Greenhouses and Glazing for Better Lettuce Growing

There is no question that the production of greenhouse grown lettuce and greens is evolving as the opportunities and demand expand and mature.

Determining the right greenhouse for growing leafy greens is dependent on a few factors including climate, budget and whether this is an expansion or a new build. From small scale to large scale, greenhouses provide an ideal environment for growing lettuce and other produce. In this segment we will look at style of the structure and glazing options GGS can offer to get the most for your budget.

Freestanding Greenhouses

A GGS Double Poly Freestanding Greenhouse is a great choice for local markets, organic growers, and specialty market growers, growing either soil grown or hydroponic grown greens. The most popular width is 30’ wide (other widths are available, for consultation call or connect to us through our contact form). Length is incremental in 4 foot or 6 foot sections so it is easy to build to the requirements of your crop plan. If you are hanging lights to provide supplemental lighting this can easily be supported by single tube crossties, making the freestanding greenhouse easily adaptable for your requirements. Freestanding Greenhouses also have a number of ventilation options, including forced air fan venting or natural ventilation with swinging side vents and / or rollup sides. These houses are strong, built to last and an economical cost-effective choice for smaller and entry level commercial greenhouse operations.

Gutter Connected Greenhouse

Gutter Connected and Widespan Greenhouses

The most popular single peak width of most GGS Gutter Connected Greenhouses are 21’ or 24’ from gutter to gutter. To optimize space and hydroponic growing systems for lettuce on a larger scale, growers often choose to go with a Widespan structure. This is the same in appearance to the regular bay but reinforced crossties are used to eliminate a row of posts. The bay has 2 peaks and the standard widths include 32’, 36’, 42’ and 48’ wide. For height, we recommend 14’ or 16’ under the gutter to give lots of room for adequate air circulation and flow, hanging supplemental lighting, and natural light distribution. Made with hot dipped galvanized steel, all GGS commercial greenhouse structures meet or surpass local agricultural building codes as well as take in local weather considerations for strength and durability.

Greenhouse Glazing

Successful lettuce production facilities use curved glass, poly carbonate, and double poly options. Each one has its benefits which make them premier choices for lettuce growing environments.

Nothing gives you more light penetration than a curved glass greenhouse. Lettuce thrives in high light environments so choosing a GGS Curved Glass greenhouse ensures you will maximize the value of natural sunlight. The GGS Curved Glass gothic design has proven to give the extra strength needed to take the worry out of winter snow loads. This is also the driest greenhouse for growers who need to control higher humidity levels. The expert designed glazing bars have condensation channels built into each extrusion so water droplets on the roof are collected and directed outside the greenhouse. Remember, with glass, the higher the intensity of summer sunlight, meaning shade curtains are recommended during the middle of the day to prevent stress and tip burn on the leaves of the crop.

Next to Curved Glass on the roof 8mm PCSS is the choice of many professional growers. What PCSS (Polycarbonate Structured Sheets) give up in light transmission they make up for in heat retention, and the light levels for clear 8mm PCSS are still above 80%. Additionally, in high hail zones PCSS tends to be the preferred choice because the flexibility of the polycarbonate material allows for enough give to reduce the risk of hail damage.

The Low Profile Glass or Venlo Greenhouse design is another option, but for natural ventilation the Curved Glass and PCSS roofs provide more air exchanges. Low profile greenhouses also come in widespan widths for greenhouse facilities with ponds and large hydroponic systems. They are not recommended in areas with hail.

Double poly is another option for covering your greenhouse roof. Double poly is economical and effective for providing some heat retention. Typically poly roofs need to be recovered every 4 years, though growers with high light requirements may select to replace their roof plastic sooner. This decision depends on your location, crop needs, and the amount of usage of supplemental grow lights. For growers capitalizing on natural ventilation the double poly greenhouse offers many options.

Leaf Lettuce


Every grower knows how important ventilation is to the health of your crop. Leafy Greens are a cool-weather crop so ventilation is especially important to ensure that temperatures can be maintained in the desired range. Whether you choose natural ventilation of forced air will be significantly impacted by the geographic region where the greenhouse is built.

GGS is a greenhouse ventilation expert. We can help guide you through all the options, and consider your location, crop needs, and all the other systems that make up the total greenhouse environment. It is by integrating all the different systems into your design that we build the ideal controlled environment for your crop.

Read about our ventilation options here.

Each GGS structure will provide an excellent yield, but each style has unique differences in how the grower can best manage the crop. For over forty years, GGS has been working with all growers to design and manufacture greenhouses for success. Contact us today to consult with our experts and learn more about your greenhouse options.

The greenhouse environment and the water management of a lettuce crop are key to quality product. Climate, water and light are important factors we will discuss in our next blog.

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