Planting
The growth period of greenhouse cucumbers lasts from 55-60 days. The primary method for cucumber planting is direct seeding in rows spaced 3-4 feet wide, with 4-8 inches between plants in the row. The seed depth should be 1-11 ½ inches. Close proximity of plants will increase the yield, reduce weed growth, and keep the maturity rate uniform.
Cucumbers are sensitive to growing conditions. Favorable growing conditions for a cucumber are similar to that of semitropical plants; humidity, high temperatures, intensity of light, and constant water and nutrient supply are all necessary. Under these conditions, and with proper pest management, the plants have an opportunity to grow fast and produce heavy yield. Maintaining a canopy that allows the maximum amount of light and air to the plant will create maximum yields. This involves frequent pruning of the stems, laterals, and tendrils, as well as vertical wire training. When the plant produces too much fruit, it can cause the plant to become exhausted and abort future fruit.
Air temperature impacts vegetative growth, flower initiation, fruit development and quality. Optimum growing night temperatures range from 66.2-68 degrees Fahrenheit and optimum day temperatures range from 68-71.6 degrees Fahrenheit.
Regulation of greenhouse conditions is important to maximize yield. A disadvantage with high relative humidity is that diseases can develop and there is an increased chance that water condensation could occur on the plants. With low relative humidity, the conditions favor formation of powdery mildew and allow spider mites to reside. The irrigation system is a critical component because large amounts of water must be provided to the growing medium without flooding its roots and depriving them of oxygen.
The trellis saves space and is used to increase air circulation, helping to decrease risk of disease; it also serves as a way to protect the cucumber from developing damage due to moisture from lying on the ground.
Cucumbers grown in Florida have a long harvest season when field grown.In North Florida, field-grown cucumbers are planted from February to April and August to September. In Central Florida, the planting season is from January to March and September for the fall season. For the Southern region of Florida, planting can commence anytime from September to April.Greenhouse production in Florida is usually done September through June. Planting in greenhouses in summer months is avoided due to high heat and humidity, which reduces the plant’s production.
The type of soils used in growing cucumbers varies. Some acidic soils can be used, but they require liming and fertilization before the seeds are planted. Cucumbers grow best in slightly acidic soils with a pH range of 5.8-6.5.The soil should be properly prepared before field planting begins. Common steps include soil fumigation, black plastic mulching, applying fertilizer during bed preparation, using foil or other reflective mulches for repelling aphids, and applying direct seeding throughout the mulch. Cucumber seedlings develop faster in higher temperatures, but cucumber growth is improved when soil temperatures are cooler.
Nearly all greenhouse production of cucumbers in Florida uses bag culture and perlite as the medium. Rockwell may also be used as a medium. Greenhouse cucumbers do best in soil with a pH range of 5.5-7.5, but, specifically for mineral soils, the pH range must be from 6.0-6.5. As for organic soils in greenhouse production, the optimum pH level must range from 5.0-5.5.
Different varieties of cucumbers are able to cross pollinate with each other. A pollen grain is needed for each seed within each cucumber. Without proper pollination, the fruit could be aborted, disfigured, or be a poor fruit set (transition of an ovary to a young fruit). Proper pollination hives should be brought to the field when 25% of the plants in the field have flowered. A single flower needs to be visited by bees 10-20 times to be pollinated. If the bees are brought into the fields before 25% of the plants have flowered the bees could be attracted to other food sources such as wildflowers, thereby reducing yield. When bringing hives to the fields the weather should not be cool or wet, as these conditions are unfavorable for bees, and this causes the bees to be less active and the outcome is poor fruit sets.
Soil and Amendments
Cucumbers are well grown in muck soil, but can be produced in sandy soils as well, which requires less cleaning before marketing.
In cucumber production, soil amendments are used for improvement of soil quality. Composted green waste or manure can be added to soils before planting begins, which helps to increase the holding capacity for water and supply nutrients to the crop. Farmers must be careful where they purchase the manure from sinceE. coliis a known contaminant; it is best to look into commercially composted manure. Soil mulches are commonly used to modify soil properties such as temperature, weed control, conserving water, protecting fruit from insects, soil moisture, and to control erosion.There are nutrients that farmers may choose to use during the process of producing cucumbers. The primary nutrients used are nitrogen, potassium, phosphate and the secondary nutrients are considered magnesium, calcium, and sulfur.For cucumbers that are grown on mulch that are polyethylene free, reductions of up to one half of the nitrogen and potassium fertilizer are applied at planting.
Irrigation
Many irrigation systems work well for cucumber production. The type of irrigation system that is used is based on natural resources and cost benefits. Drip, sprinkler, and surface are types of irrigation systems used with mulched production.Drip irrigation uses a variety of plastic pipes to carry a low flow of water under low pressure to plants. The low volume application of water to plant roots allows for a balance of air and water in the soil, providing plants with better growth.Sprinkler irrigation systems are different from the other systems because they apply water through the air versus directly in the soil. The water can be distributed through a pipe or sprinkler head and is sprayed into the air and falls on the ground similar to rainfall.Surface irrigation systems distribute water by gravity flow of water going over the soils’ surface. As this occurs the soil stores the water and the system acts as a medium spreading and infiltrating the water. Some greenhouse cucumbers are irrigated using a closed irrigation technique called a drain-to-waste irrigation system.
Common sources of water for irrigation are ground, surface, or potable waters. The water’s pH is important in an irrigation system, the recommended optimum pH of the nutrient (nitric, sulfuric, and phosphoric acid) solution that is applied to the plants through the irrigation system should range in between 5.5-6.0. These conditions vary if the water has a high bicarbonate concentration, which prevents precipitation when fertilizer salts are added.
Salinity, perchlorate, chloride, and glyphosate toxicity can all negatively affect cucumbers during their growing process. Salinity can cause plant growth to be stunted and cause leaves to have a dull, dark green color with a narrow band of yellow necrotic tissue around leaves prone to wilting. Studies have demonstrated that with an increase of salt in the water there is a decrease in cucumber yield. Chloride, when added to water used in the irrigation system, showed a reduction in plant vigor and produced a light green tissue band around the leaves margins, along with necrosis and edge scorching. These leaves are at risk for a reduction in photosynthesis activity and premature leaf abscission. Perchlorate is a strong acid and is available in mineral deposits of natural nitrates. Due to its strong chemical properties it decreases the Ribulose Diphosphate Carboxylase (RuDP) enzyme activity used for cultivation in greenhouse vegetables. The symptoms of exposure to high concentrations of perchlorate include female flowers beginning to open, leaves curling with partial necrosis, and a reduction in fruit sets, which in turn reduces yields.
Pests & Insecticides
Pesticides are used in the cucumber production process to help decrease the impact of insects on the plant. There is a range of insects that can attack cucumbers, but the major insects that are prominent in Florida are the pickleworm, melonworm, and silverleaf whitefly.In cucumber greenhouse production, the most common pest is the whitefly. Other insects that impact production outside of greenhouse are arthropods such as melon thrips, leafminers, banded cucumber beetle, flea beetles, mites, stink bugs, wireworms, grasshoppers, leafhoppers, squash bug, squash vine borer, and loopers. These pests pose a serious concern for the grower, as cucumber crops have a very low tolerance for insect damage. The cucumber beetle is comprised of six different species across the United States. Three of these beetles are found in Florida. The banded cucumber beetle is located in the southern part of Florida. The spotted cucumber beetle and striped beetle are found in North Florida.
The cucumber beetle’s larvae eat away at the plant from the roots to the stems.As an adult, they eat away at the stems that are below the plastic mulch, as well as the leaves and the fruit. The crop is damaged quickly by feeding on the cotyledons first and then moving to foliage. Crop damage from these beetles often transmitsErwiniatracheiphila, which is the causal agent of bacterial wilt.The squash mosaic virus can also be transmitted and there can be an increase of incidence of powdery mildew, black rot, and fusarium wilt.
Insecticides are typically used to combat bacterial wilt.As for the squash mosaic virus, which is transmitted by insects, once the plant is infected it must be removed so that it does not infect the other plants. Preventative measures, such as weed control, can be taken to try to avoid the occurrence of the virus.
In 2000, Florida growers applied insecticides totaling 15,500 pounds of active ingredient to 97 percent of the state’s fresh-market cucumber acreage. Annually, between 94-97 percent of fresh market cucumber acreage has been treated with insecticides; the most commonly applied insecticides in Florida on fresh-market cucumbers are Bacillus Thuringiensis, Methomyl (Lannate®), and Endosulfan, a cyclodiene chlorinated hydrocarbon insecticide.
Disease Prevention
There are a few techniques that are used to help lessen the chance of the cucumber encountering disease. Commercial growers can utilize certified disease-free seeds and keep the garden and surrounding area free of weeds that harbor insects that can spread viruses and bacterial wilt. Once harvesting is complete, growers should remove the plant debris that is left behind in the garden because some diseases have the ability to survive on plant debris.An important measure in controlling disease is host resistance. The types of diseases that can affect cucumbers are gummy stem blight, which is a leaf disease caused by the fungusDidymella bryoniae,Anthracnose caused by the fungusColletotrichum obiculare,Fusarium wilt caused by the fungusFusarium oxysporum,and downy mildew (favored in moist conditions) caused by the fungusPseudoperonospora cubensis.
Glyphosphate is an herbicide that, even in small amounts, if absorbed by the cucumber will cause damage such as turning the color of the leaves from light green to a yellow, stunting the growth, and causing upward curling.
Fungicides are most useful when they are applied prior to infection and must be reapplied once the infection occurs every five to seven days. Some examples of the types of fungicides used are Previcur Flex, Gavel, Tanos, and Ranman.
Harvesting, Packaging, and Storage
The harvesting process can be done by hand or machine and is different depending on the cucumber. The following videos will show different harvesting techniques used in growing cucumbers.
Greenhouse Cucumbers:
Harvesting Machines:
Cucumbers should be picked when they are crisp, green, and tender; large fruits should be removed from the vine so that new fruits are encouraged to grow.Slicing cucumbers are hand-harvested at a range of 6–10 inches long and 1.5–2.5 inches in diameter. They usually are picked over a three-week time frame, six to eight times. Pickling cucumbers are generally harvested five to six times, in three to four intervals to avoid oversizing. Gherkin cucumbers are harvested daily or every other day based on the weather and the stage of growth.
Fresh-market cucumbers and European types are hand-harvested and placed in plastic bins to be transported to the packing house. Once the cucumbers have reached the packing house, they are washed, sorted, and graded. Since the fresh-market cucumbers are prone to extreme dryness, they are waxed prior to being packed to help reduce water loss and skin injury. As for greenhouse cucumbers, most are shrink-wrapped with polyethylene films.
Cucumbers should not be stored with produce that generate ethylene, such as apples and tomatoes. The ethylene in these types of produce causes the cucumber to yellow rapidly from the loss of chlorophyll. For the best postharvest results, including a long shelf life, cucumbers should be stored at a temperature ranging from 44.6–50 degrees Fahrenheit and 85–95% relative humidity in air, 46.4–53.6 degrees Fahrenheit in 1–4% oxygen and 50–54.5 degrees Fahrenheit in 0% carbon dioxide.
Some cucumbers are harvested for pickling. There are three general methods used to ferment cucumbers for pickling. One way is by ‘salt shock’, in which cucumbers are preserved in 5–8% sodium chloride until the fermented sugars are converted to acids, increasing the salt concentration along the process. The second method is known as the ‘genuine dill’. With this method, the cucumber is fermented in 45% sodium chloride, flavor is added, then the cucumber is sold as is. The ‘overnight dill’ is the third method, which is performed by fermenting cucumbers in 2–4% sodium chloride containing dill weed and garlic; the fermentation continues until it reaches the desired acidity. The pickled cucumbers are then refrigerated.
For more information on cucumber production, please visit theProduce Point of Origin Database.
