IGS’ Head of Science Tanveer Khan gives an expert breakdown on the process of growing lettuce through vertical farming
For the second instalment of our Crop Focus series on nursery plants, Tanveer homes in on growing lettuce seedlings using vertical farming technology.
Drawing on decades of experience in the field and in research labs, Tanveer and her team at our Crop Research Centre focus on how we can use agritech to alter taste, nutritional value, and grow crops at scale sustainability.
If I were to ask you to picture how to grow lettuce, you’d likely think of a field stretching into the horizon, punctuated by rows of crops as far as the eye can see. Now picture vertical farming technology – a tall stack of trays with heads of lettuce cultivated under rows of LEDs. Some contrast, right?
Growing lettuce with vertical farming technology doesn’t just make for a more efficient use of land (one of our 12-metre Growth Towers offers a 520-metre squared growing area with a 41-metre physical footprint), it can also mitigate the environmental impact as there’s no need for harmful fertilisers or chemicals. At IGS, we’ve been conducting trials on how to grow different types of lettuce since 2020. Here’s how we go about it.
How we conduct crop trials
It all starts with a thorough review of the available literature. As team, we’ll sit down and review the current science, taking inspiration from greenhouse and outdoor growing, and see what works and what doesn’t. This gives us the primary seed for our research.
Our current pipeline has five levels: from proof of concept all the way through to productisation. In proof of concept and level one, we check the effects of the substrate, watering, temperature and humidity and work to choose the best conditions. In level two, we test different light regimes for the best yield, quality, and energy output for our customers. We continue to test and refine these parameters for the subsequent two stages before reaching the final level, also known as productisation. It’s important that we test multiple different types of lettuce to help reduce errors, increase robustness, and scale up to deliver the best product for our customers.
Utilising different growing methods
Different combinations of nutrients work for different crops – the same is true when growing lettuce using vertical farming technology. We add these nutrients to a fertigation tank where they are dissolved in water and automatically delivered to the crops growing in trays within the Growth Towers. This gives the lettuce the optimal amount of water and nutrients, recycling any excess to ensure nothing is wasted and making for efficient use of resource.
When it comes to lighting, we’ve found that red and blue are the primary spectra we can utilise to really affect the final crop. It needs to be in the proper ratio, though. If you add too much blue, it can cause the lettuce to taste quite bitter. If you use too much far-red, on the other hand, it makes the crop too tall. This isn’t a desired characteristic, so it’s important that we work out the correct lighting ratio and stick to it. We also use green light as part of the ratio to achieve the perfect blend.
Landing on the perfect lettuce
The easiest lettuce for us to grow is green Batavia. This is one of the more common varieties, and you’ll find it everywhere from lunchtime salads to delicious sandwiches and wraps. We're really happy with the how the lettuce turns out, and it makes for a lush, beautiful crop.
We’ve also conducted trials on Cecilia lettuce (which is from the butterhead family, and can be recognised due to its compact, uniform heads). We ran a proof of concept to see how similar vertically farmed Cecilia lettuce would be to that grown in a greenhouse. This was an important part of our research process as we were able to look at what worked best in other types of controlled agriculture, and use it to form the basis of our own recipes.
A hybrid approach
Lettuce plugs can be grown using vertical farming technology as part of a hybrid approach with traditional agriculture. Seeds (or cuttings) can be germinated in an external germination chamber, before being moved into an IGS Growth Tower. This has the added advantage of being pest and disease free, as well as enabling faster growth cycles. From here they can be transported to either open field or a greenhouse, where they can embark on their final stages of growth before harvesting.
Why work with IGS
With over a decade’s experience producing vertical farming technology, IGS combines crop science, engineering and agronomy to empower growers across multiple continents.
We use Total Controlled Environment Agriculture (TCEA) to fine tune every aspect of the growing environment, allowing for consistent, planet-friendly crops. 2023 saw IGS sign a contract with ReFarm to build a world-first GigaFarm in Dubai, capable of replacing 1% of the UAE’s food imports and growing two billion plants each year.
Tanveer Khan PhD is Head of Science at IGS. She works at our Crop Research Centre in Dundee, Scotland, leading a team of crop scientists to develop optimal growth recipes for our customers across the world, as well as staying ahead of the curve on the latest developments in crop science.
Want to learn more about Tanveer’s work, or how vertical farming can be integrated into your operations? Get in touch.
