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Cucumber

Planting

Cucumber (Cucumis sativus) is a warm-season vegetable that grows best at temperatures between 75 and 85 °F. Cucumbers are very tender and can be killed by light frosts. Start cucumbers in the garden by planting seed or transplants.

Cucumber (Cucumis sativus) is a warm-season vegetable that grows best at temperatures between 75 and 85 °F.

Cucumber (Cucumis sativus) is a warm-season vegetable that grows best at temperatures between 75 and 85 °F.
Barbara H. Smith, ©HGIC 2018, Clemson Extension

Plant seed or transplants after the fear of frost has passed, and the soil temperature has reached 70 °F. Seeds will not germinate at soil temperatures below 50 °F. Seeds may be started indoors two to three weeks prior to planting outdoors.  Spring and fall crops may be grown.

Planting Dates

Area Spring Summer
Piedmont Apr.15-May 15 July 1-15
Central Apr. 1-15 Aug. 1-10
Coastal Mar. 20-30 Aug. 1-20

For non-trellised cucumbers, space plants 8 to 10 inches apart in rows that are 5 feet apart. If cucumbers are trellised, plant four to five seeds per foot in rows spaced 3 feet apart. When plants are 4 to 5 inches high, thin so they are 9 to 12 inches apart.

If non-trellised, space cucumber plants 8 to 10 inches apart in rows that are 5 feet apart.

If non-trellised, space cucumber plants 8 to 10 inches apart in rows that are 5 feet apart.
Barbara H. Smith, ©HGIC 2018, Clemson Extension

Cultivar Types

Cucumbers are typically divided into two groups: pickling and slicing.  Pickling cucumbers are used to make pickles, but may also be eaten raw. They produce shorter, blockier fruit with bumpy skin.  Slicing types are typically eaten raw, have softer flesh, thicker skin, and are long and slender. Bush varieties produce well in a limited amount of space and are a good alternative in the garden when trellising is not possible.

Most cultivars produce female and male flowers and require pollinating insects to produce fruit. Female flowers are produced singularly, with a swollen base (the ovary) where the fruit develops and a spiral-shaped stigma (the top of the pistil that receives the pollen). Male flowers are produced in clusters on long narrow stems and have 3 stamens that produce the pollen. New hybrid parthenocarpic (produce mostly or all female flowers and do not require pollination) cultivars are being bred to bear fruit earlier with a seedless fruit set and better yield. This is because they have either a greater proportion of female flowers or possess only female flowers. These newer hybrids do not require insects for pollination.

Female flowers are produced singularly, with a swollen base (the ovary) where the fruit develops.

Female flowers are produced singularly, with a swollen base (the ovary) where the fruit develops.
Justin Ballew, 2018, Clemson Extension

Cultivars

The following cultivars are selections that are often planted in vegetable gardens, but there is a wide selection of newer cultivars being introduced each year. It is recommended that homeowners try multiple cultivars to determine which ones yield and taste better, and have a better disease and insect tolerance in their garden. If there is a problem with misshapen fruit due to poor pollination, plant parthenocarpic cultivars, such as Diva, Excelsior, Sugar Crunch, or SV4719CS. These hybrid, burpless or European-type cucumbers will produce long, seedless cucumbers without bees and other pollinating insects.

  • Picklers – Fancipak (hybrid), Calypso, Carolina, County Fair, Homemade Pickles, Max Pack (hybrid), Excelsior (hybrid), Regal, and Sumter.
  • Slicers – Salad Bush (hybrid), Straight Eight, Sweet Slice, Sweet Success (hybrid), Burpless (hybrid), Diva (hybrid), Sugar Crunch (hybrid), SV4719CS (hybrid), and Poinsett 76

Pickling cucumbers are used to make pickles, are shorter, and have bumpy skin.

Pickling cucumbers are used to make pickles, are shorter, and have bumpy skin.
Barbara H. Smith, ©2018 HGIC, Clemson Extension

Slicing cucumbers are typically eaten raw, have a smooth skin, soft flesh, and are long and slender.

Slicing cucumbers are typically eaten raw, have a smooth skin, soft flesh, and are long and slender.
Barbara H. Smith, ©2018 HGIC, Clemson Extension

Soil

Cucumbers grow best in a well-drained sandy loam to clay loam soil enriched with up to 20% organic matter. A slightly raised bed will aid in drainage and may help control certain diseases. The soil pH should be between 6.0 and 6.5.

Fertilizing

Cucumbers require moderate amounts of fertilizer. A soil test is always the best method for determining the fertilization needs of the crop. For more information on soil testing, see HGIC 1652, Soil Testing.

Follow the results of a soil test to maintain a soil pH between 6.0 and 6.5 and optimal fertility levels. If a recent soil test has not been taken, make a preplant application of 5-10-10 at the rate of 3 pounds per 100 square feet. This initial preplant application will normally supply all of the phosphorus and potash needed by most garden vegetables. In the coastal areas of South Carolina, there may be sufficient levels of phosphorous present, a preplant application of 15-0-15 should be used. Before the vines start to develop, sidedress with 34-0-0 at 1 pound per 100 feet of row or calcium nitrate (15.5-0-0) at 2 pounds per 100 feet of row. More frequent sidedressing may be required if the garden is sandy or if leaching rains occur. Do not overfertilize with nitrogen as this encourages excess vine growth and reduces fruit production. Apply fertilizer along one side of the row and about 4 to 6 inches from the plants depending on their size.

Watering

Cucumbers have a shallow root system and can suffer when no irrigation is provided during droughts. Practice good cultivation and provide adequate water to moisten the soil to at least a 6 inch depth. It is important to provide a uniform moisture supply to the crop as this is critical during fruit set and development. To aid in preventing disease, water at the base of the plant in the morning and avoid wetting the foliage.

Mulching helps provide uniform moisture, conserves water, and reduces weeds. Spring-planted cucumbers can be harvested earlier if mulched with soil-warming black plastic. Organic materials, such as pine straw or bark mulch, are useful in the summer to keep the fruit clean in non-trellised plantings.

Cultural Practices

Most varieties of cucumber vines spread from row to row. Training on a trellis or fence will lift the vines and fruit off of the soil, freeing up space in the garden, keeping the fruit clean, reducing disease, and making harvest easier. A satisfactory trellis is one that is about 6 feet high with top and bottom wires and plastic twine tied between the two wires at each plant. Posts should be no more than 15 feet apart and the top wire must be tight.

Harvesting & Storage

Depending on the cultivar, cucumbers should be ready for harvest in about 50 to 70 days. Pick as frequently as necessary to avoid oversized fruit. By keeping the fruit picked, the vines will continue to produce. Begin harvesting when cucumbers are about 2 inches long up to any size, but before their flesh becomes bitter, seeds harden or skins begin to yellow.  Pickling types should be harvested between 2 and 6 inches in length, while slicing and burpless types are typically picked between 6 and 10 inches long. Harvest the fruits by cutting stems with a sharp knife or pruners.  This prevents vine damage and results in a clean break. Store cucumbers in the refrigerator for about a week. The optimal conditions for storage are temperatures of 45 to 50 °F and 95% relative humidity.

Problems

Misshapen fruit is often due to low fertility or poor pollination.

A properly pollinated cucumber is on the left. The three misshapen cucumbers on the right are due to low fertility or poor pollination.

A properly pollinated cucumber is on the left. The three misshapen cucumbers on the right are due to low fertility or poor pollination.
Justin Ballew, ©2018, Clemson Extension

Failure to set fruit can be caused by too few bees or other beneficial insects for adequate pollination or changes in temperature. To ensure better pollination, plant a diverse array of flowers in and around the garden to keep pollinating insects visiting year round. Fruit is only produced when insects carry pollen to a female cucumber flower, and pollinating insects are essential for this purpose. Also, the first 10 to 20 flowers on a plant are male and will not produce fruit. Hand pollination can improve cucumber fruit production in the absence of pollinators. Flowers open for one day only and shrivel by the afternoon; therefore, it is best to hand pollinate in the morning. Pick a male flower, remove the petals, and leave the pollen-covered anthers. Rub the pollen from the anthers onto the stigma of female flowers. This will enable sufficient transfer of pollen to produce well-shaped fruit.

Bitterness can be due to temperature variations of more than 20 °F and storage of cucumbers near other ripening vegetables. Some cucumber cultivars have the tendency to become bitter; therefore, plant cultivars, such as Diva, that are less prone to bitterness. Bitterness will occur more toward the stem end where the cucumber attached to the vine. By cutting off the stem end and peeling the cucumber, the bitterness will be reduced.

The major pests that feed on cucumber are cucumber beetles, pickleworms, aphids, mites, whiteflies, and squash vine borers.

Diseases that occur in the home garden include powdery and downy mildews, anthracnose, gummy stem blight, bacterial wilt, mosaic viruses, target spot, and belly rot. Most of these diseases are not a problem in the spring except for bacterial wilt.  Powdery mildew can occur anytime humidity is high and the temperatures are cool. Downy mildew along with the other diseases tend to also be problematic from midsummer to fall. To reduce the chance of disease, avoid overhead irrigation which raises the level of relative humidity within the plant canopy.

Powdery mildew can occur anytime humidity is high and the temperatures are cool.

Powdery mildew can occur anytime humidity is high and the temperatures are cool.
Justin Ballew, ©2018, Clemson Extension

More information on controlling cucurbit diseases and insect pests is available in HGIC 2206, Cucumber, Squash, Melon & Other Cucurbit Diseases; and HGIC 2207, Cucumber, Squash, Melon & Other Cucurbit Insect Pests.

If this document didn’t answer your questions, please contact HGIC at hgic@clemson.edu or 1-888-656-9988.

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