Cucumbers are, to me, a quintessential summer vegetable. (To paraphrase British humorist Miles Kington: Knowledge is knowing a cucumber is a fruit; wisdom is not putting it in a fruit salad.) The flesh of a cucumber is cool and crisp, with endless culinary uses: paired with yogurt in raita or a sauce for falafel, in Greek salads with feta, as an ingredient in gazpacho, and even as a garnish for gin and tonics. And pickling needn’t be a hassle: refrigerator pickles are delicious and keep for weeks.
Varieties
Cucumbers are usually categorized as “slicing” or “pickling.” Slicing cucumbers are longer, with thicker skins. Pickling cukes typically fruit earlier, with a short fruiting period (7-10 days), while slicing varieties can fruit for 4-6 weeks.
Cucumber plants form either bushes or vines. Bush varieties are more compact, fruit earlier, and bear less fruit than vining types. As discussed below, vining cucumbers grow well on trellises.
English – sometimes called European – cucumbers exhibit parthenocarpy, that is, they can set fruit without pollination. These varieties perform well in greenhouses, where pollination might be inefficient. Some growers prefer English varieties because the cucumbers are effectively seedless – but with an important caveat: if the flowers do happen to be pollinated, the resulting cucumbers will have seeds.
Asian cucumbers are usually longer, thinner skinned, and have a milder taste than North American varieties. The cucumbers will be straighter – and look spectacular – when grown on trellises. Whereas Western cucumbers belong to the species Cucumis sativa, some Asian cucumbers are from the Cucumis melo group, the same species as honeydew and cantaloupe. Cucumbers from this species often have slightly sweet flesh. Armenian cucumbers also belong to Cucumis melo, and are notable for their pale skin and deeply scalloped edges.
Bed Prep
Cucumbers grow best in soil with plenty of organic matter. When starting a new garden, incorporate 4-6 inches of compost into the top foot of soil with a rototiller or by double-digging. For existing beds, spread an inch or two of compost on the surface and loosen the soil with a broadfork or spading fork to bring the compost down into the soil. We recommend no-till methods in established garden beds to promote healthy soil structure.
Recommended soil pH is 5.5-7, slightly acidic to neutral. Cucumbers are heavy feeders, so soil nutrients should be fairly high. A soil test is a good idea to ensure that pH and nutrients are in the right ranges. Test kits can be picked up at the Virginia Cooperative Extension office in the Albemarle County Office Building, 460 Stagecoach Road in Charlottesville. Soil test results come with amendment recommendations; contact our horticultural help desks for help interpreting these recommendations. If the soil hasn’t been tested recently, apply 3 lbs. of 5-10-10 per 100 square feet.
Cucumbers need plenty of sunshine, so plant them in a location with at least 8 hours of direct sun.
Starting
- Outdoors Cucumbers like it hot. Wait to sow directly until all danger of frost is gone and soil temperature is at least 65℉. Plant 3-4 seeds a few inches apart in a low mound, water thoroughly, and keep the soil moist – especially if your soil tends to crust over. Thin to 2-3 plants after germination. Cut the extra plants at their base, to avoid disturbing the roots of the remaining plants.
- Indoors Sow seeds indoors 3-4 weeks before transplanting. Harden seedlings off. Transplant only after the soil has warmed to 65℉. Transplant carefully so the roots aren’t damaged.
- Succession planting To extend the harvest, sow some seeds a few weeks later, in late June or early July.
Trellising
Vining varieties will thrive on a trellis. Some advantages include: reduced space requirements, straighter fruit, better air circulation, faster drying, and fewer diseases, and (creak) easier harvesting.
Trellises should be 5-6 feet tall. There are many options for materials. Twine works well, in particular because the vines’ tendrils can grab the rough material. Cattle panels, i.e. heavy wire fencing, are another good choice. Netting is convenient but needs to be supported from above. I’ve often found the material to be slippery, so use plastic tomato clips to attach vines to netting if necessary.
Plant Care
Cucumbers have a shallow root system and need plenty of water. Keep the top 6 inches of soil moist. Irrigate regularly if there hasn’t been much rain; in other words, don’t let the soil dry out. Consistent soil moisture will prevent blossom end rot.
Side-dress with a nitrogen-only fertilizer (1 lb. of 34-0-0 per 100 square feet) after a few weeks, when vines begin to form. Don’t over-fertilize with nitrogen or you’ll have too many leaves and not enough flowers.
Pollination
Uneven or curled fruit (see picture) are usually the result of incomplete pollination. Cucumbers have separate male and female flowers (see picture). This means that insects – or humans – must spread pollen from male to female flowers.
For efficient pollination, ensure there are plenty of pollinators around. One method is to create a pollinator garden with flowering plants that attract pollinators. Another is to eschew insecticides, or at least stop applying them once plants start blooming. Even organic pesticides can harm pollinators.
Diseases
Cucumbers are extremely susceptible to fungal diseases – in my experience at least. Downy mildew and powdery mildew (see picture) are among the most common. Prevention is the best way to control disease, as most plant diseases are difficult if not impossible to cure. Begin by choosing disease-resistant cultivars. Cornell University has compiled a list of disease-resistant cucumber varieties (and similar lists for other crops).
Next, use cultural practices to prevent diseases from getting established. Trellising will help keep leaves dry and reduce fungal growth. Avoid overcrowding: thin to 2 or 3 plants per mound, and separate mounds by 3 feet. Water at the base of plants and try not to splash soil up onto the leaves. Mulch will reduce soil splashing and the need for irrigation. Control insects (see below) that spread diseases like bacterial wilt or viruses (see pictures). At the end of the season, remove all plant litter.[symple_column size=”one-half” position=”first” fade_in=”false”]
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[/symple_column]Check often for symptoms of disease. When you notice diseased plants, particularly plants with insect-borne diseases, immediately remove and discard – don’t compost – the diseased plants. For fungal diseases, you might get away with removing affected leaves if you catch the infection early.
The Virginia Cooperative Extension’s Pest Management Guide (Table 2.4) lists sprays – including organic options like neem oil and copper – that may slow progression of fungal diseases. (Always follow label instructions and use personal protective gear when applying pesticides.) Succession planting is a better option: new plants will be ready when older plants – inevitably, in my experience – succumb.
Insects
Cucumber beetles, both spotted and striped (see pictures), are problems because they both directly damage plants and transmit bacterial wilt. To avoid cucumber beetles, don’t plant cucumbers where any cucurbit – cukes, squash, melons – has grown the past two seasons. Delay planting of all cucurbits until June 15th: adults overwinter in soil and emerge in spring to lay eggs, but larvae will die if their host isn’t present. Row covers will protect young plants, but must be removed after flowering to allow pollination. Scrupulously remove plant material at the end of the season to reduce the overwintering beetle population.[symple_column size=”one-half” position=”first” fade_in=”false”]
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Aphids bear live young, so severe infestations (see picture) can appear seemingly out of nowhere. They feed by sucking liquids out of plant tissue, thereby both directly damaging plants and spreading diseases. The symptoms of aphid infestations are shriveled or curled leaves. The aphids themselves are easy to see: they’ll look like gray or yellow-green dust covering leaves and stems. Knock aphids off plants with a strong stream of water from a hose (but not a power-washer).
Chapter 2 of the Pest Management Guide lists chemical controls, conventional and organic, for cucumber beetles, aphids, and other pests. Only use these for severe infestations. (Always follow label instructions and use personal protective gear when applying pesticides.) To avoid harming pollinators, don’t apply insecticides after plants have bloomed. Carefully monitor plants to catch infestations early in the season.
Closing thoughts
Cucumbers are infamous for overproduction, but in my opinion too much of a good thing is wonderful. Your neighbors will always be happy to accept gifts of summer produce, and local food banks may accept donations of fresh produce.
References and further reading
Featured image: Gerald Holmes, Strawberry Center, Cal Poly San Luis Obispo, Bugwood.org; CC BY-NC 3.0 (cropped)
Climbing Cucumbers University of Maryland Extension
Cucumber Clemson Cooperative Extension
Cucumbers Cornell Cooperative Extension
Cucumbers, Melons, and Squash Virginia Cooperative Extension
Disease-resistant Cucumber Varieties Cornell College of Agriculture and Life Sciences
Growing Cucumbers in a Home Garden University of Maryland Extension
Growing Cucumbers in the Home Garden University of Georgia Extension
Hand Pollination of Squash and Corn in Small Gardens University of Florida Extension
Hardening Off Vegetable Seedlings for the Home Garden University of Maryland Extension
Insect Management on Cucurbit Vegetables NC State Extension
Integrated Pest Management and Pesticide Safety Virginia Cooperative Extension
Key to Common Problems of Cucumbers University of Maryland Extension
No-till in the Home Garden: Why and How Ralph Morini, Piedmont Master Gardeners
Organic-approved Pesticides: Minimizing Risks to Bees (PDF) The Xerces Society for Invertebrate Conservation
Pest Management Guide (2024) Virginia Cooperative Extension
Plant a Pollinator Paradise Deborah Harriman, Piedmont Master Gardeners
Pollination Problems of Vegetables University of Maryland Extension
Starting Seeds Indoors Cleve Campbell, Piedmont Master Gardeners
Vertical Gardening Using Trellises, Cages, and Stakes Virginia Cooperative Extension
