Growing lettuce indoors is easy, it doesn't require a lot of room, and the supplies are readily available, plus it might be healthier and safer for you than buying it from the grocery stores. 

With the latest lettuce contamination scare and recall, I feel a lot better picking up my tray of salad greens and clipping off fresh leaves each time I want a salad.

Growing lettuce indoors isn't as hard as you would think. Growing heads of lettuce is possible inside, but growing young leaf lettuce or salad mixes is the way to go.

In a little over 30-days you can be making a salad with greens you've grown yourself!

Growing Lettuce Indoors

Let's run through the process of growing lettuce indoors from seed. The method shown below can be used for straight leaf lettuces (any kind) or salad mixes.

Equipment & Supplies

Here is the equipment that you'll need.

Optional items that grow lettuce faster.

You can use LED shop lights to grow lettuce. The more expensive grow lights work too, but aren't necessary for growing greens. Lights made by Commercial Electric work well for me, plus you can connect them together reducing the number of plugs needed.

Use un-chlorinated water when growing lettuce indoors (or any other plant for that matter).  A calcium based fertilizer works best because salts won't build up in the soil and your plants will grow more lush. Nectar of the Gods is an amazing fertilizer. It seems expensive but you don't use much. I saw results first time using it.

More Information on Home Microgreens

I have much more information on how to grow lettuce indoors posted on Home Microgreens.

Not only lettuce but other greens that you can grow year around indoors!

Getting Started

I guess I forgot you'll need a home for your lettuce tray once you've seeded it. I use a cheap plastic rack, but you can get a fancier rack, use a table, end table, or any flat area where you can place a light over the tray.

Set up your heat mat and plug it in. Don't worry it doesn't get very hot, just warms the soil media and increases germination rate and speed. 

Watch the video below to see the process and I'll discuss it more afterward.

That was pretty simple, right? 

You can choose to pre-wet the soil before planting, but mine was damp and I'd rather top spray then bottom water once the plants start growing.

It's easy to over-seed the tray, so try to stay around 350 to 400 seeds per tray. Using too many seeds will not allow the plants to grow well as they'll compete with each other. 

Growing the Plants

Lettuce greens or salad mix is very easy to grow. 

As the heat mat warms up the soil, condensation will accumulate on the cover, this is good as the rise in humidity is good for seed germination and the young seedlings.

growing lettuce indoors

Leave the clear cover over the tray until there is a good carpet of seedlings poking up out of the soil. 

At this time, take off the clear cover so the seedlings can receive more direct light. 

It's also time to start bottom watering. 

growing lettuce indoors seedlings

Lettuce mix seedlings 6-days after planting.

Bottom watering is simple. Lift off the top tray and pour water or fertilizer mixture into the bottom tray to about an half-inch deep.

Slowly place the top tray down into the water. The soil will absorb the water as you lower the tray. 

Some growers use more water, lower the tray and then lift it out again and allow it to drain. I use less water and leave it inside the lower tray. 

It's okay if the top gets dry, the roots will find the moist soil.

Use a cheap moisture meter to test the wetness level. After a while, you'll be able to tell by the weight of the tray. 

Fertilizing Lettuce Greens

Most good soil mixes will have the necessary nutrients to grow lettuce well for 30 days or so.

However, using a liquid fertilizer will make your lettuce grow faster and bigger. 

There are many fertilizers that will do the job. Since we won't be top watering, liquid feed by bottom watering is the best way to go.

I use Oregon's Only Nectar of the Gods. Although it isn't labeled organic, it really is. The way it's made doesn't allow labeling as such because it's not a nitrogen salt based fertilizer. Those type of fertilizers have a tendency to accumulate salts in the soil. Rather Nectar is a calcium based fertilizer. 

Remember, we're going to compost the soil after we use it, so we don't want salts to build up.

Learn more at Oregon's Only website.

That's All There's to Growing Lettuce Indoors

Keep the greens under the light and watered and in 30 or so days you'll be able to cut your fresh greens.

Below are the greens from the seeds I planted in the video after 15-days.

growing lettuce indoors 15-days

Lettuce Greens 15-days after planting.

Harvesting Lettuce Greens

Harvesting is a simple process. All you need is a sharp knife or a clean pair of scissors.

Grasp a few greens by the top and cut the plant just above the soil surface. 

Obviously, try not to get any soil. It's a good idea to wash your greens before eating anyway.

Below is a tray of lettuce that I'm harvesting, I clip off enough to make my salad and put the tray back under the lights. 

harvesting lettuce grown indoors

Work your way down the tray as you go. From that tray in the image I got six good sized salads. 

Notice that the first cutting of lettuce is growing back.

harvested lettuce growing back

Time will tell if allowing the lettuce to grow back is worth the time and space. I'll update the post once I have an answer. 

Try Growing Lettuce Indoors

Growing lettuce indoors during the winter or anytime if you live in an apartment is a great way to add nutrition and good food to your diet when fresh produce has to travel hundreds if not thousands of miles to your grocery store. 

The initial investment can be a bit pricey, but once the basics are bought all you need is a bit of soil and new seeds. 

The quart bottles of fertilizer will last a very long time, since you only using milliliters at a time. 

Please leave a comment below if you've grown lettuce indoors or want to try. Share with your friends and don't forget to subscribe to get updates, both for the website and the YouTube channel.

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how to grow lettuce indoors
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About the Author T.Marsh

Hi, my name is Todd. My View From the Woods documents my journey of gardening, growing microgreens, preserving food, searching for a homestead, and hiking with my new Springer Spaniel, Caden.

Follow me on Instagram at @myviewfromthewoods

  • Good luck on your journey. Thank you so much for the information. I have just started doing micro greens. I have harvested one 10×20 pan of broccoli micro green. I did not know about growing lettuce indoors. I am going to try right away. I don’t have a clear dome or the seed, and my excitement is going to make the anticipation unbearable, LOL. I have been using True Leaf Market for seeds and some supplies. They are great but the pandemic has slowed the process to a crawl.. Thank you again. You are my new best friend.. You are appreciated.

    • Thank you Christy! I appreciate the kind words.
      There will be a new post and video on growing trays of baby leaf lettuce indoors very soon. Including lettuce seed added to the Home Microgreens Store. Don’t be afraid to use my TrueLeaf Market affiliate link in the sidebar if you don’t buy from the Home Microgreens Store!
      Good luck!

  • I have read and put to use all your information, But where can I get the heat pad and what kind of lettuce is that your growing? Thank you for all your help

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