Growing lettuce indoors

Have you ever aspired to being a vegetable gardener, but don’t have the space outside? Why not try to grow lettuces, which can be grown inside very successfully?

Lettuce can be grown indoors throughout the year. The plants will grow well in pots or planter boxes, provided they get 4 – 6 hours of sunlight per day, and are watered regularly. An alternative way to grow lettuce inside is to grow it hydroponically.

One of the most popular plants to grow in your vegetable garden is lettuce. They can also be grown inside, where you can control the conditions to encourage the seeds to germinate and the plants to grow.

Growing lettuce indoors

Lettuce grown indoors will either be in pots or planter boxes. These must drain efficiently, so water cannot be retained by the soil. Plastic is a better option for the container than clay. The plants must be positioned so they get enough sunlight and the soil must be kept damp.

Lettuce plants growing indoors in a pot or planter tray need a steady amount of water.

Clay absorbs water, which means that the soil in the pot could dry out, making it more difficult to keep the soil damp enough for the plants.

The pot and the soil must both drain efficiently.

Use a potting mix from your nursery or garden shop that is rich in the correct nutrients and which will drain well.

When you plant the seeds, you can sow them on top of the soil in the pot.

When the seedlings sprout, you can thin them out and transplant some of them.

Grow the lettuce plants in an area that gets regular sunlight.

Growing lettuce indoors in winter

Although lettuce is a cool-season crop, the plants are sensitive to very cold temperatures. They respond well to being grown indoors in winter, where the temperatures are mild. The plants will need to get enough warm light–ideally, 4 – 6 hours of light per day.

Lettuce is a cool season crop, but is susceptible to very low temperatures, so it won’t grow well outdoors in winter.

You can grow them successfully indoors in winter.

Lettuce needs about 4 – 6 hours of sunlight a day, which means growing them near a window, or even under lights.

To find out more about how lettuce relies on light, read about lettuce and full sun.

Apart from the light, you must make sure that your lettuce plants have a steady supply of water.

Keep the soil in the pot/s damp to at least an inch below the surface.

Growing lettuce from seed

To grow lettuce from seed, the soil must be prepared carefully. The seeds are very small, so they are often pelleted. They can be sown on the top of the soil, which must be kept damp but not soggy. The germinating seeds will need to be protected from very hot and very cold temperatures.

Before you plant the lettuce seeds, make sure you prepare the soil properly.

It should not have clods and clumps, so you won’t lose the seeds, which are often pelleted.

Make sure the soil has the correct amount and level of nutrients.

A lettuce plant gets most of its nutrients and water via the roots, so you must keep the soil moist.

Beginning the germination inside  will protect the seeds from the cold or heat that could prevent them from germinating.

Growing lettuce under grow lights

Growing lettuce inside means they may not get the correct type and amount of light; lettuce requires at least 4 – 6 hours of light per day. Growing lights can help to control these conditions. The best lights to use are blue-red LED lights that can be left on for up to 14 hours a day.

Growing lettuce indoors allows you to control the amount of light they receive.

Special growing lights will deliver the correct amount of light and heat for a lettuce plant.

The best lights for growing lettuce are blue-red LED lights, which should mimic the normal patterns of the sun, so that the lettuce plants will follow their normal growth cycles.

The lights should be left on for up to 14 hours a day.

Growing lettuce in water

Growing lettuce plants hydroponically, in water, is one way of ensuring they get the correct water supply. Lettuce plants will need some support, so it’s best to use a growing tower.

Lettuce can be quite a fussy plant when it comes to water, so growing it hydroponically can be very successful.

The water that the plant grows also contains a solution of nutrients to feed the plant.

Lettuce plants need some sort of support, with the roots dangling into the water.

A growth tower, which is set up to support the plant correctly and allow the roots to hang in the water solution.

Lettuce that is grown hydroponically must get enough sun, but mustn’t get too hot.

Before growing your lettuce plants in water, find out more about Hydroponic Lettuce.

Growing lettuce indoors in a greenhouse

Lettuce plants are very sensitive to water, light and temperature. The advantage of growing lettuce in a greenhouse is that these elements can be controlled. Under optimal conditions, lettuce plants will grow in nearly half the time it takes for them to grow outdoors.

The advantage of growing lettuce in a greenhouse is that you can control the temperature.

However, you must take into account that lettuce is a cool-season crop.

This doesn’t only mean heating the greenhouse in winter, but you’ll also need to cool it in summer.

Find out the temperature tolerance of lettuce.

When you plant the seeds, prepare the soil in the beds thoroughly and plant the seeds near the surface.

Lettuce plants grown in a greenhouse can take only 4 to 5 weeks to grow, as opposed to 10 to 12 weeks outside.

Because you can control the climate in the greenhouse, you don’t need to plant the lettuce seeds all at one time.

Plant some seeds every couple of weeks and you’ll be able to harvest plants throughout the season.

Growing lettuce in a pot

Lettuces can grow successfully in pots, provided they get the correct amount of water and light. The plants must be grown in soil and a pot that drain well. Lettuces need direct sunlight that is not too hot, so the pot should be placed near a window, or in a covered, well-lit spot.

Lettuce plants can grow well in pots that are placed in bright sunlight, as long as they don’t get too hot.

It’s very important that the plants get a steady supply of the correct amount of water.

One of the potential problems with growing plants in a pot is that the water won’t drain sufficiently.

You can avoid this by making sure that you use the correct soil, which will drain well.

Fortunately, the roots of lettuce plants are fairly shallow and are not likely to become bound in the pot.

However, they do need enough water, because the plant gets most of its water and nutrients from the roots, as opposed from the leaves too.

The trick is to keep the soil in the pot damp.

Put your finger into the soil to about an inch (2.5 cm) from the surface and check that it is damp to that depth.


So, there you have it.

Lettuce is one crop you can grow successfully inside with just a little effort. 

Keep the light bright, but not too hot, the temperature mild and the soil damp and you’ll be eating your way through your own lettuce patch in no time.

About the author

Greg Volente

Greg Volente holds a Naturalist Certificate from the Morton Arboretum, worked for The Nature Conservancy leading environmental education programs and doing natural areas restoration, and worked in the soil science research & testing lab at Michigan State University. Besides gardening, he's an avid wildflower enthusiast, and loves botanizing, hiking, and backpacking.