Green Oakleaf Lettuce — DutchGreenhouses

A lobed, soft leaf grown for shape rather than for weight

Green oakleaf has a distinctively lobed leaf and an open, soft head. It is grown for leaf shape, which is what it contributes to a mixed pack or a wholehead display, rather than for mass. The softer leaf limits how far it travels well.

What the crop needs

The crop is short-cycle and hydroponic. The open head structure makes it less prone to the inner-leaf problems that affect dense types, but the soft leaf is easily damaged in harvest and packing. Handling is therefore a larger share of the grade outcome than it is for a crispy head.

What the greenhouse has to do

Oakleaf is grown for shape, and shape is easier to damage than weight. The lobed leaf catches on handling and the head does not protect itself the way a dense type does, so the harvest route, the internal transport and the pack area are laid out to move the crop with as few transfers as possible.

Cycle and uniformity do the rest. The crop turns many times a year, so density and the recirculating water system decide annual output. A soft, open leaf transpires freely, which helps at the margins but leaves the canopy sensitive to still air, so ventilation and air movement are specified for the whole floor rather than for the average.

DutchGreenhouses® designs the structure, climate, screening and irrigation around the lettuce type, its system and the local climate, so cycles turn at the head quality the market grades on. Get in touch to plan a lettuce greenhouse.

Butterhead lettuce

Soft, loosely wrapped leaves, and the type least tolerant of handling.

Greenleaf / Batavia lettuce

A firmer, more robust head than butterhead, and it travels better.

Romaine lettuce

The upright head, and the tipburn risk that comes with it.

Hydroponics

Substrate growing with drip supply and drain recirculation.

Climate

Heating, cooling, humidity control and carbon dioxide dosing.

Questions

Green oakleaf lettuce, asked and answered

Is head weight or head count the right target?

Lettuce is sold by the head, so the count reaching grade in a year decides revenue. A heavier head grown more slowly can earn less than a lighter head on a shorter cycle.

Does the cultivar matter more than the type?

For head mass, density tolerance and tipburn risk, yes. Those are cultivar properties, which is why a lettuce project is planned around a named cultivar rather than around the type alone.

What causes tipburn?

Calcium not reaching the fastest-growing leaf margins, driven by transpiration and root pressure rather than by supply. Climate control addresses it; adding calcium to the solution generally does not.

Crop data

Green oakleaf lettuce — 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 confidence¹

Air temperature: 21–22.7 °C
Relative humidity: 60–80 %
Daily light integral: 11.5–13.2 mol/m²/d
CO₂ concentration: 1000–1100 ppm

Irrigation and root zoneMedium confidence¹

Supply EC: 1.6–1.8 mS/cm
Supply pH: 5.5–6 pH

Where these come from

WUR, 2018, WPR-813 — Lettuce on water under glass with LED. WUR research report · High confidence · E067Primary direct evidence, but one research greenhouse and four named lettuce types/cultivars. Numeric values are operating observations, not universal optima.

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