Vegetable · Cucurbitaceae
Cucumber
Cucumis sativus
Give it full sun, warm soil, and steady water, and a cucumber vine pumps out fruit faster than you can pick it.
Full sun
Every 2–4 days
59–95°F · 15–35°C
50–70 days
Overview
Cucumbers are a warm-season vine in the gourd family, the same clan as melons and squash, and they grow fast once the weather settles. Give the seed warm soil and full sun and a few plants will keep a kitchen in slicers all summer. Most run along the ground, but they climb a trellis just as well, which saves space and keeps the fruit clean.
There are two camps worth knowing. Slicing types grow long and smooth for fresh eating, while pickling types stay short and bumpy and turn out the best jars. A few newer varieties set fruit without any bees at all, which is handy under row covers or in a cool, wet season when pollinators are scarce.
They ask for little beyond warmth, sun, and even water. Let the soil swing from bone dry to soaked and you get bitter, misshapen fruit, so steady moisture does most of the work. Pick often, every day or two at the peak, and the vines keep setting more right up to the first frost.
Care
The short version: full sun, warm and fertile soil rich in organic matter, and steady moisture of about an inch a week, with frequent picking to keep the vines cranking out fruit.
Light
Cucumbers need full sun, at least six to eight hours a day, to fuel their fast growth and heavy fruiting. They'll limp along in partial sun, but you'll get fewer cucumbers and more disease where the leaves stay shaded and damp.
Water
Keep the soil evenly moist, around an inch of water a week from rain or the hose. Water deep at the base, and step it up while the plants are flowering and fruiting. Letting the soil dry out and then flooding it is the surest way to get bitter, crooked fruit.
Soil
Plant in fertile, well-drained loam loaded with organic matter, at a pH of 6.0 to 6.5. These vines love warmth, so a raised bed or a sheet of plastic mulch to heat the soil pays off early in the season.
Temperature
Cucumbers are a warm-season crop, happiest between 59°F and 95°F (15°C to 35°C). The seed won't even sprout in soil colder than 50°F (10°C), so there's no rushing them into a cold spring.
Humidity
Ordinary outdoor humidity suits them fine, so there's no level to aim for. Airflow matters more than moisture in the air, since crowded, damp leaves are exactly what powdery mildew wants.
Feeding
Work a balanced fertilizer such as 10-10-10 into the bed before planting. Once the vines start to run, give them a nitrogen side-dress to carry the plant through a long season of fruiting.
Pruning
Cucumbers need little pruning. On a trellis you can pinch back the side shoots to keep growth in hand, and you should pull off diseased or damaged leaves right away to slow any foliar disease from spreading.
Size & spacing
The vines stand only 8 to 18 inches (20 to 46 cm) tall but sprawl 3 to 8 feet (91 to 244 cm) wide along the ground. Give them that room to run, or a trellis to climb, so air moves through and the fruit stays off the soil.
When to plant
Cucumbers want heat and won't tolerate frost or cold soil. Wait until the danger of frost has passed and the ground has warmed to at least 60°F (16°C), usually mid to late May, then sow seed or set out transplants. From there you'll pick fruit from midsummer until the first frost closes the season.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: 2-4 weeks before the last frost (late April in northern regions); use peat or paper pots because seedlings resent root disturbance
- Plant: After all danger of frost when soil has warmed to at least 16-21°C (60-70°F), typically mid to late May; seeds will not germinate in soil below 10°C (50°F)
- Harvest: Flowers in early-to-mid summer; harvest fruit from midsummer until first frost, picking every 1-2 days to keep vines productive
Hardiness
USDA hardiness zones: 2–11
Temperature: down to -46°C
Troubleshooting
Most cucumber trouble turns up on the leaves or the fruit, and the cause is often heat, water, or a pest you can spot early. Match what you're seeing below and act before a small problem spreads down the vine.
Vines wilt in the day and whole stems collapse
This is usually bacterial wilt, spread by cucumber beetles that feed on the leaves and pass the bacteria into the plant. To confirm it, cut a wilted stem and press the cut ends together, then pull them apart slowly and watch for sticky strings of ooze. There's no cure, so pull and destroy any infected plant, and check stem bases for the frass and entry holes that point to a squash vine borer instead.
Fix:
- Remove and destroy infected plants; bacterial wilt cannot be cured
- Control cucumber beetles early in the season
- Use floating row covers on young plants, removing them at flowering for pollination
White powdery dust on the leaves that yellow and dry
This is powdery mildew, a fungus that settles in once you get warm days, cool nights, and crowded vines. It shows up first as patches on the older, shaded leaves and wipes off slightly under a finger. Cut out the worst leaves, open the planting up with wider spacing or a trellis, and keep cucumbers in full sun where the fungus struggles.
Fix:
- Remove heavily infected leaves
- Improve air circulation by spacing or trellising
- Apply a labeled fungicide at first sign if pressure is high
Fruit turns bitter near the stem end and skin
Bitterness comes from cucurbitacins, compounds the plant makes when heat or drought puts it under stress. The bitter taste collects in the skin and the stem end, so peeling the fruit and trimming that end removes most of it. To stop it before it starts, water steadily through hot spells, mulch to even out the soil, and grow a burpless or bitter-free variety.
Fix:
- Peel fruit and trim the stem end before eating
- Water consistently and mulch to even out soil moisture
Fruit comes out curled or pinched at one end
Crooked, pinched fruit points to poor pollination, often after cool, rainy weather keeps the bees away. Each cucumber needs many bee visits to fill out evenly, and a flower that gets too few sets a lopsided fruit. Pull the misshapen ones so the vine puts its energy elsewhere, skip insecticides while the plants are in flower, and plant some flowers nearby to draw pollinators in.
Fix:
- Remove misshapen fruit so the vine redirects energy
- Avoid spraying insecticides while plants are flowering
- Maintain even watering
Toxicity
Cucumbers are safe across the board. The fruit isn't toxic to people, pets, livestock, or birds, so a dropped slice in the garden is no cause for worry. The only thing to note is that the stems and leaves carry fine prickly hairs that can scratch sensitive skin at harvest.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
Cucumber is safe for cats, and many will nibble a slice with no trouble at all. The flesh is mostly water, so offer it in small pieces as a light treat.
Dogs None
Dogs can eat cucumber without any risk, and the crunchy, low-calorie slices make a good snack. Cut it into bite-sized pieces so a fast eater doesn't gulp a whole chunk.
Horses Safe
Horses tolerate cucumber well, and a few sliced pieces make a refreshing summer treat. Stick to small amounts alongside their normal forage.
Rabbits Safe
Rabbits can have cucumber in moderation, though it carries little fiber and lots of water. A thin slice or two now and then is plenty next to their hay.
Livestock Safe
Cattle, goats, and sheep can eat cucumbers and the trimmed vines safely. Introduce surplus fruit gradually so a sudden pile doesn't upset their digestion.
Birds Safe
Both pet birds and backyard hens peck happily at cucumber, flesh and seeds alike. It's a hydrating snack to share, with no part of the plant off limits.
People Safe
Cucumber is a kitchen staple eaten raw, pickled, or sliced into salads, and every part of the fruit is safe. The skin and stem end of a stressed fruit can taste bitter, but that's flavor, not danger.
Stems and leaves bear slightly prickly hairs that can irritate sensitive skin; gloves are optional when harvesting spiny-fruited varieties.
Varieties
Cucumbers split mainly into slicers and picklers, with a few compact and seedless types worth knowing. These are the names you'll run across most.
Marketmore 76
A classic slicing cucumber that holds up well thanks to its strong resistance to scab and cucumber mosaic virus.
Straight Eight
An heirloom slicer that produces straight, dark green fruit about 8 inches long.
Boston Pickling
A productive heirloom pickling type that bears short, blocky fruit with bumpy skin.
Spacemaster
A compact bush type that fits well in small gardens and containers.
Diva
A parthenocarpic, seedless variety that sets fruit without pollination and has thin, non-bitter skin.
Companions
Cucumbers do well beside beans, corn, and quick radishes, and poorly next to potatoes or strongly aromatic sage that extension guides flag as bad neighbors.
Plant near
beans: Extension companion-planting guides list beans as a traditional cucumber companion; legumes fix nitrogen that benefits neighboring crops.
corn: Listed as a compatible companion in extension guides; tall corn can also serve as a windbreak and partial support.
radish: Traditional extension-listed companion; quick-maturing radishes use space efficiently between young cucumber plants.
How to propagate
Cucumbers grow easily from seed, and that's nearly the only way gardeners start them. The trick is warm soil and as little root disturbance as possible.
SeedEasy
Direct sow after the last frost once soil reaches at least 16°C (60°F), or start indoors 2-4 weeks before transplanting · Seeds germinate in 3-10 days in warm soil; transplants establish within 1-2 weeks
Most gardeners grow cucumbers straight from seed, which is the easy and reliable route. Direct sow once the last frost has passed and the soil has warmed to at least 60°F (16°C), planting 0.5 to 1 inch (1.5 to 2.5 cm) deep in hills or rows, and the seeds break ground in 3 to 10 days. If you want a head start, sow indoors 2 to 4 weeks before transplanting, but use peat or paper pots, since the roots resent being disturbed and transplants need a week or two to settle in.
Myths
Cucumbers planted near melons or squash will cross-pollinate and ruin the flavor.
Cucumbers can't cross with melons or squash, since they are separate species, so a neighboring crop has no say in how your cucumbers taste. Off-flavors trace back to cucurbitacins the plant makes under heat and drought stress. Even cross-pollination between cucumber varieties only changes the seeds, never this season's fruit.
A bitter cucumber is spoiled and dangerous to eat.
The bitterness is just cucurbitacins built up in the skin and stem end of a stressed fruit, not a sign of spoilage. Peel the cucumber and trim that stem end and most of the bitter taste goes with it.