How to Start Growing Lettuce Indoors for the Freshest Salads

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 than buying it from 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 are possible inside, but growing young leaf lettuce or salad mixes are the way to go.

In a little over 30 days, you can make 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.

• 10 by 20-inch planting tray with holes
• 10 by 20-inch planting tray without holes
• Clear Tray Cover
• Potting mix – I like Coco Loco
• LED Lights
• Salad Mix Seeds

Optional items that grow lettuce faster.

• Heat Mat
• Calcium Based Fertilizer

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, 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 lusher.

Nectar of the Gods is an amazing fertilizer. It seems expensive, but you don’t use it much. I saw the results the 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

Don’t forget you’d 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, warms the soil media, and increases germination rate and speed. 

Watch the video below to see the process, and I’ll discuss it later.

That was pretty simple, right? 

You can pre-wet the soil before planting, but mine was damp. I 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 compete with each other. 

Growing the Plants

Lettuce greens or salad mix is very easy to grow. 

As the heat mat warms the soil, condensation accumulates on the cover. This is good as the rise in humidity is good for seed germination and the young seedlings.

Leave the clear cover over the tray until a good carpet of seedlings pokes out of the soil. 

Take off the clear cover now so the seedlings can receive more direct light. 

It’s also time to start bottom watering. 

Lettuce mix seedlings six days after planting.

Bottom watering is simple. Lift off the top tray and pour water or fertilizer mixture into the bottom tray to about a 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 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

Good soil mixes will have the necessary nutrients to grow lettuce well for 30 days.

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

Many fertilizers will do the job. Since we won’t be top watering, liquid feed by bottom watering is the best way.

I use Oregon’s Only Nectar of the Gods. Although it isn’t labeled organic, it is. The way it’s made doesn’t allow labeling as such because it’s not a nitrogen salt-based fertilizer. Those types of fertilizers tend 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 water; 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.

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 above the soil surface. 

Try not to get any soil. It’s a good idea to wash your greens before eating anyway.

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

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.

Time will tell if letting the lettuce 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 travels hundreds, if not thousands, of miles to your grocery store. 

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

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

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

There are more updated baby leaf lettuce and microgreens articles on HomeMicrogreens.com.

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