Nothing completes a sandwich or a burger quite like a fresh, crisp lettuce leaf. I mean, without its friend in the middle, a BLT gets pretty sad, indeed. And though (if we are being honest) most people tolerate a salad moreso than truly enjoy it, there is something about using the freshest possible lettuce—the fully-grown edibles you have grown from tiny little lettuce seeds—that makes the experience much more enjoyable. But what about when the weather outside turns frightful, uninhabitable by your favorite produce? Oh, the horror! However, there is no need to fret. After all, growing lettuce indoors is generally pretty easy and is usually successful even if your thumb is only tinged with green.
Below, you can find all the information you need to succeed while growing lettuce indoors.
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Find a Growing Space
First of all, you need to decide the best place for growing lettuce indoors. Generally speaking, a south-facing, large window is best. No matter what, though, you want to find a window space that allows for 12 hours of bright light a day. When the lettuce seeds are first planted, you want 14-16 hours of light.
If you are thinking that this arrangement is impossible in your living space, have no fear. Indoor grow lights are here! Indoor grow lights (or a grow lamp) help provide light that may not be as readily available during the winter months. They can also help add some warmth to the soil that contains the lettuce seeds, which will aid their germination and growth. After all, the best temperature for soil when you are growing lettuce indoors is 70 to 75 degrees.
Of course, often people wonder which are the best grow lights. As with many questions, there is not a one-size-fits-all answer. Many people use a fluorescent light fixture, especially if they have a pretty large growing area. If you have a smaller area (or if you prefer a more portable, easier-to-manage option) a grow lamp or a bulb that screws into your existing fixtures may be more appropriate. One more possibility exists, which is to install a more decorative light fixture that doubles as a grow lamp.
Decide Which Type of Lettuce You Want to Grow (Which May Not Be Lettuce at All!)
The second step to growing lettuce indoors is to find the right varieties. For the most part, you want to avoid head lettuce varieties. The reason for this is because heads of lettuce grow quite large, and most indoor gardens just do not have the space. Also, these lettuce varieties do not tend to fare as well indoors.
Instead, seek loose leaf types of lettuce, such as Grand Rapids, Green Ice, and Black-Seeded Simpson. These lettuce varieties grow in small sprigs without needing a lot of soil, so they work well in indoor gardens. Plus, you can use just a few leaves at a time, if that is all you need.
If you would like, you can choose to plant other leafy greens as well. Spinach, arugula, and mesclun, for example, often grow quite well indoors. These greens require the same growing conditions as lettuce, which is another reason to pair them together.
Use the Right Soil (Which May Not Be Soil at All!)
You have a few different options for planting if you are growing lettuce indoors. Most gardeners would not recommend traditional garden soil or potting soil. Those products are generally too coarse for planting lettuce seeds. Instead, you could use a seed starting potting mix. You could also use a soilless starting mix, using a combination of peat moss or coconut coir, vermiculite, and sand. Then, after the lettuce plants sprout, you can transplant them into traditional potting soil or simply keep going with a bit more fertilizer than typical.
Get a Good Container
Lettuce does not have a particularly deep root system. Therefore, when you are growing lettuce indoors, most containers work well. You just want to avoid a tiny container or one that is really large and deep. Indeed, some people even transform an old ice cream pail or plastic takeout container into a homemade indoor plant pot for lettuce. These work well because they are plastic, which we will explain more below. However, it is important that if you are creating your own indoor plant pot for lettuce, you add drainage holes in the bottom.
Indeed, one of the main qualities you want in a pot for lettuce is good drainage. Lettuce requires moist soil, but if your pot does not have proper drainage, the water will become excessive, and the plant(s) will be harmed.
When growing lettuce indoors, unlike many other plants, you need to consider the material of the pot. Many materials will heat up and wick away some of the moisture in the soil. Lettuce absorbs water and nutrients more than most plants, so plastic containers are the best choice.
Of course, an ice cream pail or old blueberry container works, but if you want a more unique planter for your lettuce, consider a 3D printed pot. They are made of a plant-based plastic called PLA. Therefore, they are perfect for your leafy greens (as long as they have drainage holes, of course). And, they look much more interesting than a traditional pot!
Plant Your Lettuce Seeds
Once all those important preliminary steps are taken, it is time to actually do the planting. You want to take your pot and fill it about ¾ of the way full with your soil or your soilless planting mixture. (Pro tip: Adding a little moisture during the process will make the soil even more ready to promote seed growth.) Then, place the lettuce seeds on top and cover them with another thin layer of soil, about ¼ to ½ of an inch. When starting seeds indoors, many gardeners cover the planter with plastic wrap to trap moisture and maintain high levels of humidity. Once the sprouts begin to shoot out of the soil, you can take off the wrap.
Ideally, lettuce plants are going to grow around 1” apart. So, you want to try to create distinct rows and columns if possible. However, lettuce seeds are small and can be hard to place perfectly. As a result, do not stress much about the placement of the seeds at this point. Once the seeds have germinated, you can always pull out some plants if they are growing too closely together. In fact, pulling a few seedlings away helps you remove ones that do not look as strong.
Give Your Plant Babies a Little TLC
After the planting, you are well on your way to growing lettuce indoors, but the work is not done yet. Though lettuce is pretty easy to care for, it does not grow itself—especially indoors! In fact, to help your plants be their absolute best, you need to monitor lettuce daily.
Water
Of course, lettuce’s most consistent need is the same as most plants: water. Lettuce does use a fair amount of water, so you will want to keep an eye on the growing medium you are using (the soil or the mixture mentioned above). Most home gardeners use a spray bottle with lettuce. This helps ensure that the lettuce is receiving moisture without being waterlogged. However, if the growing medium seems particularly dry (dry up to or past your first knuckle), it is okay to give a traditional soak as well. Just be sure that you have proper drainage in your pot so that the lettuce plant isn’t sitting in a pool of water; this will cause the lettuce to rot.
Fertilizer
Since lettuce and other leafy greens take in a lot of moisture, they also soak up a lot of nutrients. The problem is that the plants can then deplete the nutrients in the soil, which can stunt growth and even impact the taste of the final product. Therefore, you want to add fertilizer (this one is great for lettuce and very affordable!) before planting and at least once in the growing process. Just be sure to apply whatever fertilizer you use to the soil and not to the plant itself, which could hurt the leaves.
And More!
Other than that, just monitor the citizens of your indoor garden. If you see spindly plants, they need more light. Yellow leaves could be a sign of overwatering. If you see wilted leaves, your lettuce needs more water. Brown spots on the plants could mean bugs or a disease, or they could mean that the leaves are too close to a heat source or a drafty window. Though lettuce are hearty plants, they certainly can have their fair share of problems. So keep an eye on your crop while you are growing lettuce indoors and don’t be afraid to use a search engine to find the solutions.
Harvest
Most lettuce plants will be ready to harvest in about 4-7 weeks. However, really, you can begin to eat the leaves as soon as they have reached the desired height. You want to eat whatever you pick right away for maximum freshness. As a result, many people will pick some of their lettuce one day and let the rest grow for another week before they pick some more. This technique allows you to have the freshest, best-tasting lettuce for the longest amount of time.
One of lettuce’s many superpowers is its ability to grow back if harvested properly. Lettuce can often grow back within two weeks, though it is generally smaller and sweeter the second time around. And if your leafy greens don’t end up coming back, you can always start the process over again. After all, since lettuce goes from seed to harvest so fast, you can go through the cycle three times in most winters.
Eat Up
Of course, the last step is always the best. You get to enjoy the fruits (or in this case, vegetables) of your labor! And of course, when you know that every lettuce leaf you are consuming is because you are growing lettuce indoors, it just tastes that much better. Some might say it tastes like pride.
