How to grow hydroponic lettuce

If you’re looking for a straightforward first hydroponics crop, you’ll undoubtedly want to consider lettuces (Lactuca sativa). Growing hydroponic lettuces is pretty straight forward, which makes it an ideal choice for those just getting started with their own systems.

In this post, you will learn the best type of lettuces to grow, what systems work best and how to optimise your system for a bountiful yield. Lettuce gets started!

What’re The Best Lettuces to Grow?

With so many different types of lettuce to grow, how do you know which is the best for hydroponics? We’ve got some good news for you: all types of lettuce grow extremely well within hydroponic systems.

We’ve got more good news for you too…As these leafy greens only take 45 to 85 days (depending on the type) to grow a full head, if you don’t like what you’ve planted the first time, it won’t be long before you can get started with the next crop. Below we’ve listed a few of our favourite lettuce crops:

Romaine Lettuce

Sometimes known as cos lettuce, romaine is a great variety to try and, for us, is the perfect summer crop as they’re just so tasty. Not only is the romaine lettuce a main ingredient in Caesar salads, but the leaves are the ideal replacement for burger buns!

Butterhead Lettuce

The butterhead is the undisputed champion of hydroponic lettuces. The flavor is slightly sweet but not overpowering, and as the name might suggest, the leaves have a buttery texture to them.

Loose Leaf

This is a bit of a catch-all term for several sub-types such as Bijou, Conarde (sometimes known as “oak leaf”) and Mazurosso which don’t form a head, instead, their leaves are joined at the stem. With many different types available, they all add a little something due to the different tastes and textures.


It might shock you to learn that iceberg lettuces grow well in a hydroponics system; the only thing to keep in mind is that unlike butterhead and loose-leaf lettuces and icebergs take twice as long for the heads to be ready to harvest compared to the more leafy types listed above.

The Most Important Things To Know About Hydroponic Lettuces

While these are the perfect crops for beginners due to their simplicity, you still need to know a few things (plus, it’ll help you achieve larger harvests).


The best-tasting lettuce grows in cooler temperatures. If it gets too hot, the plants will start to flower, which leaves them tasting bitter, which isn’t what you want on your salad.

PeriodLow Temp.High Temp.
Day68°F / 20°C77°F / 25°C
Night60°F / 15°C65°F / 18°C

Electrical Conductivity

Lettuce tends to grow well with an electrical conductivity of 1.4 mS/cm.


Lettuces prefer a pH value of 5.5-6.0. You can monitor pH levels using one of these hydroponic pH meters.

Grow Period

As we mentioned earlier, typically, it takes around 40-50 days to harvest leafy varieties of lettuce, while those that need a more established head, such as romaine and iceberg, can take between 80 – 85 days.


Lettuce isn’t demanding when it comes to lighting requirements. 10-12 hours of moderate light is sufficient for lettuce to grow well.


When it comes to getting the proper hydroponic nutrient levels for lettuce you’re going to want to do a little planning first. To grow well, lettuce requires a solution that’s high in nitrogen and phosphorus but lower in potassium. Thankfully there are off-the-shelf nutrient solutions designed just for lettuce.

Grow Medium

Lettuce isn’t particularly fussy when it comes to growing medium so the choice is ultimately up to you; here are some of our favourites:

  • sand,
  • pine shavings,
  • coco fibre,
  • river rock,
  • Rockwool,
  • vermiculite

Each has its pros and cons, however, our go-to choices are rock wool and coconut coir.

What Systems Work Best?

Lettuce really is a versatile little crop and grows well in both a Deep Water Culture (DWC), Nutrient-Film Technique (NFT) and Ebb & Flow systems. If this is your first time developing a crop in a hydroponics system then just find one that works for you and go with it, unless you’re running a large commercial operation then you can change at any time without too much of an issue.

The Bottom Line

So there you have it, our guide on how to grow hydroponic lettuces. Hopefully, the outline above provided a good summary of which varieties grow best, which system to use and what to look for when setting up your system.

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