A Guide to Growing Lettuce Indoors

Looking for a guide to growing lettuce indoors effectively? Check out our helpful guide on how to care and water lettuce today!

Maybe you’re in a fifth-floor walkup with no green space. Maybe you’re tired of fending off birds, bugs, and bunnies in your garden. Or maybe you simply want to enjoy crisp, homegrown lettuce all year round.

Whatever your reasons are for wanting to grow lettuce indoors, you'll be happy to know it's easy to grow fresh leafy greens in your home.

In this guide, we'll explain everything you need to know, including what type of lettuce to grow, how to care for it, and what supplies you’ll need for success. Let's dig in!

How to Grow Lettuce Indoors

Lettuce is a cool-weather crop that suffers when temperatures climb too high outdoors. It’s also a plant that thrives when grown hydroponically.1 This makes lettuce a perfect choice for indoor gardening in either hydroponics vs soil.

The basic requirements are simple:

  • A sunny window or grow light if grown indoors
  • Lettuce seedlings or seeds
  • Potting soil and seed trays, if growing in soil
  • An AeroGarden system, if growing hydroponically

Let’s take a closer look at how to get your crop started step-by-step.

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Step 1: Choose a Lettuce Variety

To set yourself up for success, choose the right type of lettuce for your indoor growing conditions. There are two varieties you can sprout indoors:

  • Head lettuce – Familiar types of head lettuce include iceberg lettuce, romaine lettuce, and butterhead lettuce.
  • Leaf lettuce – Leaf lettuce includes green leaf, red leaf, arugula, and mesclun, among others.2 Leaf lettuce requires less space per plant and less light. It’s often the best choice for growing indoors.

Step 2: Choose a Location

Lettuce has lower light requirements than other vegetables, but you’ll still need a location that gets plenty of sunlight, such as a south-facing room or windowsill. Here are some tips on lettuce light requirements:

  • Lettuce needs at least 6 hours of sunlight per day, and more is better3
  • Most indoor gardeners find it necessary to use a grow light to provide sufficient full-spectrum light4

Step 3: Decide On Your Growing Method

Growing lettuce indoors can be done either in soil or in a hydroponic system like the AeroGarden:

  • Hydroponic – Many home hydroponic garden systems will include everything you need: seed pods, grow lights, nutrient solution, and growing trays. Hydroponic growing systems are the best option for those who want a compact solution with little mess. Lettuce plants grown hydroponically are also ready for harvest up to 30-50% sooner than soil-grown plants.5
  • Soil – For this method, you’ll need seeds, a seed tray or other shallow containers, and a good lettuce seed starting mix. Growing in soil may be better for those with large amounts of vacant indoor space.

Step 4: Plant Your Seeds

When growing your seeds in an AeroGarden, just place your seed pods in the tray, add water, and turn on the grow light. Top up the water and add plant food according to the instructions for your garden.

To start seeds in the soil, follow these steps:6

  1. Fill seed trays with a seed starting mix and moisten the soil well.
  2. Then cover with a very light layer of soil. Don’t bury seeds deeply—about ⅛ of an inch of potting soil mix is plenty.
  3. Place in a warm, sunny location.
  4. Mist regularly to keep soil from drying out, and check daily for sprouts.

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Step 5: Watch Your Seedlings Grow

Seeds should sprout within 7 to 14 days with soil and 1-4 days in an AeroGarden. Once your lettuce seedlings have appeared, follow these tips:

  • Spacing – When your seedlings are around two inches tall, thin them out to one seedling per inch.
  • Water – Keep soil moist but not wet. In a hydroponic system, check that the water temperature stays consistent and make sure roots never dry out.
  • Light – South- or west-facing windows are ideal. Place grow lights about 6 inches above seedlings and leave them on for about 14 hours per day.7

Step 6: Harvest Your Crop

You can harvest lettuce starting in just 3 weeks and grow fully mature lettuce in just 4 weeks with an AeroGarden. Leaf lettuce is ready for harvest when the leaves are about 4 inches tall. To get the most from your crop, continue harvesting lettuce leaves as they mature.

Leaf lettuce can usually be harvested several times, and head lettuce will sometimes form another head from the stem.

Troubleshooting Your Lettuce Crop: Bolting

The lettuce plant is relatively easy to grow indoors, but bolting is a common problem when growing indoors. When lettuce is stressed, it flowers and goes to seed. This can be caused by high temperatures or too little water. Make sure you’re keeping soil moist. In hydroponic systems, check that the water isn’t too warm.

Farm-Fresh Greens Meet Countertop Convenience With AeroGarden

Growing lettuce indoors is a rewarding (and delicious) hobby, and in the end, you’ll have the fixings for a fresh, crunchy salad bowl or flavorful lettuce wrap ready to enjoy anytime. There’s no better way to get the whole family excited about eating their veggies than by watching them grow from seed!

With an AeroGarden, growing your own greens indoors is easy, clean, and convenient. AeroGarden takes the mystery out of growing fresh vegetables. All you need is water and plant food! Your AeroGarden will tell you exactly when to add water and plant food so you can enjoy a steady supply of healthy, fresh lettuce every month—no greenhouse necessary.


Sources:

1International Journal of Environmental Research and Public Health. Comparison of land, water, and energy requirements of lettuce grown using hydroponic vs. conventional agricultural methods. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4483736/

2The Kitchn. How well do you know your salad greens? https://www.thekitchn.com/types-of-lettuce-explainer-23312912

3University of Saskatchewan College of Agriculture and Bioresources. Hydroponic lettuce. https://gardening.usask.ca/articles-and-lists/articles-indoor-growing/hydroponic-lettuce.php

4, 6, 7Bob Vila. How to grow lettuce indoors for fresh salad greens year round. https://www.bobvila.com/articles/how-to-grow-lettuce-indoors/

5University of Illinois Extension. Home hydroponics. https://extension.illinois.edu/sites/default/files/illinois_extension_hydroponics_handouts.pdf

SF Gate. How to grow lettuce using hydroponics. https://homeguides.sfgate.com/grow-lettuce-using-hydroponics-69112.html