Plant snap beans when soil warms to sixty degrees

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Last Updated: 
June 1, 2006

Green beans photo by Lynn Ketchum, OSU Extension Publications
CORVALLIS - Snap beans you buy in the supermarket cannot compare to the crisp, fresh and flavorful beans you can grow yourself at home. When seed companies and plants people say "snap" beans, most usually are referring to all types of fresh garden beans – wax, green, and French or Roma types.

Whether they grow on vines or shorter bushy plants, snap beans germinate best in soil at least 60 degrees, from about late April through June. They will germinate at about 50 degrees, but at this cool temperature bean seeds tend to crack, allowing microbes access, explained Jim Myers, Oregon State University's Baggett-Frazier Professor of Vegetable Breeding and an expert on beans.

White-colored bean seeds are particularly sensitive to cracking. Myers recommends planting colored bean seeds if you are planting them before the soil has warmed up to 60 degrees. The food processing industry prefers white-seeded green beans to colored beans, as the colored beans may stain their processed products.

The best way to make sure the soil has warmed up enough is to buy a small thermometer. Then you can be positive you are planting at the right time.

"Germination and emergence definitely improves as the soils warm up into the spring," said Myers. "And the risk of damping off, caused by a fungal infection, drops off as soil temperatures rise."

For successive summer crops, plant snap beans all the way through June. Plant one more batch in early July and you may get a fall crop, if you live where frosts aren't too early in the fall.

Bush beans were bred to save the cost of putting up trellises for pole beans and to allow mechanical harvest. Many of the varieties grown commercially in the Pacific Northwest were developed by Jim Baggett, an OSU emeritus professor of horticulture.

Bush beans include the French filet beans, also known as "haricots verts." These are coveted by gourmets and harvested at a young age, when the pods are no more than a quarter-inch in diameter. Generally, bush beans planted at the same time ripen at the same time, so are good for freezing or making batches of canned or dilly beans.

Some seed catalogs and garden stores sell legume inoculant, advertised to help beans grow, but according to Myers, it is not necessary.

"Inoculant helps only when going for super yields or if you are planting beans into a soil that has never had beans before," said Myers.

Otherwise, Rhizobia, the symbiotic bacteria that lives on legume roots, producing nitrogen, should already be present in the soil.

Plant bush bean seeds two to three inches apart and one inch deep in rows 18 to 36 inches apart in a sunny, well-drained area. If you live on the east side of the Cascades where your soil may be drier and hotter, try planting them a little deeper, suggests Myers. Bush green beans are ready to harvest about three weeks after flowering. Keep plants picked for more production.

Pole beans need a trellis or other support and keep producing beans over a longer period of time. Pole beans produce more per area of garden space, but cast a larger shadow than bush beans.

Snap beans have some vocabulary words all their own. The term "Roma" refers to a flattened pod type snap bean. "Blue Lake" beans are long, straight and uniformly shaped green beans that were bred for the food processors. "Wax" beans are green beans with yellow pods. All these types of beans are considered snap beans.

Lima beans, soybeans, scarlet runner beans, and fava beans are other species and not considered snap beans. Dry or field beans, the same species as green beans, are harvested for the inside bean, not the pod.

The OSU Extension Service recommends the following varieties of green beans as performing well in Oregon conditions:

(green bush) Tendercrop, Venture, Slenderette, Oregon 91G, Oregon Trail, Provider, Jade, Oregon 54.

(flat Italian) Roma II.

(French filet) Nickel, Grenoble.

(green pole) Blue Lake, Kentucky Wonder, Romano, Cascade Giant, Kentucky Blue, Oregon Giant.

(wax bush) Goldenrod, Goldrush, Indy Gold, Slenderwax.

Beans are subject to several viruses and root disorders and white and gray mold. Avoid over watering to reduce the risk of root rots. Avoid watering that prolongs the wetness of the foliage. Remember to remove dead plants at the end of the year. And don't forget to rotate your crops from year to year.

Myers suggests that Oregon gardeners buy snap bean seed from a western company, to avoid seed borne bacterial blights.

"Most established seed companies, including those in the east sell western-grown seed. Some smaller eastern operations might not."

Author: Carol Savonen
Source: Jim Myers, Deborah Kean