Richard Ebesu, PEPS Dept.
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Beans generally grow well in Hawaii¹s warm climate. The most common beans found in home gardens are types of green bean (also called snap or string bean) grown for eating as a vegetable. These include numerous green bean cultivars of Phaseolus vulgaris, yardlong bean or asparagus bean (Vigna unguiculata sesquipedalis), lima bean (Phaseolus limensis), and, occasionally, yellow or wax bean (also P. vulgaris varieties). Both bush and pole types of green beans can be found, with either flat or rounded pods. Most are grown for harvest and preparation of the entire young pod, although the limas are often shelled before cooking. Some lesser known beans that occasionally are found in home gardens in Hawaii and can be consumed as snap beans include the rice bean (Vigna calcaratus), winged bean (Psophocarpus tetragonolobus), lablab bean (Lablab species), and sword bean (Canavalia species). The bean types used for dried beans, such as navy, kidney, pinto, garbanzo, mung, adzuki, and others, are not commonly grown in Hawaii.
Pole bean varieties are usually preferred in home gardens because they yield more for a given space and over a longer period of time. Most gardeners in Hawaii prefer the long, flat-podded types. Three pole bean varieties have been developed by UH-CTAHR for disease resistance. Hawaiian Wonder¹ is resistant to fungal rust disease in some areas and should be planted if rust is a problem. Poamoho¹, which is stringless, and Manoa Wonder¹ are resistant to infection by the root-knot nematode. Other pole bean favorites include the Mainland types Kentucky Wonder¹, with long, somewhat rough pods, and Blue Lake¹, with shorter, round pods. Blue Lake¹ also has bush variants.
Greencrop¹ is a flat-pod bush bean that has been grown successfully in Hawaii. Magnum¹ is a bush type that has done well in trials and produces large, flat pods. Greencrop¹ and most other bush beans are resistant to rust disease. Most bush bean varieties found in seed catalogs produce short pods that are round in cross-section. Lima beans also come in pole (King of the Garden¹) and bush (Fordhook 242¹, Henderson Bush¹) varieties. Both large- and small-seeded varieties can be found. Pole lima beans are essentially perennial in Hawaii if kept free of pests and diseases. ³Yard-long beans² are long-podded pole beans similar to the shorter-podded bush versions called black-eye pea or cowpea.
Bean plants grow best in well drained, moderately acidic to neutral soil (pH 6.0 to 6.8 is optimum) with a good level of soil organic matter. Have the soil analyzed to determine the soil pH and whether any soil amendments (including lime, dolomite, and phosphate) are needed. A soil analysis is particularly recommended for new garden sites. A ³standard² soil analysis, which measures soil pH and available soil phosphorus, potassium, calcium, and magnesium, is relatively inexpensive and can be done by the CTAHR Agricultural Diagnostic Service Center** or a commercial laboratory (preferably one having experience with Hawaii¹s soils).
Soil with pH below 5.5 requires application of agricultural lime to increase the pH to a level more favorable for plant growth. Soil in high-rainfall areas often requires lime to increase the calcium supply.
Low levels of available soil phosphorus limit plant growth in many of Hawaii¹s soils. Both lime and phosphate fertilizer must be mixed thoroughly into the surface 68 inches of the soil before planting.
Home garden productivity can usually be increased by amending the soil with organic matter, such as compost or well rotted animal manure (see the CTAHR publications Backyard compostingrecycling a natural product and Composted animal manuresprecautions and processing). If a suitable material is available, make an annual application to the garden of 13 inches spread over the soil and mixed into the surface 68 inches. If the material is in short supply, its application can be limited to the area within 610 inches from the planting row or spot.
To ensure adequate levels of the major plant nutrients, include a general fertilizer when preparing the garden before planting. Commonly available rapid-release fertilizer formulations suggested for vegetables are 16- 16-16 (³triple-16²) and 10-20-20 (these numbers refer to the percentages of nitrogen, phosphate, and potash in the fertilizer). Commercial growers often figure on applying a total of 150 pounds of N per acre to a bean crop. On a 100 square-foot (sq ft) basis, this is equivalent to two applications (one preplanting, the second to the bearing crop) of 134 pounds of 10-20-20 or 1 pound of 16-16-16 per application. Gardeners who prefer to use slow-release formulations will apply all of the nutrients before planting. Preplanting fertilizers should be mixed well with the garden soil.
Soil phosphorus can increase to an undesirably high level after long-term application of high-phosphate fertilizers, such as 10-30-10. If this is part of the garden¹s history, a soil analysis should be done to check the phosphorus level. If it is in excess, a zero-P formulation can be created by mixing equal amounts of urea and muriate of potash to produce a formulation that is about 23- 0-30. For the 100 sq ft basis fertilizer schedule mentioned above, about 34 pound of this fertilizer would be applied in each of two applications.
When the plants begin to flower, apply the second dose of general fertilizer. Divide the amount of fertilizer being applied into small doses according to the number of plants in a 100 sq ft garden area. Apply each dose 68 inches from the base of each plant. Some gardeners spread the fertilizer on the soil surface, but others believe it is best to use a trowel to incorporate it 24 inches into the soil in one or two spots, using care to minimize damage to the plant root system. Irrigate after the application.
Instead of a single postplanting application, some gardeners divide the amount into two applications, the second made two to three weeks after the first. Others will apply smaller amounts of fertilizer every two weeks after bearing begins. Water-soluble fertilizers with micronutrients may also be used for postplanting applications.
Plant seeds directly in the soil about 1112 inches deep. For pole beans, seeds can be planted 612 inches apart on both sides of a trellis or fence. Allow 3640 inches between rows of pole beans. Most pole bean varieties form vines 23 weeks after emerging. Train the vines to climb the support instead of crawling on the ground. Bush beans can be planted 46 inches apart in rows 30 inches apart. Pole lima beans can produce huge vines and need wider spacing and a sturdy fence for support.
Irrigate as necessary to maintain available soil moisture, but avoid soil waterlogging. Any setback early in their growth may result in smaller, weaker plants with reduced yields. To minimize leaf disease, avoid wetting the plant when applying water. If possible, irrigate only the soil using furrows, drip lines, or soaker hoses. If using overhead (sprinkler) irrigation, do it in the morning so the plants dry quickly as the day warms.
Gardeners may find several pests on beans. The bean fly lays eggs on the first leaves shortly after germination, and the maggot tunnels down the stem to the first node. The damage thus caused to the plant¹s vascular system results in wilting and dying of the top of the plant.
In areas severely infested with bean flies, weekly insecticide applications may be necessary from seedling emergence until flowering. Mature plants usually tolerate bean fly infestation without further applications of insecticide.
Cutworms and slugs hide during the day and feed on the stems near the soil at night. Collars several inches high stuck into the soil around the stem can deter cutworms, and regular disposal of slugs removed from their hiding places will reduce their damage. Chinese and Fuller rose beetles chew the leaves, and leafminers tunnel into the leaves, leaving white trails. Aphids, whiteflies, and mites suck the plant sap and may be controlled with insecticidal soaps. Occasionally, pod borers infest the inside of the pods, and stink bugs puncture the pods. When using pesticides, read the label to ensure that the intended use is included on it, and follow all label directions.
The most common diseases of beans in Hawaii are rootknot nematodes, which invade the roots, and the diseases rust, anthracnose, and halo and bacterial blights, which affect the leaves. These foliar diseases are more prevalent during prolonged periods of wet weather, and they rarely are a problem in dry areas. Irrigating only the soil and keeping the leaves dry will help reduce incidence of foliar diseases. When possible, use nematode- resistant varieties such as Poamoho¹ and Manoa Wonder¹ and rust-resistant varieties such as Hawaiian Wonder¹ and most bush beans. Soil solarization and incorporation of manure or compost may help to reduce populations of nematodes in the soil
Green beans are usually harvested just before the seeds start to swell and become visible as bumps on the outside of the pod. For most varieties, this usually occurs about 10 days after flowering or about 6 weeks after planting. Most of the pods of bush bean varieties mature around the same time, during which two to four harvests can be taken.
Pole beans continue to produce as long as the plant remains healthy. Regular harvesting of the beans promotes further flowering. Lima beans are harvested when the beans reach full size but before the pods start to turn yellow.
Seeds of Hawaiian Wonder¹, Manoa Wonder¹, and
Poamoho¹ are available from the CTAHR Agricultural
Diagnostic Service Center Seed Lab on the UH Manoa
campus and from some garden stores. Other varieties
can be found in garden stores and seed company catalogs.
CTAHR Seed Lab order forms can be obtained
online at
Useful CTAHR publications for the gardener include
Testing your soilwhy and how to take a soil-test sample
and Plant-parasitic nematodes and their management.
Find these and other titles at
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