April 01, 2020

Beans nature’s way of giving soil new life> Legumes act to replenish nitrogen, improve harvest

One of the most interesting horticultural phenomena is an activity of the botanical family leguminosae. As gardeners, we can appreciate the ability of members of this family — legumes — to take nitrogen from the air and, with the help of symbiotic bacteria, transform it into a useful form for plant growth.

A surprisingly wide range of legumes thrives in our climate. From the tall locust tree and the weeping Siberian pea shrub to the scarlet runner bean and the snap pea, members of this family grow large and small, woody and herbaceous. Aside from the outstanding nutritional value of some members of the family, we may use these plants as important components of a sustainable gardening system.

In our gardens, many different types of beans may be used in rotation with other plants to replenish naturally the soil’s nitrogen content. Planted in rotation with heavy feeders, such as corn, or even interplanted with such a crop, beans will “fix” nitrogen which will aid in the growth of subsequent crops.

Many Mediterranean, Middle Eastern and Far Eastern dishes are made with a variety of beans. The increasing popularity of these cuisines has drawn attention to the range of beans available. As a result, many seed companies have responded by offering many different types of bean seed to home gardeners.

Consider trying something other than the traditional wax and green beans in next year’s garden. Remember that, in general, beans should be direct-seeded. Some planting practices, such as starting transplants in paper or peat pots, will minimize transplant shock, but a better planting practice would be to direct-seed a variety that requires a shorter growing season than the straight species.

Of all the beans we are able to grow in Maine, the soybean, Glycine max, is among the most nutritious. The soybean is about 15 percent protein when fresh, 40 percent protein when dry. Two types of soybean grow well in the Maine garden: green and black. Green soybeans are tender, easy to digest and have a pleasant, buttery taste. They are generally eaten fresh, but may be frozen for the winter months. Black soybeans, on the other hand, are perfect for drying and storage. They, too, are flavorful.

Soybeans are used in making tofu, soy milk and vegetable oil. They are an important component in cattle feed. A group of farmers in central Maine has experimented with growing the crop commercially in rotation with potatoes exactly for this purpose. We may eat soybeans green, if boiled, or we may dry them for use in soups and casseroles.

Once they have set on the plant and filled out in size, most soybean pods ripen quickly and at the same time. The trick to harvesting the crop is to time it so that the beans are fully ripened without having been sampled by local deer. “Sampled” is an understatement: Deer will flatten your crop. This delectable bean is a special treat to these critters which, in past years, have been the biggest garden pest to soybean planting. Otherwise, soybeans are easy to grow and tend, if planted immediately after the danger of frost has passed.

The garbanzo bean, or chickpea, is another extremely nutritious member of the bean family. This hearty bean is the backbone of many Middle Eastern soups, salads and main dishes. It is the major ingredient in hummus.

Cicer arietinum, as the chickpea is known botanically, prefers to be grown in a warm and dry environment. Thus, the plant can be grown with success in some Maine summers, but will fail in summers that are foggy or wet.

Each chickpea plant bears only a couple of beans, so quite a few plants must be grown to produce a substantive crop. Taking more than 100 days to mature, this bean must be planted early in the season to ensure enough time to provide a crop.

The lima bean, referred to in various sources as both Phaseolus limensis and Phaseolus lunatus, may be either a pole variety or a bush variety. The lima bean is a prolific plant and, although it has only about half the protein content of the soybean, it is still highly nutritious.

Eaten fresh or stored frozen, the lima bean is perfect for eating alone or in casseroles. The flavor of this bean is similar to that of the soybean. The bush-type lima bean is the best to grow in Maine and prefers warm weather. The seeds must be sown directly into the soil once the temperature is about 70 degrees.

If waiting for next summer to grow beans seems too far off, perhaps you’d like to try your hand at growing the mung bean, Vigna radiata, for sprouts. The sprout of this bean is used in Chinese cooking, namely in stir-fry and chop suey. The seeds are quick to produce large, hearty sprouts.

Diana George Chapin is the NEWS garden columnist. Send horticulture questions to Gardening Questions, c/o Maine Weekend, Bangor Daily News, P.O. Box 1329, Bangor 04402-1329. Selected questions will be answered in future columns. Include name, address and telephone number.

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