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How To Grow Lettuce Indoors

Lettuce is a crop anyone can grow themselves at home. It is among the easiest plants to grow indoors or outside in a garden. To grow lettuce indoors, there is a simple process to follow:

  1. Decide on a good location for your indoor garden.
  2. Select a growing method and containers. 
  3. Choose which type and variety of lettuce to grow. 
  4. Sow lettuce seeds.
  5. Care for your indoor lettuce and harvest within as little as 4-6 weeks. 

Read on for a little more information about each of these steps, to help you start to grow lettuce indoors, wherever you live. 

Choosing Where to Grow Lettuce Indoors

How To Grow Lettuce Indoors

One of the keys to success in an indoor lettuce garden lies in finding the right location – one that is well suited to growing lettuce indoors. 

A good place to grow salad indoors is a sunny windowsill, though other light, bright locations within your home can also work well. 

If you have a location that receives light from the south, that will be ideal as a location with a southern aspect will get the most light (in the northern hemisphere). Lettuce will do best in a location with 8-12 hours of natural sunlight each day. 

Where this is not possible, and in winter when daylight hours can be short in northern latitudes, grow lights might be needed to grow lettuce. In most cases, however, you don’t need any special equipment to grow lettuce indoors. 

Growing Method and Container Options

To grow lettuce indoors, there are several options you might use. You can:

  • Grow lettuce as micro-greens, harvesting while the leaves are still very small. 
  • Grow baby-leaf lettuce, harvesting between around 4 and 6 weeks. 
  • Grow full heads of lettuce, harvesting at maturity. 

The first two options are the easiest choices and the middle option is the most common. Growing lettuce indoors to harvest at maturity will take up a lot more space. However, it is possible and allows you to grow lettuces that are not the typical cut-and-come-again loose leaf types. 

Which of the above options you select will determine the best growing method for you. 

Most commonly, lettuce is grown in potting soil/ compost in pots or other containers. However, hydroponic growing (growing in water rather than soil) is also possible with micro-greens or baby-leaf lettuce. 

As a leafy crop, lettuce is well-suited to hydroponic growing and other related growing techniques. And growing in water (especially as part of a small-scale indoor aquaponics system) is a water-wise, sustainable, and eco-friendly choice. 

If you grow in potting mix, a peat-free option should be chosen. Any peat-free multipurpose potting mix or a homemade alternative will work well. Your container can be a basic pot, or a more elaborate container option, such as a window box or a vertical garden. 

If you grow lettuce in water, you can choose from several different methods. 

For example, you might set up a simple raft above a receptacle filled with water, so the lettuce roots can dangle down into the water. 

Or you could create a more elaborate system of gutters and piping or another more complex hydroponic or aquaponic system. In an aquaponic system, you will grow fish as well as growing plants – growing even more food indoors. Lettuce grows extremely well in such a system. 

Selecting a Lettuce Type and Variety

As well as deciding on a growing method and working out which container you will choose to grow lettuce indoors, you should also consider which type and variety of lettuce to grow. 

Loose leaf lettuce varieties are the easiest to grow indoors and are the best choice for beginners. More experienced growers might also consider cos lettuce, romaine lettuces, etc.. headed iceberg types will be the most challenging to grow indoors. 

Some varieties are particularly bred to be harvested at an early stage of growth, so these are commonly referred to as baby leaf varieties. Pick some baby leaf, loose leaf types and you will enjoy a harvest in next to no time, with very little work and effort on your part. 

Sowing Lettuce Seeds

Once you know which lettuce you will grow indoors, and where and how you will grow it, you can source and sow your lettuce seeds. 

Lettuce seeds will germinate best when sown at temperatures between 16 and 20 degrees Celsius and not higher than 21 degrees Celsius. 

Place the lettuce seeds on a moist yet free-draining potting mix and cover lightly with the same growing medium. They must only be covered very lightly because the seeds need light to germinate. 

The seeds should germinate within a week in most cases. It is best to sow a small number of seeds every 2 weeks to get a continual supply of fresh lettuce leaves from your indoor garden. This is better than sowing lots all at once and ending up with lettuce that you cannot eat. 

Care and Harvesting when Growing Lettuce Indoors

Once the lettuce seeds germinate your lettuce will sprout and start to grow. Until harvesting, all you need to do is keep the lettuce seedlings well watered. But take care not to overwater and make sure excess water can drain away. 

With cut-and-come-again lettuce, you can simply snip off leaves from the clumps as required, or use scissors to harvest the lot. The plants should regrow new leaves a couple of times for further harvests before they are discarded. 

With lettuces that you want to grow on to maturity, you may need to thin out your seedlings as they grow. But always remember that these thinned little lettuces can also be added to your salads. 

Lettuce when fresh is a wonderful addition to your diet, but it won’t last long. Most of the time, whenever you want to harvest lettuces grown indoors, you should simply cut off the leaves you wish to take when you need them.