Snow Pea Agronomy Guide
A legume crop, snow peas are just one type of pea. Known for having an Asian, Chinese or oriental pod type, snow peas have edible pods, and they look thin and flat. Similarly, sugar snap peas have edible pods, but in contrast with a snow pea pod, a sugar snap pea pod is fleshier and round. English peas are another type of pea. Before they’re consumed, English peas must be shelled because the pods aren’t edible.
Buyers may consume raw snow peas, or they may prepare snow peas as a stir-fry ingredient. Growers have several marketing options when selling snow peas. Farmers markets, community-supported agriculture programs, produce auctions, local grocers, U-pick arrangements and roadside stands are all market opportunities.
Snow pea production sites demand good drainage. If a site doesn’t drain well, then the plants may be more susceptible to root and stem rot. Pea plants tolerate a range of well-drained soil types. Because sandy loams tend to warm up quickly, they’re often a good choice, and they may enable the operation to harvest peas sooner. Silt loams and clay loams also work well for snow pea cultivation.
Generally, avoid sites that have compaction problems, or address those problems. Compaction may minimize the extent to which roots can access oxygen and inhibit water from being absorbed well. With respect to soil pH level, 6.0 to 6.8 works well. Also, the selected site should follow a rotation. Fields that grew legumes in the previous three years shouldn’t be used for raising snow peas. Such a rotation can manage disease risk.
A soil test can inform a fertilizer application plan for growing sites. Depending on the test results, operations may need to apply phosphorus and potassium. If the soil is sandy, then applying preplant nitrogen may be beneficial. Adding too much nitrogen, however, may cause plants to fail in producing as many pods as they otherwise would have produced.
Boron is an important micronutrient that pea plants require. Distorted and empty pods are symptoms of a boron deficiency. Other nutrients of particular importance for pea production are calcium and magnesium.
If planting snow peas in cool, wet soil, then a starter fertilizer application can be effective. The fertilizer may help to counter reduced activity among nitrogen-fixing bacteria. Another option is a preplant broadcast fertilizer application that’s incorporated through disking.
Peas may be classified as determinate varieties or indeterminate varieties. Those considered to be determinate often don’t require a support structure, and their pods tend to concentrate near plant tops. On the other hand, indeterminate varieties require support from a double row or trellis. Often, peas that produce edible pods, such as snow peas, are those that grow as indeterminate plants.
Varieties also vary according to the amount of foliage that plants set. Some may have dense leaf cover, and others may have very few leaves. The latter type — known as leafless — can simplify harvest if serving wholesale markets. Additionally, snow pea varieties that offer a disease resistance benefit may be considered.
Snow peas will self-pollinate. As a result, operations may plant just one variety if they choose. The table lists several snow pea varieties available to producers. Of these, Oregon Giant has a mid-late maturity, and it produces large pods. Snowflake and Super Sugar Pod are recognized as having late-season maturities. The Snowflake variety is known for its dark green color, and Super Sugar Pod plants grow long vines.
Snow Pea Varieties
Dwarf White Sugar
Mammoth Melting Sugar
Oregon Sugar Pod
Short ‘n Sweet
Super Sugar Pod
Considered a cool-season crop, peas tolerate cool weather well. They may live through frosts and light freezes. Their blossoms, however, would be harmed by a frost or freeze. Time snow pea planting to when the soil warms to at least 45 degrees F. If the soil temperature increases to 75 degrees F, then germination will suffer. Plants prefer growing when temperatures range from 55 degrees F to 65 degrees F, and they don’t grow well if temperatures increase to warmer than 85 degrees F. As this suggests, waiting to plant a snow pea crop late in the spring may mean that the crop doesn’t have an opportunity to mature and produce a good crop before temperatures become too warm.
Before planting, producers may use water to soak snow pea seeds for about an hour. They may also apply a legume inoculant powder to seeds that have been soaked. If operations choose to use a granular inoculant, then one may be applied to pea seeds placed within rows. By providing inoculant to seeds, producers can increase the likelihood that pea plants form root nodules early in the production process. The nodules are responsible for converting nitrogen absorbed from the air into nitrogen that the pea plant can use. The inoculant would have particular value if planting in a site that hasn’t grown peas in the past.
Producers may choose to plant pea seeds in single or double rows. With a double row, one row may rely on its neighboring row for support. If an operation chooses double rows, then leave 6 inches between the two rows, and plant the next pair of rows 18 inches to 24 inches away. As another option, growers may plant snow peas in rows at 32- to 36-inch spacing. Within-row spacing may range from 1 inch to 2 inches. As for planting depth, roughly 1 inch is a target depth.
Operations also may plant snow peas at multiple iterations. The staggered planting would extend the snow pea harvest period. An extended harvest period would help to create a more balanced workload during harvest. Plus, staggering the planting would enable the operation to lengthen its marketing season.
Depending on whether operations choose determinate or indeterminate snow pea varieties, plants may require a trellis. Indeterminate varieties may grow taller than 3 feet. Not only would constructing a trellis encourage upward growth, but it would also permit air flow, enhance crop quality and boost yields. Good air circulation helps to dry plants, and dry plants may have a reduced incidence of developing mildew and other diseases.
Producers may build trellises from various materials, such as nylon mesh, twine, wire fencing and wooden stakes. The trellis should be added when the crop is planted. Installing the trellis early reduces the risk that pea plant root systems are harmed. If an operation plants indeterminate varieties in double rows, then the two rows being in close proximity may diminish the need for a trellis because the rows would rely on each other for support.
Without adequate moisture, pea plants may suffer and fail to produce a good crop. Just one period of moisture stress may have a negative effect on the pea crop. When pea plants are setting and developing pods, the crop particularly requires good moisture access.
If pea producers choose to install irrigation systems to supply sufficient moisture, then drip irrigation or overhead irrigation are options. Morning irrigation is preferable. Before sunset, plant leaves should feel completely dry. Water applied through irrigation should extend 6 inches deep. This will encourage a deep root system.
Weed pressure in a snow pea crop may limit the crop’s access to light, water, nutrients and space. Snow pea producers have several options to suppress weed pressure. For one, they may plant a cover crop to minimize problematic perennial weeds. Alternatively, for perennial weed control, snow pea producers may lay plastic mulch, apply herbicides or pull weeds by hand. Annual weeds may be managed through cultivation or hoeing.
Insects and Diseases
Several insect pests may damage snow peas: cutworms, wireworms, seedcorn maggots, alfalfa loopers, green cloverworms, aphids and armyworms. Other pests that may present challenges for pea operations include ear worms, stink bugs, leaf footed bugs, cabbage loopers, thrips, mites and root-knot nematodes.
If the snow pea growing area’s soils are wet, then the plants may be susceptible to damping-off and root rot. Several other diseases have the potential to infect snow peas. They include anthracnose, Ascochyta leaf spot and pod blight, powdery mildew, viruses, Fusarium wilt, bacterial blight and white mold. To prevent diseases from developing, pea seed may be treated, or fungicide treatments may be applied.
Harvest and Storage
At harvest time, look for flat snow pea pods. The seeds should be immature and small, and the pod should have a bright green color. Pods should measure 3 inches to 4 inches As a general rule, the snow pea harvest often follows planting by 60 days to 70 days and blooming by seven days. Prevent disease spread by only harvesting peas from dry plants.
Frequent harvests — perhaps as often as every other day — are necessary. Otherwise, producers risk that peas become too large, and pods can become tough. If snow peas aren’t picked on time, then they can be harvested and treated as English peas, which have the pods removed and the peas eaten. If overripe snow peas aren’t consumed as English peas, then they should at least be picked and discarded. Removing overripe pods is necessary to encourage pea plants to continue to bloom and produce pods.
Operations may choose to harvest snow peas by hand or machine. Employing workers to harvest snow peas by hand can be expensive. Harvesting snow peas by hand can also take significant time. To minimize harvest damage, harvest workers should use two hands as they pick the crop. With one hand, they should hold the plant and then gently pick pods with the other hand. Roughly pulling pods from plants may damage plants to yield-limiting levels or uproot the plants entirely.
Harvesting peas using mechanization has the potential to improve the production economics for large pea operations. However, snow pea producers have had somewhat little success with mechanized harvesting. A mechanical harvester would be a viable option if raising determinate peas. They don’t require a support structure, and they produce pods that concentrate toward plant tops.
After harvest, cooling the crop will help to retain its freshness and its sugar levels. Sugar contributes to snow pea flavor, so it’s an important component to preserve as best as possible. In storage, maintaining the optimal temperature is important because if temperatures are warmer than 32 degrees F to 34 degrees F, then the sugar in snow peas can convert into starch. At temperatures warmer than 34 degrees F, surface moisture can present a challenge. The moisture may cause peas to decay and deteriorate. The relative humidity in storage areas should range from 95 percent to 98 percent. Peas shouldn’t be exposed to ethylene because they may turn yellow and decay.
Even in ideal storage conditions, snow peas have a relatively short life. They may maintain their quality for roughly 10 days. During storage, peas may be placed in plastic bags to help promote storage life. Packing edible-pod peas in crushed ice may be used as a practice to enhance storage life. For the crushed ice to benefit storage-life extension as much as possible, the ice application should quickly follow harvest. Alternatively, operations may consider freezing peas to extend their useful life.
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