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Growing lettuce indoors in winter isn’t just possible—it’s fast and foolproof. Depending on the fool. If you’ve ever been personally victimized by a bag of store-bought greens that turned to sludge overnight, this is for you.

Karen Bertelsen holds a tray of lettuce with black standard poodle looking on.

Growing lettuce indoors isn't some high-maintenance process requiring hydroponic systems, spreadsheets, and a minor in botany. This is as simple as sprinkling seeds into dirt and turning on a light. And then watering of course. Everyone forgets watering.

Also, I'm a fan of the spreadsheet - you just don't need one for this.

You can be harvesting lettuce 30 days after planting it.

I normally grow lettuce in my Aerogarden in the winter which works really well to grow full heads of lettuce. This winter I wanted to try growing a cut and come again type of lettuce where you harvest the leaves when they're young by cutting them a little above soil level. Then the lettuce sprouts again, letting you harvest this way 2-3 times.

This is the first time I've tried growing lettuce this way indoors and it couldn't have gone better. Here's how it should go for you:

Growth Timeline

Day 1: Plant seeds.
Day 3: Seeds sprout.
Day 14: Lettuce is recognizable and filling in.
Day 25: First small harvest—enough for one salad.
One Month: The tray is bursting full with lettuce, ready for serious harvesting.

A rectangular glass container holding spring greens.

My first harvest. It was enough for one small salad, picked 25 days after seeding.

But it was fresh lettuce and a lot more was on the way.

Here's how to grow it yourself.

Table of Contents

The Setup

I planted Bon Vivant lettuce mix—a blend of leafy greens that that I've never had success with when growing outside. But you can use any lettuce seed.

If you've never grown anything from seed before read this post on how to start seeds so you know the general rules.

The Tray: Drill or cut holes into a standard seed-starting tray. You want something that will hold soil but also drain water.
Soil: Fill the tray with damp potting soil.
The Rows: No rulers. No fancy dibblers. Just drag a finger through the soil to make 3 rows.
The Seeds: Heavy seeding. Pinching and sprinkling them in like you're salting a batch of fries.
Light: Two T5 grow lights*

*I have a biggish seed starting setup in my basement and I use 4' lights, but you can use 2' lights. They're a good size for a single tray and can probably fit in a corner or windowsill of your kitchen.

At this point, I stepped back, gave my lettuce one last encouraging nod, and let nature do its thing. Unlike my beets, lettuce isn't prone to existential crises over nutrients or humidity. I didn't experience any damping off or yellowing leaves with the lettuce.

Lettuce just grows, quietly and efficiently, like the introvert of the plant world.

Growth

A green plastic pint basket filled with indoor grown lettuce greens.

The best size for harvesting greens this way is when the leaves are about 6" long.

Indoor Lettuce Photojournal

Growing lettuce indoors, day 3, lettuce sprouts.

Day 3 (January 25th): Seeds sprout.

Day 6 (January 28th): Fully formed cotyledon leaves.

Growing lettuce indoors, day 14 the greens are filling in.

Day 9 (January 31st): True leaves forming.

Day 14 (February 5th): Filling in.

Growing lettuce under lights day18, bushy growth where you can't see the soil anymore.

Small white salad bowl filled with homegrown spring greens.

Day 18 (February 9th): Can't see the soil anymore.

Day 25 (February 16th): First harvest. A handful of small, delicate greens—just enough for a showoff salad.

Beet salad with apples and lettuce on a flow blue plate.

The last apple from the espalier tree and pickled beets (from the garden) added to the lettuce with goat cheese and a balsamic dressing. Some pecans too. It's basically this beet salad except I swapped roasted beets for pickled beets.

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Seed starting tray with lettuce growing and first harvest taken.

This is Day 25 growth.

Note the small squareish section I cut for my tiny salad.

Harvesting spring greens cut and come again style with scissors.

Salad with beets, carrots, cheese and red cabbage in a black bowl.

1 month: Cutting an entire row will fill a medium sized salad bowl (8" across)

Make your salad go further by loading it with other things. Here I added carrots, red cabbage and thin slices of raw beet. (all from last summer's garden harvest) There's cheese in there too!

8" stainless steel bowl (measuring tape across) filled with lettuce grown under lights indoors.

The Secret to Continuous Harvesting

Different growth levels in cut and come again lettuce grown in a seed starting tray.

In the photo above you can see how much the first tiny salad cut (far left) I made is growing back 15 days after cutting. The rest of the row was cut a few days later (so it's smaller), and the lettuce at the back-right hasn't been cut at all yet.

Lettuce isn’t a one-hit wonder if you cut it right. The trick? Snip it 1.5 inches above the soil, leaving the growing tip intact. This isn’t deforestation—it’s strategic harvesting. The lettuce rebounds, growing back for round two (and three, if you’re lucky).

Growing Lettuce Indoors

Yield: A lot of salad.

Growing lettuce indoors under 2 lights works astonishingly well.
Here's how to do it.

Materials

10x20 seed starting tray (with drainage holes cut into bottom)
Potting soil
Lettuce seeds
water
2xT5 grow lights

Instructions

Prep the Tray – Use a tray with drainage holes and fill it with damp potting soil.
Make Rows – Drag a finger through the soil to create three shallow rows.
Sow Seeds – Sprinkle lettuce seeds heavily along the rows—no need to space them out.
Cover & Water – Lightly dust with dry soil, mist with water, and press gently to ensure good seed-to-soil contact.
Humidity Boost – Cover with plastic wrap or a humidity dome to keep moisture in.
Light & Growth – Remove the cover once seeds sprout and place them under T5 grow lights.
Watering – Water from below as needed or use a felt-wicking system. Misting leaves daily also helps.
Harvest – When leaves reach 4–6 inches, cut above the growing tip. Harvesting one row at a time keeps things tidy.

Notes

You can use scissors or a drill to create drainage holes in your tray.

I've never tried this in a sunny window, but go ahead and give it a shot. It's gardening. You don't know until you try.

What You’re Wondering

Do I Need a Fan

I didn't use one.

How Often Do I Water

When the top third of the soil is dry. OR use a felt watering system like mine and you never have to worry about watering.

How Long Will It Keep Producing?

You’ll get 2–3 solid harvests before the leaves turn tough or bitter.

Storing the Lettuce

It's best picked and used the same day but it will last for a couple of days (no more) in an airtight container in the fridge.

For never-ending lettuce, seed a NEW tray right after you cut your first full harvest. This will keep you in perpetual lettuce.

Thirty days ago, this was just a tray of dirt and some lettuce seeds. Now it’s a full-blown salad factory. No recalls, no wilt, no regrets.

Are you inspired to try it?