How to Grow Lettuce Indoors Hydroponically

Growing lettuce indoors hydroponically is extremely easy to do. When I first started out into hydroponics I started growing lettuce because it required a cheap light compared to fruiting plants like tomatoes, cucumber and so on. There are a few different types of hydroponic setups that you can choose from when growing lettuce as well. When growing lettuce or any leafy green they also need nutrients but very little and any nutrients that you buy will last a very long time when growing lettuce.

After you get things set up it is not hard to stagger a few seedlings and have a steady harvest of lettuce every 3 to 4 weeks.

Ways To Grow Lettuce Hydroponically

There are a few hydroponic methods that we can use to grow the lettuce indoors hydroponically and the most common way is the Kratky method or DWC which means deep water culture. Next if you are wondering what the difference is one has air stones and the other has nothing and is quite basic but works like a charm! I guess another way to look at it is one way is a lot cheaper than the other as well. I think it really depends what stage you are in with your garden.

Kratky Method

If this is your first time hearing about the Kratky method do not worry, chances are you all ready know about it or have seen it in one version or another.

The picture above shows how the Kratky Method actually works and the science behind it. As the roots grow they need more air or they will drown in the water but as they plant grows it drinks the water creating air zone. The air zone allows air roots to start growing which increase the plants growth. The most important thing to keep in mind when watering the lettuce you must only fill it half way do not fill it up past the air roots. Over watering will lead to root rot and plant health issues so it is best to avoid it.

Lettuce usually takes about 30 days plus or minus a few days. So most cases you will not need to add much water if any and you do not need to change out the water supply since it has such a sort growing cycle.

Growing lettuce with the Kratky method works great and you can grow a head of lettuce in almost any container as long as you cover it so the sunlight does not get into the area were the roots are growing this will cause algae and other unwanted problems in your water and root zone.

Using a small tote or old bottles that are 1.5L and bigger seem to work great. During summer and warmer months they grow great in the window or all year around in the window depending on where you live. Here in Canada it gets quite cold and if your window has a cold draft it will stun the growth of the lettuce dramatically.

After everything is set up you just need to add nutrients to the water to help boost plant growth and keep them nice and healthy!


Deep Water Culture

Taking a look at the DWC setup we can see the major difference is that it has a air pump, airline tube and a air stone! If you are feeling lost about the new equipment we have some useful articles on:

Air Pumps For HydroponicsBest Hydroponic Air Stones – Best Air Tubing For Hydroponics

The Deep Water Culture setup will cost a little more since you need to buy a air pump, air stone and some air tubing but if you can afford the costs which can be as cheap as $15 bucks or less! The picture above shows how you can support more plants at once with the air stone and in the same bucket. Some people use a styrofoam sheet as the lid since it floats on the water so you can easily see the current water level.

With DWC you can keep more roots in the water thanks to the use of the air stone it adds a lot of oxygen to the water which helps maximize nutrient uptake so your lettuce will grow crazy!

When growing in DWC you can use the same bukets as the Kratky method just add the air pump and air stone. After trying both of these hydroponic setups I do like the DWC better because of the growth rate that is shown.

Growing in DWC is also great for fruiting plants like tomatoes, peppers, etc. If you plan to grow these in the future you will need to invest in some good indoor grow lights for hydroponics and there are many on the market that can help keep your plants growing healthy and green.

Best Lettuce Grow Light

These some of the best lights for growing lettuce indoors all year around. They are from companies that I have used personally and have had great results in both lettuce growth rate along with amazing customer support.

If you are looking to keep the electricity bill down and be as efficient as possible I would really recommend going with this Vivosun led grow light. It offers enough coverage for a 3×3 grow area of lettuce! By going with led you will not have to replace bulbs or deal with the light producing to much heat in the grow area.

300W LED Grow Light Specifications:

  • Dimensions: 13.5x9x3 inches
  • Item Weight: 6.5 lbs
  • Input Voltage: AC100-240V
  • Avg. Power Draw: 135W±3%
  • Frequency: 50-60Hz
  • Working Temp.: -20℃~+40℃/-4℉~104℉
  • (60pcs) High Intensity 5W LEDs
  • Lifespan: 100,000 hours

Those are the technical specifications listed by visiosun for this 300w led grow light.

T5 Grow Lights

The T5 Grow Lights have been around since indoor growing has been around basically! They are a staple that has proven results and a lot of growers I know use them as well.

Here you can see how someone would set up there T5 Grow Lights growing lettuce along with other plants. You can also mix in led lights if you wanted to have one of each.

Keep in mind that the T5 grow lights do have 4 bulbs that last quite some time but eventually need replacing. If you choose to go with the led grow lights you will have no maintenance since they last for years.

Feeding Nutrients To Lettuce

After our lettuce is finished the seedling stage it is ready for its feeding of nutrients! Since we are growing lettuce we want to go with something that has proven results and has been around for a while. Root Farm is a great company that has great customer support anytime I needed to contact them. For those reasons I choose to go with root farm for my leafy greens and it works great.

At first it seemed very confusing until I seen this feeding chart! It shows us how much to feed our lettuce of the Base Nutrient and the Root Farm All Purpose Supplement.

These bottles of nutrients will last you a long time if you are growing a few plants per month. Keep in mind different plants will require different amounts of nutrients some may eat more then others so this chat and feeding routine is best only for lettuce and other leafy greens.