Growing Lettuce Indoors in the Winter

Growing lettuce indoors is a project I’ve wanted to tackle for a long time. We have a nice south-facing window in our kitchen, it’s perfect for growing plants.

This post on growing lettuce indoors will be a little different than most of my posts. Usually, I’m writing about things I know a lot about or projects we have already tackled and proven successful.

But growing lettuce indoors in the winter is new to us. In fact, this post is about our experiment with growing lettuce indoors. This is our first time trying it, so I am going to lay out for you what we are doing and then as our experience grows I will update this post with new advice.

Also, I’d really like to ask for your comments and suggestions. If you have experience growing lettuce indoors and would like to add your advice PLEASE feel free!

Why we want to grow lettuce indoors in the winter

Many of you know we do a lot of winter growing, we have 3 cold frames and a hoop house this year bursting with winter produce (to learn more about our year-round gardening start here). But lettuce is not the hardiest of the winter plants. We can usually only keep it growing until about the first of December in our cold frames. But we love having lettuce around to add with our other winter greens for salads.

When we moved into our new house 3 years ago, I immediately started checking out this beautiful south-facing window in our kitchen. For the last 3 winters, we have talked about growing some lettuce in this sunny spot. But because it is in our kitchen, Aj wanted it to look nice (we do a lot of entertaining here). So we bounced around several ideas and finally this year we landed on clay pots!

This window also has an east-facing partner so this entire spot really gets a lot of sunshine every day. More than any other windows in our house.

Our steps for Growing Lettuce Indoors

So here’s how we are trying to grow lettuce indoors this year

Start your Lettuce under lights

We grow all of our own seedlings each year using our seed starting set up. This time of the year it sits unused as its a bit too early for spring plantings. So I figured I should put the seed starter to good use and get the lettuce seedlings off to an extra good start by first growing them under the lights.

We started these lettuce seeds in early October and they have been under the lights since. You can see they have sized up very well and are ready to be transplanted. I think these big beautiful starts will give us our best chance at successfully growing lettuce indoors. My one worry is that these starts are used to 14 hours of light per day. Once they are in the window they will only be receiving 10 hours or less of sunlight during the winter. We will see how they react to this change. Lettuce is a plant that can grow with less light, so I’m hoping this bright window will be enough!

Transplant your seedlings into the pots

We bought eight 4-inch clay pots with saucers. In the hope of saving some potting soil, we filled the bottom of the pots with some gravel. Again we are experimenting a bit here. 4-inch pots are really not all that big so filling a third of them with gravel may turn out to be a mistake as it might limit root growth. But we’ll see. I can always take the gravel out for the next round.

I then covered the gravel with soil and transplanted the seedlings into the pot and filled up the remaining space. Then we watered them well.

We had about 16 total starts, I picked the 8 strongest and we used the rest in a salad.

I also choose the starts based on color. Again this is in a very public part of our house so we wanted it to look good. You will see, it really does look pretty cool!

Put your seedlings in a sunny window

Max out the sun as much as possible. These windows face our backyard so we don’t need to worry too much about privacy. We will keep the blinds on this window up and out of the way for this whole experiment.

Only 6 of the pots fit in the south-facing window so I put the other 2 in the east facing window.

Water, care and fertilizer

The plants are right over the sink so watering should be simple. Clay pots dry out fairly quickly so I figure we will need to water every 3 days.

Rotating the plants will be super important. If we want to avoid tall leggy plants that are leaning to the sun we will need to rotate the pots a 1/4 turn every couple of days. Again having them right over the sink will help us to remember to do this!

Fertilizer will be important. For this first test run, the seedlings are planted in an organic seed starting mix. This mix does have a little compost but not much, so we will need to give them a supplemental feeding of an organic fertilizer. For now, we will be using our liquid fish emulsion diluted to 1/2 strength. We will fertilize them once a week. I”m a little concerned about the smell of the fish emulsion. If that smell doesn’t go away within an hour or so then I think we will head down to our local nursery. They sell a granular organic fertilizer that we can try instead.

As you can see from the pictures, they look pretty cool!! If nothing else I will enjoy having some green in the house! We used 3 different types of lettuce this time. Our favorite red leaf lettuce, Tom Thumb which is the paler green (this is a mini butter crunch), and then our favorite full-size butter crunch. I think ultimately we will stick with leaf lettuces or the mini butter crunch. We want the quickest-growing types we can find. We planted these on Saturday (December 10). I’m hoping they are large enough to start harvesting leaves in 2 or 3 weeks (around Christmas). I’ve already started the next batch under the lights of the seed starter. If this project works out, we have several other south-facing windows that we may try this in!

So . . . here’s your chance. What advice do you have for me? Have any of you tried this before? What made it successful for you? What varieties did you grow? How soon were they ready for harvest? Leave your comments below! Thanks, Guys!