Long Cucumbers — DutchGreenhouses

The wrapped Dutch standard, and the fastest crop in the house

Long cucumber is the classic Dutch glasshouse cucumber, shipped shrink-wrapped to hold moisture in a fruit that is almost entirely water. It is sold by the piece to a tight length and straightness specification, so a fruit outside the grade has little value regardless of its weight. It is the primary Dutch long high-wire baseline.

What the crop needs

The plant is grown on substrate and carried on a high wire, and it moves fast: fruit fills in days, and the plant will abort a load it cannot support. Transpiration is high, so irrigation capacity and humidity control are sized for peaks rather than averages. Because the crop responds within days, climate faults are expressed almost immediately — which makes the crop unforgiving, and also makes it quick to diagnose.

What the greenhouse has to do

Cucumber pushes the climate system harder than tomato does. Transpiration is high and the crop answers within days, so irrigation capacity, humidity control and ventilation are sized for peak demand rather than for the seasonal average. A house dimensioned on averages runs out of headroom in exactly the weeks that decide the grade.

Cycle planning is a design input, not an operational detail. The crop is fast enough to run more than one planting in a year, and how many the house runs sets the heating profile, the lighting decision and the labour pattern together. Length and straightness are graded fruit by fruit, so even transmission and even water delivery across the whole floor are worth more than a strong specification at one point in the house.

DutchGreenhouses® specifies the structure, climate, screening and irrigation around the cucumber crop, its cycle and the local climate, so peak demand is carried and fruit holds the grade. Get in touch to plan a cucumber greenhouse.

Midi cucumbers

Shorter than a long cucumber, and a category that has moved.

Mini cucumbers

A label that has drifted further than any other in the crop.

Snack cucumbers

The smallest format, sold to be eaten whole.

Hydroponics

Substrate growing with drip supply and drain recirculation.

Climate

Heating, cooling, humidity control and carbon dioxide dosing.

Questions

Long cucumber, asked and answered

Why is cucumber considered a demanding crop to climate-control?

It grows and fruits faster than other fruiting vegetables, so an error in humidity or irrigation shows within days and there is little time to correct it before it reaches the grade.

How many crops a year can a cucumber house run?

It depends on the cycle chosen, the lighting and the market being supplied. The crop is fast enough to allow several, which is why cycle planning is a design input rather than an operational detail.

Why is the fruit wrapped?

To slow water loss. The fruit is largely water and loses condition quickly once picked, so wrapping protects shelf life rather than appearance alone.

Crop data

Long cucumbers — reference values

Reference values from the DutchGreenhouses crop model, each traced to its Dutch source below. Ranges describe published practice across systems and seasons; a project setpoint is calculated for the actual greenhouse, crop and climate.

Day climateMedium confidence¹²³

Air temperature: 24–24.8 °C
Relative humidity: 73–79 %
Vapour-pressure deficit: 0.62–0.86 kPa
Daily light integral: 16–20 mol/m²/d
Photoperiod: 16–18.5 h
CO₂ concentration: 600–800 ppm

Night climateMedium confidence¹⁴⁵

Air temperature: 21–22.4 °C
Relative humidity: 86–95 %
Vapour-pressure deficit: 0.19–0.35 kPa

Irrigation and root zoneMedium confidence¹²⁶

Supply EC: 2.8–3.5 mS/cm
Supply pH: 5.4–5.8 pH

Where these come from

WUR / Carpineti et al., 2024, WPR-1343 — Long-cucumber night transpiration. WUR report · High confidence · E035Controlled daylightless cells, cultivar Dee Flexion; strong treatment evidence but not a universal commercial recipe.
Kas als Energiebron / Botany & Plant Lighting, 2025, project 24019 — Lit high-wire cucumber 2024–2025. Public Dutch trial · High confidence · E036One 24-week winter crop and cultivar; capacity and source–sink strategy are system-specific.
Kas als Energiebron / Botany & Plant Lighting, 2025, project 23011 — Lit high-wire cucumber 2023–2024. Public Dutch trial · High confidence · E037One winter crop with three cultivars; observed settings are not universal optima.
WUR / de Gelder, 2016, GTB-1408 — High humidity and minimal moisture removal. WUR report · High confidence · E038Specific double-glazed greenhouse with film screen; demonstrates system dependence, not a humidity optimum.
WUR / de Zwart et al., 2017, GTB-1444 — Screens, humidity and dehumidification. WUR report · High confidence · E039System-energy relationship; crop risk still depends on dew, uniformity, air movement and disease pressure.
WUR, 2026, WPR-1263 — Cucumber substrate/fertigation context. WUR report · Medium confidence · E043Pathogen/root-environment experiment, not a commercial production optimum; retained only as supporting context.

These are reference values, not a specification. DutchGreenhouses does not publish project setpoints; those are calculated per greenhouse, crop and location.

From the knowledge base