What Nutrients to Use for Hydroponic Lettuce?

Lettuce is one of the most grown vegetables on earth, and for good reasons! It’s healthy, grows quickly and easily, and can be cultivated all year long under the right conditions.

Hydroponic lettuce grows faster, stronger, and healthier than soil-grown lettuce, but it requires liquid nutrients. It even tastes better.

What nutrients does hydroponic lettuce need to grow?

Hydroponic lettuce plants need a variety of essential macro nutrients including nitrogen, phosphorus, magnesium, calcium, and potassium to promote propert growth. Further, lettuce plants grown in hydroponic systems also require a handful of vital micro nutrients such as copper, boron, iron, and manganese in order to be healthy and thrive.

Read on below to learn exactly what nutrients to use for hydroponic lettuce!

What Nutrients Does Hydroponic Lettuce Need To Grow?

Growing hydroponic lettuce is both fun and rewarding. Once you get the hang of it, you can produce fresh lettuce on a weekly, biweekly, or monthly basis. 

But, in order to grow happy and thriving hydroponic lettuce, you must provide the right environment, including water, lighting, oxygen, proper temperatures, and of course, the right nutrients.

Hydroponic lettuce needs all the same natural nutrients that their soil-grown counterparts need to thrive outdoors in the ground. 

The most important nutrients for lettuce, in general, are nitrogen, phosphorus, potassium, calcium, and magnesium.

Hydroponic lettuce requires a stable pH range between 5.5 and 6.0, 5.8 being the ideal number. The hydroponic growing system’s EC should register around 1.2 to 1.5 mS/cm.

Every two weeks, drain your hydroponic reservoir and clean it out. Fill the system back up with fresh water and then add more hydroponic nutrients.

Always use your pH and EC meters after water changes to ensure that the system is running at the right specs for your lettuce to thrive. Otherwise, you may come back tomorrow and find your whole crop is withering away or turning yellow.

For beginners, a well-balanced water-soluble fertilizer is suggested for hydroponic lettuce growing operations (such as a 10-10-10 fertilizer solution). Advanced hydroponic gardeners may prefer a slightly higher NPK.

Organic Hydroponic Nutrients For Lettuce

Organic Hydroponic Nutrients For Lettuce

So long as the nutrients you feed your hydroponic lettuce don’t contain chemicals or pesticides, they may be considered safe and organic. 

Just a few of the most popular organic hydroponic nutrients include:


Believe it or not, cow manure, and other various types of animal manure (such as guano, mentioned below), are a wonderful solution for organic hydroponic nutrients.

But, first, you need to learn how to mix the manure into a liquid form because you can’t just add solid manure to your hydroponic reserve without throwing the system out of what.

The manure must be mixed with mater, at a ratio of approximately 10 parts water to 1 part manure. Once it is strained, the liquid nutrients can be measured and added to your hydroponic system.


Making guano liquid nutrients for your hydroponic lettuce works the same way we outline above for turning mature into liquid nutrients.

Simply add the guano (bat manure) to 10 parts waters and then add the strained liquid to your hydroponic reservoir.

Guano is highly prefered by experienced growers thanks to it’s powerful decomposing microbes, and its high levels of phosphorus and nitrogen. In fact, it is one most saught after manures in the world.


Fish smulsion, or fish fertilizer, is another great choice for oganic hydroponic nutrients.

Most organic fish emulsion products are high in nitrogen, phosphorus, potassium, as well as the micro-nutrients calcium, magnesium, sulfur, sodium and chlorine.

Honestly, there are few natural nutrient sources to add into the water better than those which are derived from fish.

Bone Meal

Bone meal is one of the most classic organic nutrients there are, that’s why hydroponics experts created a liquid version years ago.

This ingredient made up of dried and powdered animal bones, typically from cows.

You can buy these popular hydroponic organic nutrients online or at a local hydroponics supply store.

Blood Meal

Blood meal is another classic garden suppliment that has long sense been upgraded to work with hydroponics.

Today you can find liquid blood meal in most garden centers as well as large online retailers.

Simply add a bit of this into your hydroponic reservoir and you’re good to go.


Compost is a tricky source of organic nutrients to use for hydroponic lettuce. L

ike with manure, and other solids, the compost must be turned into liquid before it may be allowed to enter the hydroponic system and be fed to the plants.

Mix rich organic compost into water, similiarly to how you mix manure (10 parts water to 1 part solid).

Once it is strained, it may be added directly to your hydroponic growing systems water reservoir.

Other Plant-based Materials

You can also use partially decomposed and even fresh cut plant-based materials (like grass, leaves, and plant clippings) to make organic liquid nutrients.

For example, you can keep the weeds from your garden in a container, and your fresh grass clippings, and mix then mix them into a five-gallon bucket with water.

Leave the bucket with gass and weeds sit in the sun for 3 to 5 days and then strain it out. You’ll be left with a black nutrient solution rich in macro and micro nutrients essential to hydroponic lettuce.

What is the Best Nutrient Solution for Hydroponic Lettuce?

When it comes to properly fertilize your hydroponic lettuce with liquid nutrients, there are tons of great options to choose from.

MasterBlend Fertilizer 8-15-36

The MasterBlend Fertilizer 8-15-36 is a favorite with hydroponic gardeners that grow lettuce, as the formula is specially designed for the crop.

Other great nutrient solutions for hydroponic lettuce include:

Humboldts Secret Base A & B Bundle

The Humboldts Secret Base A & B Bundle is another fan favorite for hydroponic gardeners and larger hydroponic growing operations as well. Simply mix both bottles of the product together and let them balance your pH and feed your plants!

Mr Fulvic Organic

The MR Fulvic Organic hydroponic nutrients are another super popular (natural) solution. This product’s main ingredient is humic shale. More or less, Mr. Fulvic includes 30 million-year-old compost.

UrbanLeaf Liquid Plant Food Hydroponic Nutrients

This liquid plant food is one of the all-around best products for hydroponic plants. Whether you’re growing lettuce, spinach, or strawberries and tomatoes, UrbanLeaf has a proper product for your hydroponic system!

Fish Head Farms Organic Soil Conditioner

As the name suggests, this potent hydroponic fertilizer consists of some of nature’s finest organic materials; fish heads. These fish heads aren’t rolly polly, and you won’t want them in your soup, but they sure will make your lettuce healthy!

How to Use Nutrients for Hydroponic Lettuce?

Using hydroponic nutrients to fertilize your hydroponic lettuce is quite simple. All you need to do is measure the correct quantity, mix it, and introduce it into your hydroponic systems water reservoir.

Most of the time, this consists of measuring out a few caps of nutrients into several liters or gallons of water. 

You can use a digital pH and EC meter to check the nutrient levels present in the water after you apply them. 

Just make sure to give it up to 15 minutes to spread around and circulate first, otherwise, the reading won’t be accurate. 

In the following sections, we break down the process of fertilizing hydroponic lettuce with liquid nutrients in even greater detail.

How Often

The type of hydroponic system you use, and how you choose to maintain it, determine how often you will need to fertilize it with liquid nutrients. 

Most hydroponic growing systems work best when you change the water in the reservoir, including liquid fertilizer, every 15 days or so.

That said, hydroponic operations that are small-scale may benefit from a water change every 7 to 10 days, including fresh liquid nutrients.


The amount of water that your hydroponic reservoir holds is the number one determining factor as to how much nutrients you should add to your system. 

Larger systems require a higher amount of liquid nutrients, as the more water a system contains, the more diluted the nutrient solution becomes.

Your lettuce plants prefer a stable pH level of 5.5 to 6.0, in most hydroponic growing systems. 

Double check the pH level of your system approximately 15 to 30 minutes after adding nutrients. If you’ve added too much, or too little, consider using a pH adjusting product.

Ways to Use

There is one proper way to introduce fertilizer to your hydroponic system: turning it into liquid and pouring it into the reservoir. 

Once the hydroponic nutrients are introduced into the system’s reservoir, they are free to flow into the roots of your lettuce plants. Healthy plants will take up as many nutrients as they want/need and continue to thrive when pH levels are well-balanced.

Depending on the type of hydroponic nutrient solution product you’re using, the mixing process may differ. But, aside from that, all proper hydroponic nutrients go into systems via a liquid form.

Shelf Life

The average liquid nutrients designed for hydroponic systems have a shelf life of approximately 10 years (give or take 1 or 2 years). That said, the nutrients need to be stored properly or the shelf life is dramatically shorter (1 to 2 seasons).

Best practices for storing hydroponic nutrients include placing the nutrients in a dark and dry location. Keep the light level low, and the nutrients away from excessive moisture. Cabinets and garage shelves are excellent locations for storing hydroponic nutrients.

Can I Make My Own Hydroponic Nutrient Solution for Lettuce?

If you don’t want to buy a mass-produced hydroponic nutrient solution for lettuce, you may surely make your own. 

The process is fairly simple, but you need to gather some materials before you begin. 

Here’s a list of the most commonly used ingredients for making a DIY hydroponic nutrient solution:

  • Iron
  • Manganese
  • Boron
  • Zinc
  • Copper
  • Molybdenum
  • Guano
  • Bark compost
  • Sulfate
  • Corn Liquor
  • Compost
  • Mushrooms
  • Potassium

Whatever ingredients you decide to purchase, or produce from your garden (such as compost, or mushrooms), they will need to be dried and powdered. After your ingredients are powdered, they need mixed together (into a container with water) and then introduced into your hydroponic system.

It’s best to measure your DIY liquid nutrients with a pH meter before adding it to your hydroponic system’s reservoir. For lettuce, the pH level of your hydroponic water (after nutrients are added to it) should be approximately 5.5 to 6.0.

Why Does Hydroponic Lettuce With Liquid Nutrients Have White Stuff?

The white stuff that you may notice on your hydroponic lettuce with liquid nutrients is called powdery mildew. 

Powdery mildew appears as a white floury covering. It is a fungal disease that needs to be treated immediately.

To treat powdery mildew, remove as many affected leaves as possible and then apply baking soda to the rest of the plants.

Make sure to sprinkle the baking powder evenly across the plants, both the affected areas and the areas where powdery mildew hasn’t spread yet.

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