Cucumber Agronomy Guide
As a crop that originated from India, cucumbers belong to the Cucurbit family. The crop wasn’t the focus of hybrid breeding efforts until 1880. Originally, cucumbers didn’t have the smooth or symmetrical characteristics typical of varieties available today. When growing cucumbers, producers can choose varieties have attributes well-suited for either pickling or fresh consumption markets. “Slicers” is an alternative term for cucumbers meant for immediate consumption. The slicing cucumbers have thick, uniform, dark green skins. With thick skins, slicing cucumbers may experience less handling- and shipping-related damage. Relative to cucumbers used for processing, the slicing varieties generally produce longer fruit. This guide specifically addresses production factors for slicing cucumbers.
Cucumber planting sites should have several characteristics to encourage good production. First, the site requires soil that can hold water and support good water infiltration. Soil also shouldn’t have compaction problems. Other site selection considerations include choosing areas without triazine herbicide residues and those that recently haven’t grown related cucurbit crops like melons and pumpkins. High organic matter is another desirable attribute of soils in cucumber planting areas.
During the growing season, cucumbers prefer temperatures that range from 65 degrees F to 95 degrees F. Temperatures cooler than 50 degrees F or warmer than 95 degrees F will compromise cucumber growth and maturity . If temperatures are too high, then cucumber varieties may produce fruit that has a light green color or bitter flavor.
To gauge soil fertility needs, conduct an annual soil test, and design a fertility program based on the results. During the growing season, producers can identify whether plants have additional nutrient needs by testing and analyzing plant tissue and petiole sap. From a soil pH perspective, the ideal pH level for cucumbers would range from 5.8 to 6.6. Producers growing slicing cucumbers could provide fertilizer through banded applications at planting and drip irrigation applications as the plants grow. As a general rule, slicing cucumbers require nitrogen, phosphorus and potassium at 30-50-50 pounds per acre both when banding fertilizer at planting and supplying fertilizer during the growing season with a drip-irrigation system. Adjust these general recommendations based on soil test results.
Some varieties offer seedless, parthenocarpic characteristics. Those varieties don’t require pollination. Gynoecious varieties only produce female flowers. Such varieties produce a more concentrated fruit set, and they record earlier production. Choose varieties that satisfy buyer specifications. The following table shares slicing cucumber varieties listed in the Midwest Vegetable Production Guide for Commercial Growers. Of these, three varieties produce fruit very early. The table also includes an early-season and main-season variety.
Recommended Slicing Cucumber Varieties
When planting cucumber seed, wait until the soil has warmed to at least 60 degrees F, and avoid planting before night-time air temperatures have warmed to at least 50 degrees. To get an early start, cucumber growers can choose to use transplants, which would be grown in a greenhouse for 18 days to 24 days before planting. For transplants, plant cucumbers after soil temperatures have warmed to at least 60 degrees F at a 3-inch depth. To facilitate drainage and enable the soil to warm, growers can use raised beds, which may measure 6 inches tall.
If planting seed, then choose seed that has had fungicide and insecticide treatments. Seed planting depth will depend on planting season timing. For spring-planted seed, use 0.5- to 1-inch planting depths, but for a fall crop, increase the planting depth to 1 inch to 1.5 inches. If growers plant seed densely, then they need to thin the stand before plants have reached the four-leaf stage.
A planting area designed to feature raised beds, plastic mulch and drip irrigation would help to support good growth and high yields. Ideally, an area needs good moisture levels before laying plastic mulch. When planting single-row slicing cucumbers on plastic beds, allocate 9- to 12-inch spacing between plants. Rows should be positioned at every 4 feet to 5 feet. In a model like this, the plant population will range from 8,400 plants per acre to 10,500 plants per acre. In a two-row bed model, allow for 18-inch spacing between rows.
Cucumbers will also grow in high tunnels. Varieties well-suited for high tunnel production are those with the parthenocarpic and gynoecious characteristics. When designing the production area, allocate 4 feet to 6 feet in row spacing, and with respect to plant spacing, allow 12 inches for single rows and 24 inches for double, staggered rows. At one week to two weeks before planting, lay black plastic mulch, which will increase soil temperature, minimize moisture loss and reduce weed pressure. Installing drip tape will supply adequate moisture. To plant cucumbers in high tunnels, use transplants, which can grow up a mesh trellis. Parthenocarpic varieties may be pruned to a single leader and trained. Note that pest pressure can influence high tunnel cucumber production, and to manage disease risk, choose disease-resistant varieties, space plants properly and provide adequate ventilation.
Cucumber producers may need to add a honey bee hive to the growing area. For seedless, parthenocarpic cucumbers, pollinators aren’t necessary. However, in other varieties, adding a hive can encourage pollination and fruit set. Female cucumber flowers may only receive pollinators during the morning and early afternoon. Without good pollination, cucumber plants may produce misshapen fruit. If adding beehives to cucumber production areas, then set up one per acre. Pollinators like honey bees may be harmed by insecticide applications. To avoid harming pollinators, plan evening insecticide applications. Ideally, wait until after 4 p.m. By removing or covering hives during spraying, the pollinators would be less affected by spray drift.
Cucumber producers can realize benefits from training or trellising cucumber vines. Training vines to grow within a row lengthwise may simplify hand harvesting and cause less harm for plants. When growing cucumbers on a small scale or planting for a fall harvest, producers may consider trellising cucumbers. When cucumbers grow on a trellis, they may yield higher quality fruit. However, using a trellis will demand additional labor and supplies.
While growing, cucumbers need reliable water provided to them. Water constitutes 90 percent to 95 percent of cucumber fruit. At shallow depths, the plants tend to have many roots. If moisture levels fluctuate too much or are inadequate, then cucumbers may suffer from growth deformities. A good water supply is especially important during cucumber fruiting. Typically, cucumber water requirements are about 1 inch per week. During fruiting, water needs may increase to 2 inches per week. The higher water requirements may be especially necessary when the weather has turned hot and dry, the crop has had exposure to windy conditions, or the crop grows in a sandy site.
Using drip irrigation would provide consistent water to cucumber plants, and these systems could also administer fertilizer applications. Drip irrigation also prevents water-splash that could trigger foliar diseases.
Several strategies can help cucumber producers to address weeds. Adopting a good crop rotation, applying herbicides and laying plastic mulch are options. Before cucumber vines start to run, cultivation can address weed issues. The mechanical cultivation would need to be shallow to avoid disturbing roots. Plant growth and fruit yield would suffer if equipment prunes plant roots and vines. As another alternative to control weeds, producers may use hand hoeing.
Insects and Diseases
A good practice to minimize pest or disease pressure involves scheduling field scouting at least weekly. Regular scouting would also identify weed problems in cucumber fields. By tracking insect activity, producers can gauge the need to spray to control the pests. Insects that can damage cucumber crops include cucumber beetles, aphids, cutworms, seed corn maggots, leafminers and mites. Squash vine borers are another insect threat for cucumber producers. When cucumber plants are young, adult striped and spotted cucumber beetles could cause damage. Cucumber beetle infestation creates a risk because the beetles act as a bacterial wilt vector.
Nematodes may also pose a risk to cucumbers. To gauge nematode pressure, producers can take a nematode assay by field. Using a fumigant-type nematicide can address any problems discovered during testing.
Diseases can infect roots and foliage of cucumber plants and the fruit itself. Specific diseases that may affect cucumber production include bacterial wilt, powdery mildew, downy mildew, angular leaf spot, anthracnose and phytophthora blight. Gummy stem blight and belly rot are other disease possibilities for cucumbers. Cucumbers are also susceptible to viruses. Viruses that may infect cucumbers include the cucumber mosaic virus, zucchini yellow mosaic virus and watermelon mosaic virus. These diseases and viruses can cause cucumber yield reductions.
As a general rule, diseases present a more serious risk later in the growing season. Fruit and foliar diseases may also be less prevalent when the growing area has low humidity. Disease prevention strategies include adopting an appropriate crop rotation, choosing planting sites with suitable water and air drainage and selecting varieties with disease resistance. To maximize fungicide effectiveness, apply fungicides before disease pressure has escalated too much.
Harvest and Storage
Slicing cucumber size — both length and diameter — can dictate harvest timing. At 1.25- to 2-inch diameters and 6- to 8-inch lengths, slicing cucumbers are ready for harvest. Seeds should not have grown to full size or hardened, and the seed cavity should have a jellylike substance. Other attributes of market-ready fruit include a uniform dark green color, well-formed appearance, straight shape and medium size.
Typically, harvest begins 45 days to 60 days after cucumber planting. Plan to harvest a single cucumber growing area multiple times given staggered cucumber pollination. Harvesting cucumbers every other day is a good practice. Continuing to let fruit stay on the vine will cause quality to decline and yields to drop. When harvesting cucumbers, harvest workers should use their thumbs to push the stem from the cucumber fruit. Avoid pulling fruit from the vine because this may damage both the fruit and vine. Harvest workers should maintain good hygiene practices to prevent pathogen contamination. Other protocols throughout the production process should also stress food safety.
Cucumber producers may adopt several post-harvest practices. Field heat removal is one consideration. By removing field heat after harvest, cucumbers can experience prolonged shelf life, and they’re more likely to keep a desirable appearance. A forced air cooling system can quickly remove field heat. As another practice, producers commonly wash and grade cucumbers. Then, the cucumbers are waxed. During storage, shipping and marketing, waxed cucumbers may have less shrinkage and improved freshness.
When storing cucumbers, don’t allow the cucumbers to commingle with produce like ripe tomatoes and apples that release ethylene. The storage environment should have temperatures that range from 50 degrees F to 55 degrees F and 95 percent relative humidity. If exposed to storage temperatures cooler than 50 degrees F, then cucumbers could develop a chilling injury, characterized by water-soaked lesions, pitting and decay. Cucumber storage life typically doesn’t extend past 14 days.
Kaiser, Cheryl, Matt Ernst and Shawn Wright. 2014. Cucumber. University of Kentucky. Lexington, KY 40506.
Kelley, William Terry, ed. 2000. Commercial Production and Management of Squash and Cucumbers. University of Georgia. Athens, GA 30602.
Midwest Vegetable Production Guide for Commercial Growers. 2016. Midwest Vegetable Production Guide for Commercial Growers.
Motes, Jim, Warren Roberts, Jonathan Edelson, John Damicone and Jim Duthie. Slicing Cucumber Production. Oklahoma Cooperative Extension Service. Stillwater, OK 74074.
Orzolek, Michael, Lynn F. Kime, Steven M. Bogash and Jayson K. Harper. 2010. Cucumber Production. Penn State Extension. State College, PA 16801.
Reid, Judson and Amy Ivy. 2015. Best Management Practices in High Tunnel Production: Cucumbers. Cornell University Cooperative Extension. Ithaca, NY 14850.
Schultheis, Jonathan. 2000. Fresh Market Production Cucumbers. North Carolina Cooperative Extension. Raleigh, NC 27695-7602.
Suslow, Trevor V. and Marita Cantwell. 2013. Cucumber: Recommendations for Maintaining Postharvest Quality. University of California. Davis, CA 95616.