How to Grow Cucumbers
On this page
- Cucumber (Cucumis sativus)
- Quick Facts
- At a Glance
- Greenhouse or Outdoors? The Trick to Growing Cucumbers
- Growth Stages
- Soil & Growing Conditions
- Harvest & Storage
- The Tomato-Cucumber Myth -- and What Coffee Grounds A...
- Diseases
- Pests
- Plan your Cucumbers planting
- Growing Cucumber in another region
- Sources
- Frequently Asked Questions
Cucumbers are frost-tender and germinate best around 21°C soil temperature; sow once you can provide that warmth, and they're usually ready to harvest 50–70 days later.
The short answer
- Ready in
- 50–70 days
- Site
- 6+ hours of sun, soil pH 6–6.5
- Biggest risk
- Powdery mildew
Core growing advice on this page is checked against named horticultural sources — see References.
Cucumber (Cucumis sativus)
9 sources cited · Verified
Quick Facts
At a Glance
Greenhouse or Outdoors? The Trick to Growing Cucumbers
Both work, but they're different plants in practice. Greenhouse (indoor) types are smooth-skinned and all-female, cropping earlier and more heavily under cover; outdoor "ridge" types have tougher, often knobbly skins and are bred to tolerate the cooler, more variable conditions outside. Buy seed labelled for the situation you're growing in -- an indoor variety sown outdoors won't fruit as reliably.
The real trick RHS keeps coming back to is consistency: sow under cover at 21°C, don't plant out until frost risk has fully passed, and then water evenly -- erratic watering, more than almost anything else, is what causes bitter fruit and blossom end rot.
Growth Stages
| Stage | BBCH | Notes |
|---|---|---|
| Sowing & Germination | 0 | Cucumbers are almost always started under cover. SOWING DEPTH: sow one seed 1-2cm (half to three-quarter inch) deep in the centre of a 10cm pot of peat-free compost, placing the seed on its edge (side). TIMING: heated greenhouse mid-February to mid-March; unheated greenhouse or polytunnel in April; outdoor (ridge) types in late April, or sown direct into their final positions in late May/early June (up to three seeds per station, thinned to the strongest). Germinate at about 21°C (70°F) in a heated propagator or a plastic bag on a warm windowsill; seedlings appear in one to two weeks. Never sow cold or early outdoors - the crop is frost-tender. |
| Planting Out & Training | 3 | Harden off greenhouse plants before moving to their final spot from late May; plant outdoor (ridge) cucumbers out only from early June once local temperatures are reliably above 12°C (53°F) and all frost has passed. SPACING: set plants 30cm (1ft) apart, or one per container at least 30cm wide and deep. Train the climbing stems up tall bamboo canes, strings or a wigwam, tying them in as they establish. Keep plants warm and sheltered; in the greenhouse aim for 18-25°C and raise humidity in hot spells. |
| Flowering & Pollination | 6 | Cucumbers carry separate male and female flowers (the female has a tiny fruit behind the bloom). GREENHOUSE all-female F1 types set seedless fruit without pollination - remove any occasional male flowers, as pollination makes the fruit bitter and misshapen. RIDGE (outdoor) types need their male flowers for insect pollination, so leave them. Pinch out (stop) the growing tips to steer the plant: in the greenhouse pinch the main stem at the roof and side-shoots two leaves beyond a female flower; outdoors pinch the main stem once the plant has seven leaves. Begin high-potash (tomato) feeding as flowering starts. |
| Fruit Development | 7 | Fertilised (or, on all-female types, unpollinated) female flowers swell into fruit. This is the thirstiest stage: keep the soil or compost evenly moist, watering at the base to avoid wetting the leaves, and daily in hot weather - erratic watering causes bitter or misshapen fruit. Feed every 10-14 days with a high-potash liquid feed. Support heavy fruits and keep picking so the plant channels energy into new cucumbers rather than seed. |
| Harvest | 8 | Pick fruits young, while uniformly green and firm with a slightly rounded tip, before they yellow or swell (over-mature and yellowing cucumbers turn bitter and stop the plant cropping). Sizes at picking: mini types about 8cm (3in), small-fruited about 15cm (6in), full-sized 20-25cm (8-10in). Cut the stem cleanly with a knife or secateurs rather than pulling, and harvest every few days - regular picking keeps more fruit coming, from mid-summer to mid-autumn under glass and over a shorter season outdoors. Typical time from sowing to first harvest is about 50-70 days. Store cut cucumbers cool (about 7-10°C) and humid for around a week. |
Soil & Growing Conditions
Harvest & Storage
The Tomato-Cucumber Myth -- and What Coffee Grounds Actually Do
Can tomatoes and cucumbers be planted together? Yes -- checked directly against Ask Extension's own companion-planting guidance, which finds no garden-planting incompatibility between them at all: "You can, but you need to make sure that you leave enough room... so they don't deprive each other of sun, water and nutrients." The "can't be planted together" idea most likely comes from a real but different fact: Purdue University's Vegetable Crops Hotline warns to "avoid stor[ing] cucumbers together with ethylene producing fruit such as ripening tomatoes" once harvested, since cucumbers are unusually ethylene-sensitive and spoil faster near them. That's a fridge rule, not a garden one -- the two plants grow fine side by side.
What do coffee grounds do? Less than the folklore suggests. Washington State University Extension tested this directly: used grounds are close to pH-neutral, not acidic as widely believed, and "fresh grounds are demonstrably phytotoxic to a variety of plants" -- WSU records "reduced seed germination and plant growth" where they've been used raw, and advises against them anywhere you're growing from seed. Composted (at no more than 20% of a compost pile) or used as a thin, covered layer, they're a fine soil amendment; sprinkled straight onto a seed bed, they can do more harm than good.
Diseases
Pests
Plan your Cucumbers planting
Timing for Cucumbers follows soil temperature and frost, not the calendar date. The Global vegetable planting calendar explains the method. To work out where it fits in your beds, sketch your plot in the free Garden Layout Planner.
Growing Cucumber in another region
Sowing dates, frost timing and local advice differ by country. Use the guide for where you garden.
Sources
These 2 sources are specific to this region. The full list of 9 sources behind this guide (Clemson Cooperative Extension, FAO EcoCrop, Global Biodiversity Information Facility (GBIF) and others) is in the references of our UK guide to cucumbers; they describe the plant itself, which is the same wherever it grows.
Frequently Asked Questions
How long do cucumbers take to grow?
Typically 50–70 days, depending on cultivar and growing conditions.
What soil pH do cucumbers need?
A pH of about 6–6.5. That span reflects genuine variation between the authorities we cite rather than a single agreed figure — the References section lists each source's exact range.
What problems affect cucumbers?
Our data links 8 diseases and 9 pests to this crop. See the sections above for each one and how to manage it.
Plan next season before the problems start
This page gives you the thresholds; the planner turns them into your own calendar. It works from what you can observe and measure in your garden rather than from dates written for somebody else’s latitude.
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How this guide is put together
The growing data on this page — sowing windows, pests, diseases, soil and site requirements — comes from named horticultural sources, listed in References below, checked against international horticultural research and extension sources. An automated pipeline assembles that verified data into the page you're reading: it selects which facts to lead with and builds the surrounding prose and layout. It does not invent a date, a source or a number — where a verified value for a field isn't available, the page leaves it out rather than guessing. A person reviews and publishes each page; nothing goes live unverified.
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Last verified 2026-08-06
Where To Go From Here
Take this crop from reading into a written plan for your own beds.
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Plan the next step
Use the printable SoilCommander planner for your region to turn this guide into sowing dates, bed layouts and weekly garden tasks.