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Cucumber

Cucumis sativus

VegetableViningSummer Easy

Crisp and thirsty, cucumbers race up a trellis in summer heat. The first flowers are all male, so early flower drop is normal — keep them evenly watered to avoid bitter fruit.

Growing conditions

Light
Full sun — at least 6–8 hours of direct sun per day
Water
High
Soil
Fertile, well-drained loam rich in organic matter; warms quickly in spring · pH 6.0–6.8 (tolerates up to ~7.0)
When to sow
1–2 weeks after your average last spring frost, when nights stay above ~10°C (50°F). For a fall crop in long-season zones, succession sow every 2–3 weeks up to ~12 weeks before your first fall frost.
Spacing
30–45 cm (12–18 in) apart in rows ~1.2 m (48 in) apart, or 2–3 plants per hill 90 cm (36 in) apart; on a trellis, 20–30 cm (8–12 in) apart
Days to maturity
50–70 days from direct sowing (most slicers 55–65)
Hardiness
Grown as a summer annual in all zones (roughly USDA 3–11); not winter-hardy anywhere — timing, not zone, is what matters

How to grow it

  1. 1

    Sow into warm soil

    Wait until soil is at least 16°C (60°F) and frost is past, then sow seeds 2–2.5 cm (0.75–1 in) deep. Seeds fast in warm ground but rot in cold, wet soil, so patience beats an early start. Pre-warm beds with black plastic in cool zones.

  2. 2

    Thin and give them room

    Once seedlings have a couple of true leaves, thin to the strongest plant every 30–45 cm (12–18 in), or 2–3 plants per hill. Crowding traps humid air and invites mildew.

  3. 3

    Trellis or stake the vines

    Train vines up a sturdy 1.8 m (6 ft) trellis or netting. Vertical growth keeps fruit clean and straight, improves airflow, and makes harvest easy — a strong move against soil-borne disease.

  4. 4

    Water deeply and evenly

    Cucumbers are mostly water and need about 2.5 cm (1 in) per week, more in heat. Deep water at the base on a steady schedule; uneven moisture causes misshapen, hollow, or bitter fruit. Avoid wetting the leaves.

  5. 5

    Mulch and feed

    Once soil is warm, with straw or to hold moisture, suppress weeds, and keep fruit off the dirt. Cucumbers are hungry — work compost in at planting, then lightly with a balanced fertilizer when vines start to run and again at first fruit set.

  6. 6

    Protect early, uncover to pollinate

    Floating row cover early on shields seedlings from cucumber beetles and cold winds. But most varieties need bees, so remove the cover the moment flowers open to let insects — unless you're growing a parthenocarpic variety that sets fruit on its own.

  7. 7

    Pick early and often

    Harvest every 1–2 days at peak season, cutting fruit before it yellows or the seeds . Leaving even one cucumber to mature signals the vine to stop setting new fruit, so frequent picking keeps the harvest coming for weeks.

Gardener's notes

  • Cucumbers don't cross- with squash, pumpkins, or melons to change this year's flavor — that's a myth. Cross-pollination only matters if you save seed, and bitterness comes from stress and genetics, not from a nearby zucchini.
  • Don't panic over the first wave of flowers that drop without fruit — on monoecious varieties the earliest flowers are all male and simply can't set cucumbers; female flowers (with a tiny cucumber behind them) come a bit later.
  • the growing tip once vines reach the top of the trellis pushes energy into side shoots and fruit, and refrigerating cucumbers too cold is a common storage mistake — they keep best around 10–12.5°C (50–55°F), warmer than most fridges.

Varieties worth knowing

Marketmore 76
Classic open-pollinated monoecious slicer (~58 days); produces separate male and female flowers on the same plant, so the first flush of male flowers is normal and not a defect. Reliable, disease-resistant garden standard.
Boston Pickling
Heirloom monoecious pickling type (~55–60 days); needs bees to set fruit. Pick small for crisp pickles.
Diva
Gynoecious AND parthenocarpic (~58 days) — bears mostly female flowers and sets seedless, thin-skinned, bitter-free fruit without pollination, so it shines under row cover or in tunnels where pollinators are scarce.
Socrates / Beit Alpha types
Parthenocarpic greenhouse/tunnel cucumbers — keep these away from pollinated varieties, because stray pollen can cause misshapen or seedy fruit.
Gynoecious hybrids (e.g. 'The General')
Nearly all-female flowers for heavy, concentrated yield; seed packets usually include a few monoecious 'pollenizer' seeds (often dyed) — don't cull them or fruit set fails.

Common problems & fixes

Powdery mildew
Sign: White, talcum-like powder on the upper leaf surface, usually late season; leaves yellow and dry.
Fix: Space and trellis for airflow, water at the base, and plant resistant varieties. Sulfur or potassium-bicarbonate sprays help if caught early; remove badly affected leaves.
Downy mildew
Sign: Angular yellow blotches on the upper leaf bounded by veins, with grey-purple fuzz underneath in humid weather; spreads fast and can defoliate a plant.
Fix: There are no effective downy-mildew sprays for home gardeners — rely on resistant varieties, wide spacing, drip irrigation, and trellising for airflow. It blows in on wind, so scout often and remove infected debris.
Cucumber beetles + bacterial wilt
Sign: Striped or spotted yellow-and-black beetles chewing leaves and flowers; later, whole vines wilt and collapse even when watered — that's bacterial wilt the beetles carry in their gut.
Fix: Manage the beetles and you manage the wilt — there is no cure for an infected plant. Use row cover until flowering, hand-pick beetles, and remove wilted plants promptly. Pull the cover at bloom so bees can pollinate.
Bitter fruit
Sign: Sharp, bitter taste, worst at the stem end and just under the skin.
Fix: Bitterness comes from cucurbitacins that build up under stress — mainly hot, dry, erratic conditions — and varies by cultivar. Water evenly, mulch, harvest young, and grow bitter-free varieties (e.g. Diva). Peeling and trimming the stem end removes most of it; it is NOT caused by cross-pollination with squash or melon.
Misshapen or poorly filled fruit
Sign: Curled, pinched, or nubbin-ended cucumbers.
Fix: Usually incomplete pollination (too few bees, or row cover left on during bloom) or uneven watering — not disease. Encourage pollinators, keep moisture steady, and feed lightly.

Companions

Grows well with
CornBeansPeasRadishDillNasturtiumSunflower (as a living trellis)Marigold
Keep apart from
PotatoAromatic herbs like sageMelons and squash nearby (shared pests/diseases, not because of cross-pollination of flavor)

Harvest & storage

Harvest
Harvest 50–70 days after sowing, picking fruit while still firm, green, and slightly immature — before the skin yellows or seeds harden. Pickling types at 5–10 cm (2–4 in), slicers at 15–20 cm (6–8 in), burpless/Asian types longer. Cut with pruners rather than pulling to avoid damaging the vine, and pick every 1–2 days; frequent harvest keeps vines productive for weeks.
Storage
Store unwashed in the refrigerator at 10–12.5°C (50–55°F) for about 1 week — cucumbers are chilling-sensitive and turn watery and pitted below ~10°C (50°F), so the coldest part of the fridge actually shortens their life. Keep away from apples, tomatoes, and bananas, whose ethylene speeds yellowing. They don't cure or store long-term; eat fresh or pickle promptly.

Sources

This guide is curated from authoritative horticulture references — primarily US university Extension services, the USDA, and the RHS.