How to grow cucumbers — sowing to harvest in 60 days

How to grow cucumbers — sowing to harvest in 60 days

Cucumbers are one of the most rewarding crops in a beginner garden — a single healthy plant can give a family more cucumbers than they can eat. They're also one of the easiest to ruin: inconsistent water turns the fruit bitter, powdery mildew kills the vines by August, and unprotected outdoor plants in cool UK summers often fail to set fruit at all. This guide is the full season-one playbook for both US (warm-summer) and UK (cool-summer, often greenhouse) growing.

Track your cucumbers in Growli: Add your variety and zone to the Growli app and you'll get reminders for sowing, trellising, side-dressing, and the first signs of mildew on the leaves.

When to plant cucumbers

Cucumbers are frost-tender and warm-soil-loving. Direct-sow only when soil is at least 21°C / 70°F, or your seeds will rot. Approximate timing:

Cross-check your local last frost date, and see the starting seeds indoors guide for the lighting and bottom-heat setup that gets cucumbers off to a fast start.

Bush vs vining vs greenhouse cultivars

Three styles, each suited to a different garden. Pick before you buy seed.

Vining (outdoor) — US standard

Most US cucumber crops are vining, ridge-type plants that trail or climb. They need a trellis (a 6-foot panel works) and produce heavily for 4-6 weeks before mildew or beetles slow them. Reliable US cultivars:

• Marketmore 76 — the standard slicing cucumber for the northern US, 8-9 inch dark green fruit, resistant to scab, cucumber mosaic virus, and downy mildew. Available from Burpee, Johnny's Selected Seeds, and Park Seed in 2026.
• Straight Eight — heirloom, smooth dark green 8-inch fruit, AAS winner from 1935 and still widely sold.
• Bush Crop — bushy compact plant suited to small beds or containers, slicing-type fruit at 55 days.

Bush — compact, container-friendly

Bush cucumbers grow on short vines (2-3 feet) and are the best fit for raised beds, patios, and pots.

• Spacemaster 80 — productive on plants that stay under 3 feet, slicing-type 7-8 inch fruit.
• Bush Champion — heavy yield on compact 24-inch plants, popular with UK container growers.

Parthenocarpic / all-female (UK greenhouse standard)

Modern UK greenhouse cucumbers are parthenocarpic — the female flowers set fruit without pollination, which is essential under glass where bees can't reach the plants. These produce seedless, mild, burpless cucumbers and are the easiest type for a polytunnel or greenhouse:

• Carmen F1 — the UK greenhouse standard. Strong resistance to powdery mildew, scab, and leaf-spot. Straight glossy fruit up to 40 cm. Sold by Mr Fothergill's, Suttons, and D.T. Brown.
• Burpless Tasty Green F1 — bitter-free, ridge or greenhouse, tolerates summer heat, resistant to mildew. The most-recommended UK outdoor cucumber.

If you grow a parthenocarpic variety, don't plant ordinary outdoor cucumbers nearby — cross-pollination can make the parthenocarpic fruit bitter and seedy.

Soil and site

Cucumbers want:

• Full sun — 6+ hours of direct sun, more if you garden in a cool UK summer.
• Well-drained soil rich in organic matter. Heavy clay needs amending with compost.
• Slightly acidic to neutral pH — 6.0-7.0.
• Warm soil — cold soil stunts growth and rots seed. Use black plastic mulch or fleece for two weeks before sowing to warm the bed in cool zones.

Container growers: 20-30 litres (5-8 US gallons) per plant, with bagged potting mix — not garden soil, which compacts under watering.

Sowing and transplanting

Two routes:

Direct-sow (US warm zones)

Sow 1 inch deep, 2 seeds per spot, 18-24 inches apart for bush types and 36 inches apart for vining types climbing a trellis. Thin to the strongest seedling at the 2-true-leaf stage.

Transplant (UK + cool US zones)

Start indoors 3 weeks before transplant date. Cucumbers hate root disturbance — sow in 3-inch biodegradable pots or coir plugs that go straight into the ground. Harden off for a full week before planting out. Set the rootball at soil level; don't bury the stem.

For full bed planning, see our vegetable garden layout guide and use our plant spacing calculator for your specific cultivar.

Watering — the bitterness control

Inconsistent watering is the single biggest cause of bitter, deformed cucumbers. The rule: deep, regular, at the base.

• 1-2 inches of water per week in mild weather; daily watering once temperatures exceed 30°C/86°F.
• Water at the base — overhead watering wets the leaves and accelerates powdery mildew.
• Mulch heavily — 2-3 inches of straw or grass clippings stabilises soil moisture and root temperature. See our mulch primer.

Container plants need watering daily once temperatures rise.

Feeding

• At sowing: balanced 10-10-10 worked into the bed, or a starter dose of slow-release fertiliser in containers.
• At flowering / vine-run: switch to a higher-potassium feed (tomato fertiliser works) every 2 weeks until harvest stops.
• Avoid heavy nitrogen late — too much nitrogen produces lush leaves but few cucumbers.

Pollination — outdoor vs greenhouse

Outdoor cucumbers produce separate male and female flowers (the female has a small fruit behind the bloom). Bees move pollen between them. If you have no bees, hand-pollinate by transferring pollen with a small brush at mid-morning.

Greenhouse parthenocarpic cultivars (Carmen F1, Bella F1) do not need pollination — and crucially, must be protected from pollination to stay sweet. Remove male flowers if any appear, or grow in a closed greenhouse with no outdoor cucumbers nearby.

Companion planting

Cucumbers work in a polyculture bed. See our full companion planting guide for cucumbers for the matrix. Reliable pairings:

• Radishes — sown along the row, they break up soil and confuse cucumber beetles.
• Beans — fix nitrogen and don't compete for the same nutrients.
• Peas — same nitrogen-fixing benefit on a spring overlap.

Avoid planting cucumbers with potatoes or sage — both reduce cucumber vigor in trials, according to RHS guidance and US Extension consensus.

Pest watch

The three problems that will most likely hit your plants:

Powdery mildew

A white powder on the leaves that spreads fast in humid weather and kills vines before the season ends. Mostly preventable with airflow, base-watering, and resistant cultivars. Our dedicated powdery mildew on plants page covers the full diagnosis and the milk-spray treatment.

Spider mites

Tiny dots on the leaf underside; leaves turn stippled and crisp. Common in hot dry weather and on greenhouse plants. See the spider mites on cucumbers page for the full treatment plan.

Whitefly

Clouds of tiny white insects under the leaves, especially in greenhouses. They spread cucumber viruses. See whitefly on cucumbers for sticky-trap and biocontrol options. The broader whitefly identification page covers the lifecycle.

Cucumber beetles (US-only) are best deterred by floating row covers until flowering, then removed for pollinator access.

Trellising and training

Vining cucumbers produce cleaner, straighter fruit when trained up rather than left to sprawl. The benefits of a trellis:

• Straight, evenly-shaped fruit — sprawling plants produce curved cucumbers from contact with the soil.
• Better airflow — slower powdery mildew.
• Easier harvest — hanging fruit is visible and easy to pick.
• More space below — interplant lettuce, radishes, or basil at the trellis base.

A simple A-frame of bamboo canes, a panel of pig wire stapled to a wood frame, or a length of nylon netting between two posts all work. Tie the main stem loosely to the support every 12 inches; the side tendrils do the rest.

For greenhouse parthenocarpic cucumbers, train as a cordon — a single vertical stem with side shoots pinched at 2 leaves past the first fruit. This is the commercial Dutch greenhouse method and gives the highest yield per square foot.

When to harvest

Pick cucumbers before they turn yellow. Once a fruit yellows, the plant signals "seed production complete" and stops setting new fruit. The sizes:

• Slicing cucumbers: pick at 6-8 inches, before they bulk up.
• Pickling cucumbers: pick at 3-4 inches for crunch.
• Parthenocarpic (Carmen F1, Telegraph): pick at 30-35 cm.
• Bush types: pick at 5-6 inches.

Pick every other day at peak season — a missed cucumber turns the plant off for a week.

Related articles

• How to start a vegetable garden — the wider beginner roadmap
• Vegetable garden layout — where cucumbers fit in a bed
• Companion planting guide — the matrix for cucumbers
• Starting seeds indoors — the bottom-heat setup
• Powdery mildew on plants — diagnosis and treatment
• How to grow tomatoes — companion crop for the same bed
• Frost-date calculator — your local sow-out window
• USDA zones lookup — for transplant timing
• UK hardiness ratings — for southern vs northern UK timing

Reviewed and updated by the Growli editorial team. For questions, open Growli or email hello@getgrowli.app.