 days after planting, with some variation depending on the variety. Pick pods when they're firm and elongated, but before you see bulges from ripening seeds inside the pods. Pick beans regularly, every day or two, or whenever you see new pods appear; this keeps the plants flowering and making new pods.
If you want to save seeds from your plants, allow some pods to stay on the plant until the outer covering is thin and dry and large seeds are inside. Remove these, let them dry for a day or two, and store in a paper envelope in a dry spot until the next year.