Lettuce has been grown and enjoyed all over, from Ancient Egypt to Outer Space.

This crisp, watery vegetable is incredibly versatile.

It comes in four different varieties: Crisphead, butterhead, loose-leaf and romaine.

It’s used in salads, tops juicy burgers, and even acts as a healthy substitute for bread.

And it’s no wonder why we use it for so many things.

Lettuce is full of antioxidants, which help prevent damage caused by unstable molecules in our bodies.

It’s also super easy to grow hydroponically.

That’s why lettuce is one of the most popular hydroponic crops.

We grow it in our Pure Greens Container Farms, which use nutrient film technique (NFT) and deep floating technique (DFT) hydroponic systems to grow a variety of leafy greens.

In this article, you’ll learn how to grow lettuce using a hydroponic system.

Getting Started

Use your growing medium, or a seed starter to sow your lettuce seeds.

We use rockwool cubes to start seeds for our hydroponic systems. 

Rockwool, made from spun basalt fibers, has a naturally high pH.

Therefore, if you choose to use it in your system, be sure to balance the pH before planting anything in it. 

You should expect about 75% to 80% of your seeds to germinate properly, so you will only need to sow one seed per cube. Keep in mind this number will vary based on the type of lettuce you’re growing.

Or you can sow more and thin out the seedlings as they grow.

Slow growth is a bad sign, Pure Greens Head Grower Andrew Wise says.

If you don’t see any growth within two weeks, you should start over.

Transplant the baby lettuce to its permanent home once it has four to six mature leaves and its roots are sticking out of the bottom of the growing medium.

Guide to Profitable Crops - Lettuce

Caring for Hydroponic Lettuce

Luckily, “Hydroponic lettuce is pretty easy to grow,” Andrew says.

We give all of our plants 18 hours of light and 6 hours of darkness each day using full-spectrum LED bulbs.

Depending on your setup and bulb type, you may need to reduce the amount of light you give your plants.

Lettuce also grows best in cooler environments.

Keep the air temperature between 45 and 75 degrees for best results.

In hydroponic growing, lettuce is prone to calcium deficiency, according to Andrew.

“Ensure calcium levels are correct in the nutrient solution,” he recommends. “This can lead to tip burn, a very common problem with lettuce.”

Tip burn limits the appearance and shelf life of lettuce and leads to slime developing in the head, making it unsellable.

While growing lettuce, there are a few signs that will tell you how well the plant is growing.

“Discoloration and necrosis are good signs something is wrong,” explains Andrew. “Stunted growth is another good indicator.”

Paying attention to these signs will help you make necessary adjustments to save your crops’ life.

Harvesting Lettuce

Unless you’re growing crisp head lettuce, like iceberg, you can harvest individual leaves from your lettuce crops without removing the entire head.

It should take only three weeks for your lettuce to be ready for you to harvest individual leaves.

Simply cut off bigger outer leaves, letting the inner ones continue to grow.

Alternatively, you can wait for the entire head to develop. This should take five to six weeks.

To harvest an entire head of lettuce, Andrew recommends cutting the roots off while leaving the head intact.

“Wrap the crown in a wet paper towel or place it in a cup of water,” he says. “This will extend the shelf life.”

Now you can grow lettuce like a pro!

For more information on hydroponic farming, visit our website or call 602-753-3469.