Cucumbers – July 2017 Plant of the Month
Grow cucumbers in your home or school garden and you’ll become part of a long gardening heritage. These crisp, refreshing vegetables originated in India, where they have been grown for the past 3000 years! Of course, many changes have come to this crop over the centuries, so gardeners can find a cucumber variety that works in just about any garden situation.
There's a type of cucumber for every use, including slicers for fresh eating, and varieties bred especially for pickle making. You can, however, pickle any small cucumber, or eat picklers fresh right off the vine, so experiment with different varieties, regardless of how you intend to use them. Slicers generally form 5- to 9-inch long, cylindrical cucumbers with tender, dark green skins and bear over a period of 4-6 weeks. Pickling varieties produce smaller fruits on fast-growing vines and generally produce most of their crop in the space of a couple of weeks. This concentrated bearing makes it convenient to harvest plenty for a pickling session. You can also grow round yellow cukes that look like lemons or ones that can reach up to 3 feet long!
Another choice is between hybrid and open-pollinated varieties of cucumbers. Open-pollinated types are old standbys and include the interesting ones with unusual colors and shapes. Hybrid cucumbers may bear more heavily and show greater resistance to some of the diseases that can trouble this crop.
Typically, cucumber vines produce separate male and female flowers on the same plant. Bees carry pollen from the male blossoms to the female blossoms in order for fruits to form. The term for these types of cucumbers is "monoecious."
But among the hybrids, you may see varieties labeled "gynoecious." These cukes only produce female flowers. Since every flower can produce a fruit, they bear especially big crops. In addition, these varieties have the broadest range of disease resistance. However, you do need to plant a monoecious variety that bears male flowers nearby in order to provide the pollen needed for fertilization. These types of cucumbers usually have some seeds of pollinator vines included right in the seed packet. Just be careful when you are thinning direct-sown seeds to leave some monoecious seedlings.
You may also encounter varieties labeled “parthenocarpic.” These types of cukes produce seedless fruits from flowers that don’t require fertilization. These varieties are popular for greenhouse growing because they will set fruits without pollinators present. However, seeded fruits can develop on parthenocarpic varieties if their flowers are visited by bees bearing pollen from seeded varieties growing nearby.
If you are short on space or planning to grow in containers, consider bush type cucumbers. These produce compact vines that begin bearing a little earlier than vining types, but the harvest will not be as large.
Site: Cucumber vines do best in well-drained soil that is rich in organic matter in a location that receives full sun. They can also be grown successfully in containers. Use at least a 5-gallon container with a minimum soil depth of at least 12 inches. Bush varieties are the easiest to grow in containers, but you can also grow vining types if you provide some kind of support.
When to plant: While its name may evoke the epitome of coolness, cucumber plants like it warm. Sow seeds directly in the garden when all danger of frost is past and the soil is at least 60 degrees F; 70 degrees is even better.
For a head start in short season areas, plants can be started indoors 3-4 weeks before your setting out date. Be sure not to start them indoors any earlier than this, however, as older plants don't tolerate transplanting well. Start seedlings in individual, plantable pots (like peat pots) to minimize root disturbance at planting time. Make sure transplants are well hardened off before they go out in the open garden. Transplant when the soil is warm, all danger of frost is past, and night temperatures stay reliably above 50 degrees F, generally about a week after the last spring frost date.
In many parts of the country you can plant more than one crop of cucumbers. Sow seeds every few weeks up until about 12 weeks before the fall frost date for the most bountiful harvest.
Planting: Although it is not absolutely necessary to support vines on some sort of trellis, if you do you'll get straighter, easier to pick fruits, save space, and have fewer disease problems to deal with. The vines cling by tendrils to supports. Tepees or vertical or A-frame trellises work well. Be sure to put the support in place before you plant your seeds. Bush varieties of cucumbers can be grown without supports.
Plant seeds in rows or hills, depending on how you plan to support the vines. Set seeds about ½ inch deep and 2 inches apart, thinning seedlings to 8-10 inches apart when plants have a several sets of leaves. When planting gynoecious varieties, include one monoecious plant for every seven or eight gynoecious plants for good pollination. Mulch to conserve soil moisture.
Care: Cukes are mostly water, and a consistent supply of water will give the best harvest. Moisture stressed cukes may be bitter and misshapen. Drip irrigation and mulch both help reduce the possibility of water stress. Feed vines growing in the ground with a balanced fertilizer about a month after planting. Container-grown plants will need regular fertilization throughout the season.
- Cucumber beetles: These small yellow-green beetles with either black spots or stripes on their backs begin feeding in early spring on the leaves and stems of cucumbers and related plants; a heavy infestation may totally destroy plants. The eggs they lay hatch into white grubs that can stunt plants by feeding on their roots. In addition to the direct damage they do, the beetles can spread bacterial wilt and mosaic virus, two diseases that can harm or even kill plants.
One of the best ways to control these pests is to rotate the location of cucumbers and their kin (squash, melons, pumpkins) in the garden and cover seedbeds or transplants with floating row covers immediately at planting time. You'll need to remove the covers when plants begin to bloom to allow bees in to pollinate, but covering helps to minimize damage to plants at the vulnerable seedling stage. Plants can be sprayed (or dipped, in the case of transplants) with a kaolin clay mixture. This natural product coats the leaves and repels beetle feeding. Combine with yellow sticky traps for additional non-chemical control. You might also consider a registered insecticide to control heavy infestations on uncovered plants.
- Misshapen fruits: These are the result of incomplete pollination, which causes portions of the fruits to develop improperly. This can happen if there is not enough bee activity when the plants are flowering; for example, if the weather is rainy when plants were blooming or if pesticide use has harmed pollinators. Spells of very hot weather (in the 90s) can also damage pollen and lead to poorly formed fruits. There's not much you can do about the weather other than wait it out. But you can protect the bees that visit your crops by minimizing pesticide usage; choosing pesticide products that are the least toxic to bees (check the label for this information); and applying pesticides in the evening when bees are not flying.
- Bitter tasting fruits: Many varieties of cucumbers naturally contain a bitter compound called cucurbitacin. When plants are stressed by things like heat, drought, low soil fertility, or disease they produce more of this compound, resulting in bitter cukes. Some of the newer, “burpless” varieties have been bred to have little or no cucurbitacin. Fruits harvested toward the end of the season from unhealthy plants are most likely to taste bitter. To reduce the likelihood of bitter cukes, keep plants consistently watered, use mulch to conserve soil moisture, and maintain soil fertility.
Cucumbers get big – often too big – fast, so pick frequently to keep vines bearing well. If you let overly mature fruits stay on the vine the plant will think its job is done and stop producing new fruits. Most slicing varieties taste best when they are between 6-8 inches long. Picklers are best harvested when they are 2-4 inches long.
- The world’s heaviest cucumber, to date, was grown in the U.K in 2015. It weighed a whopping 23 pounds, 7 ounces!
- The Roman emperor Tiberius demanded to be served a cucumber daily during his short reign. In order to put fresh cukes on his plate in wintertime the vines were grown in movable beds so they could receive the best sun exposure.
- Cucumbers are very low in calories, with only about 16 calories per cup. And while not stars in the nutrition department, they do offer modest amounts of potassium, Vitamin C, and fiber.