Last modified January 11, 2010
VARIETIES (approximately 80 to 100 days in lower Columbia Basin).
Very few lima beans are grown for fresh market in the Pacific Northwest. When grown for processing, varieties are specified by processor. Commercial lima bean production has generally been limited to east of the Cascade Mountains. Some varieties grown east of the Cascade Mountains are:
Small-seeded types: Packer DM (early), Maffei 15, Early Thorogreen, Kingston, Thaxter, Clarks Bush, Baby Lima, Wasatch.
Large-seeded types: Fordhook 242.
Pole types (for specialty fresh market and home garden): King of the Garden, Large Speckled Christmas Green.
Others for trial: Eastland, Baby Fordhook.
Lima beans are adapted only to the warmer areas of east of the Cascades such as the Columbia Basin and Treasure Valley.
Lima beans grow best on medium to light, loamy soils that are well drained and well supplied with organic matter. Lima beans can develop vigorous, extensive root systems.
Avoid fields that are stony or that have a history of high weed populations, especially quackgrass. Select fields that are uniform in fertility, soil type, slope and drainage. Rotate crops to minimize root damage from root rot diseases and avoid fields that had crops where white mold (Sclerotinia sclerotiorum) was a problem. Determine corrective lime and fertilizer rates by a soil test.
In general, pH should be at least 6.5. In fields with no recent history of lima bean production, seed will need to be properly inoculated (see below).
Lima beans are planted in the lower Columbia Basin from about mid May to mid June after soil temperatures exceed 65 to 70 F. Ideal germination is at soil temperatures of 75 to 85 F. Soil temperatures below 60 F result in poor stands and poor early growth.
Lima bean seed is sensitive to damage from cold water imbibition, particularly when the seed is very dry. To reduce risk of cold water imbibition damage condition the seed to 12-14% moisture before planting. This may be done by opening seedbags and placing them in a protected area to absorb moisture from the air several days before planting. Stand establishment is one of the major limiting factors in lima bean production.
Lima bean seed numbers approximately 25-75/ounce for large-seeded and small-seeded types respectively. Use only fungicide and insecticide-treated seed.
Use a plant spacing of 3-4 inches within row and 22 to 36 inches between rows. Use the wider spacings for large-seeded limas. For baby limas, a spacing of 3 x 22 inches would result in approximately 95,000 plants/acre. At about 1300 seeds/lb, approximately 73 lb seed/acre would be needed. For large limas, a spacing of 4 x 36 inches would result in about 44,000 plants/acre. At 500 seeds/lb, about 88 lb seed/acre would be needed.
Seeding rates would have to be adjusted upward from these figures to take into account actual seed count, germination percentage, and expected seedling mortality.
Inoculating seed before planting is recommended when limas are to be grown on soils on which limas have not been grown before. Strains of inoculum specific for limas should be used. Consult your seed supplier for the appropriate strains and inoculation methods. Inoculum should be fresh and should be applied just before planting.
For the most current advice, see Nutrient Management for Sustainable Vegetable Cropping Systems in Western Oregon, available as a free download from the OSU Extension Catalog
The following recommendations are for east of the Cascade Mountains. It is recommended that a soil test be done for each field to be planted.
Nitrogen: 60-100 lb total N per acre. Base pre-plant application, if any, on residual soil N. If a pre-plant application is needed, apply only 20-30 lb N/acre so as not to interfere with root nodulation. Adjust supplementary applications to stand, crop vigor and seasonal conditions. Thirty-five to 40 days after planting, prior to an irrigation, sidedress another 30-60 lb N/acre. An additional 30-40 lb N/acre may be applied at bloom if needed. Avoid excessive N since it may cause rank growth, delayed flowering and increased incidence of mold.
Phosphorus: 70-80 (P2O5) lb/acre
Potassium: (K2O) not needed in most cases in the production areas east of the Cascade Mountains.
Sulfur: 5-15 (S) lb/acre
Zinc: 5-15 (Zn) lb/acre
It is best to plant lima beans into moisture and avoid irrigation until the stand has been established. Manage water applications carefully to avoid excessive vegetative growth before bloom. From 20-25 inches of water may be needed depending on seasonal variation, variety, and planting date. Approximate summer irrigation needs for the Hermiston area have been found to be: 3.5 inches in May, 5.0 in June, 7.5 in July, and 7.0 in August.
Soil type does not affect the amount of total water needed, but does dictate frequency of water application. Lighter soils need more frequent water applications, but less water applied per application.
HARVESTING, HANDLING, AND STORAGE
Lima beans are harvested in the Columbia Basin from about mid-August to mid-September. The prime harvest season is from about the first of September to mid-September. Average yield of baby limas is approximately 2000 to 3000 lb/acre.
The harvest date is scheduled by the processor. It is helpful to know the predicted maturity date for each variety, but these dates will vary from year to year because of climatic conditions. A general rule of thumb is that a field with 10% of the pods "dry" will produce ample yields with good quality still available.
For harvest, the rows are cut with either rotary cutters or knives, and windrowed, and then picked up by mobile viners for threshing. The new "pod-picking" harvesters used in peas are now also being used for harvesting limas for processing. These eliminate the need for swathing and windrowing.
Lima beans for fresh market are most often hand harvested, but new mechanical harvesters are also available that harvest pods intact.
STORAGE (Quoted or modified from USDA Ag. Handbook 66 and other sources)
For fresh market, store lima beans at 37 to 40 F and a relative humidity of 95 %. Lima beans are highly perishable and also sensitive to chilling injury, so they are precooled, preferably by hydrocooling, immediately after harvest and kept at a low temperature. Pods are more sensitive to chilling injury than the beans, so the unshelled beans should be kept at 40 to 43 F.
Shelled beans can be kept at 37 to 40 F. At these temperatures, the loss in quality resulting from the combination of normal deterioration and chilling injury is less than that due to either normal deterioration at higher temperatures or chilling injury at lower temperatures. Injury and deterioration of pods are indicated by rusty-brown specks and spots that increase sharply at 70 F, and shelled lima beans become spotty and sticky. Unshelled lima beans can be kept for about a week at the respective suggested temperatures.
Shelled lima beans are sometimes stored in perforated polyethylene bags. An atmosphere of high carbon dioxide content is desirable. For example, one with 25 to 30 % carbon dioxide reduces stickiness and spotting of seeds by inhibiting fungal and bacterial growths. The effect of a low oxygen atmosphere has not been reported.
Limas should be used promptly after removal from refrigeration as the pods discolor rapidly at room temperature.