Legumes - The Manual of Seed Saving - page 127

nitrogen from the air for the corn, a harmonious symbiosis between plants not unlike the milpa grow-
ing techniques of Mesoamerica. The practice of growing corn and beans together is also found in
southern Austria, Croatia, and many other countries of southeastern Europe. Two varieties of this in-
between growth habit hail from Switzerland: 'Schwefleren' (a yellow shell bean) and 'Schnutzla'.
WHAT YOU'LL NEED
• at least 10 healthy, high-yielding plants
• a climate allowing for full ripening of beans
• for pole beans: poles or trellises
POLLINATION NOTES The common bean almost exclusively self-pollinates, with pollination usually
taking place before flowers even open (cleistogamy). Specialist literature indicates cross-pollination
rates of no more than 1%. In areas where flowers are few and far between (and especially when bees
are active), cross-pollination is much more likely (up to 20%!). Bumblebees in particular can bite
flower buds open and cause cross-pollination. Carpenter bees ( Xylocopa spp.) and other large insects
are able to force their way so far into the flower bud that they reach the style and pollinate it. Isolation
distances of 15-30 ft. (5-10 m) between varieties are in any case recommended. Cross-pollination is
evident on pods and beans the first year; remove those that are not true-to-type.
Pods of various bean cultivars
Bean flowers can be white, cream, violet, or pink, depending on the variety. Plants bloom for 20 to
26 days. Flowers open from about 6 to 10 o'clock in the morning, and once they are open, they stay
open.
GROWING FOR SEED Because common beans originated in subtropical and tropical regions, they are
highly frost sensitive, so do not sow seed until after the last spring frost. Beans require temperatures of
at least 46°F (8°C) to germinate. Pre-soaking beans before sowing is usually not recommended, as
seed may rot in cool, wet weather or seedlings may desiccate in dry weather. When tall enough, soil
can be hilled up around the base, especially around bush beans, to improve stability.
Beans germinate faster with higher temperatures. The faster they germinate, the less likely they are
to be affected by damping off or other fungal diseases. Quick-germinating seeds are also less likely to
be nibbled on by the larvae of bean seed flies ( Delia florilega and D. platura ). They are typically the
cause of missing cotyledons and eaten-away-at stems. Algal limestone can be lightly applied or algal
extract can be used in watering as a preventative measure. Beans should be planted flat and shallow, so