Growing lettuce indoors has great environmental benefits.
Over the past few years, there has been a fluctuation in the price of lettuce coming from California. The Salinas Valley, where much of North America’s lettuce comes from, has seen severe rain storms this past year. The extra water has flooded fields, delayed planting and caused hundreds of thousands of dollars in crop damage. In the fall of 2022, the same area was affected by a disease which struck lettuce crops. As a result of these events, the price of lettuce shot up, ranging from $9.99 for a three-pack of romaine (this is compared to an average price of $3.99 per pack).
Some farms are switching to growing lettuce indoors to help continue to supply customers with lettuce despite the climate events. Researchers from the Centre for Environment and Sustainability in Surrey found that lettuce grown indoors will produce, on average, 50% more leaves and up to 300% faster than lettuce that had been grown outdoors in the field. This is much quicker than current outdoor production, which ranges between 65 days from the beginning of germination to harvest for warmer months and up to 120 days for winter-planted lettuce.
The researchers also found that in controlled indoor environments, growing lettuce indoors yields twice as much lettuce compared to crops grown in fields. This is 3.68 kilograms of lettuce per square metre from indoor farms compared to an average of 1.88 kilograms from conventional farms. Researchers also found that iceberg lettuce grown indoors was consistently productive, yielding an average of 7.45 kilos per square metre.
Growing lettuce indoors in vertical stacking arrangements rather than horizontally increased the chances of a bigger crop. Moreover, lettuces grown in aquaponic nutrient systems produced the greatest yield. Aquaponics combines aquaculture (the cultivation of aquatic animals) and hydroponics (cultivating plants in water). It creates a mutually beneficial relationship between the fish and the plants, resulting in a closed-loop ecosystem. Aquaponics can be grown using a fish tank, a hydroponic grow bed (the plant absorbs the nitrates and other nutrients from the water, effectively filtering and improving its quality of fish), and water return (where cleaned and oxygenated water is returned to the fish tank.).
The benefits of growing lettuce indoors include:
- Year-round production – Indoor growing allows lettuce to be grown throughout the year regardless of the external climate.
- Controlled environment – Growing lettuce indoors and controlling factors such as temperature, humidity, and light can be controlled in indoor environments, minimizing the impact of weather fluctuations, pests, and diseases. Environmental impact can also be minimized by using UFO LED high bay lights.
- Extended growing seasons- Indoor conditions can help extend the growing season for lettuce varieties that might traditionally only grow during certain times of the year.
- Reduces impact from pests: Growing lettuce indoors leads to fewer issues with common pests like aphids, slugs, and snails. Indoor growing also eliminates the need for pesticides.
- Water efficiency: Water in growing systems, such as hydroponics or aquaponic systems, requires less water because the water is recirculated and not lost to evaporation or runoff.
- Local and sustainable: Indoor growing reduces the need for long-distance transportation and encourages a more environmentally friendly food chain.
The indoor growing industry probably won’t replace outdoor growing completely, but it can help fill in gaps in the supply chain, especially as climate change impacts crop growing. If California continues to experience floods and diseases that negatively impact lettuce crops, they might consider switching to indoor growing. While the initial cost for grow lights, containers, space, etc, might be high, it may be worth it in the long run and reduce the lost crops. It will also help keep customers happy as they will continue to be able to purchase lettuce at reasonable prices.
