Lettuce is a simple crop to grow and one that can be grown indoors highly successfully. It is a quick and easy-to-grow plant and it means that even novice gardeners or those without any outdoor space can enjoy the pleasures of homegrown lettuce.
There is a wide variety of lettuce types and all are suitable for growing indoors, though some are more advantageous than others. For example, loose-leaf types can offer you a really quick and regular harvest of leaves for salads and sandwiches.
Growing lettuce indoors is all about providing the right growing conditions, such as adequate light, temperature, water, and humidity. Get that right and it is even possible to grow lettuce indoors year-round.
Tips for growing lettuce indoors
Lettuce is a fast-growing vegetable, either from plants or seed, and one of the easiest vegetables to grow – it can be a really low-maintenance indoor crop. You can easily grow lettuce in pots on a windowsill for quick and easy tasty leaves.
Loose leaf varieties are best suited to growing indoors as they take up the least space of all the lettuce types, have a shorter growing period, and can be harvested multiple times. Those varieties can be ready to harvest in just a couple of weeks from germinating, even sooner if you crop smaller leaves. A superb option is the loose-leaf lettuce blend from Burpee, which contains five different varieties in the form of Black-Seeded Simpson, Lollo Rossa, Red Salad Bowl, Royal Oak Leaf and Salad Bowl. It offers different textures and colors for the windowsill and can be harvested quick. Lettuce types that form heads can take from 6-12 weeks to be ready to harvest.
Amber Noyes, a horticulturalist and editor of Gardening Chores, claims growing lettuce indoors ‘can be a breeze’ and it is ‘completely achievable’ to get fresh, homegrown lettuce on a windowsill.
‘The good news is that lettuce is one of the easiest and most rewarding veggies to grow indoors,' says Amber. ‘Better yet, there are numerous types and varieties to choose from, so you can experiment and find the ones that suit your taste buds and indoor conditions the best.
‘And that doesn't take into account the fact that growing lettuce indoors can be a fantastic learning experience for kids too. I've seen first-hand how introducing little ones to the joys of gardening can spark curiosity and a deep-rooted love for plants.’
Amber Noyes is a plant expert who has a master’s degree in horticulture from the University of California as well as a BS in Biology from the University of San Francisco. She brings experience from working on an organic farm, at farmers markets, and at a plant nursery.
How to grow lettuce indoors in 6 steps
If you are wondering whether it's hard to grow lettuce on a windowsill, then rest assured as the answer is it is very simple. You need only a few simple pieces of equipment to get you going and then a small amount of maintenance to keep the plants watered and looked after.
You can either buy small lettuce plants from a garden store to plant up into containers, or lettuces are simple to grow from seed and you can sow the crop directly into the pot. If you want to grow lettuce from seed or simply plant lettuce, here are six simple steps to follow:
- Choose a container with good drainage holes in the bottom.
- Fill the container with a high-quality potting mix, do not reuse garden soil in pots
- Sow your chosen lettuce seeds thinly on the surface, or plant your lettuces around six inches apart.
- Place the container on a windowsill with plenty of light, preferably south-facing.
- When judging when to water plants, be vigilant and keep the soil moist but not waterlogged.
- Start harvesting lettuce as soon as the leaves are big enough to eat.
You want to find a sunny windowsill in the home, for example a south-facing window will provide the best light levels for lettuce growing indoors. Ideally you want a spot that can provide at least six hours of sunlight a day at a temperature of 50˚F to 60˚F.
However, Annette Hird, an avid gardener at Easy Urban Gardens, warns that direct sunlight on hot summer days can potentially harm your plant. She says: ‘Lettuce can be grown on a bright windowsill as long as the plants don't get exposed to direct sunlight. Sun coming in through the glass can easily burn the plants. Especially in summer when the sun is hot. There's also the danger of the plants going to seed in summer if they're exposed to direct sunlight.’
Growing lettuce indoors under lights
Providing the adequate levels of sunlight is always key to growing lettuce indoors and even a south-facing windowsill may not always provide enough sunlight for the plants to thrive. This is especially true in the fall and winter months in many US hardiness zones.
If you do not have a spot where you can provide enough natural sunlight for the plants, then consider investing in artificial grow lights. These can supplement any natural light and prevent potential issues. One example of a good grow light for lettuces on a windowsill is the GYTF Halo Plant Grow Light available at Amazon that provides a full spectrum of light to indoor plants.
Without access to sufficient light, your lettuces are likely to become leggy and weak plants. Plants or seedlings become leggy because they are stretching to get to the light and it often results in them becoming long and straggly.
These leaves are not going to be good for cropping, so if you do have concerns about light levels, or want to grow lettuce indoors year-round, then a simple artificial lighting set-up can help ensure that plants grow healthy and you get a better lettuce harvest.
Best lettuce varieties for growing indoors
There are different types of lettuce to grow, including butterhead, crisphead, romaine and loose-leaf. It is a common thought that loose-leaf varieties are best suited to indoor growing, as they are quicker to grow, don't require as much space as head lettuce, and can provide more than one harvest.
Bob Flowerdew, gardening expert at Homes & Gardens, claims you can be ‘amazed’ at how much can be grown on a sunny windowsill but you do need to carefully consider which crops are selected. As well as lettuce, growing herbs indoors is highly popular, while you can even grow garlic indoors on a windowsill too.
He says: ‘Space is at a premium so it’s sensible to grow those things you really like most. Second, it’s most productive to grow those crops that can be cut and come again or picked regularly, and those that are quickest from seed.’
Loose-leaf varieties allow for multiple harvests, by simply snipping the outer leaves when needed, and are ready to harvest quickly. Smaller leaves can be ready to crop in as little as two weeks after germinating.
Bob Flowerdew is the organic expert for Amateur Gardening magazine in the UK. Every week he writes about a wide range of gardening tasks and offers advice on how to create a sustainble, eco-friendly garden. He has also written a wide range of books on organic gardening methods, all available on Amazon.
Can you grow heads of lettuce indoors?
While, as mentioned, loose-leaf varieties are regarded as best for indoor growing, it does not rule out choosing lettuce types that form heads. These types require extra care and will take longer to grow, but will successfully provide a harvest being grown on a sunny windowsill.
Amber Noyes recommends: ‘Butterhead types like Buttercrunch and Tom Thumb are also excellent choices for indoor growing due to their compact size and adaptability to container gardening.’
Can you grow lettuce indoors all year?
Lettuce can be grown indoors or on a windowsill all year round, however artificial grow lights are likely to be required to give them the levels they want during the winter months. They need at least six hours of sunlight a day and temperatures of at least 50˚F to grow happily indoors.
If you want to grow indoors year-round, then choose lettuce varieties with the terms such as ‘winter’ or ‘arctic’ in their name as they require the lowest light levels. As smaller plants require less light, you can also maximize any winter crop by harvesting leaves that are smaller in size rather than trying to grow plants to full size.
What is the best container for growing lettuce indoors?
Lettuces have a shallow root system so do not need a deep container to be grown in. The width is more important than the depth, you want it to be wide enough to contain your lettuce plants and no narrower than six inches wide. A small-to-medium-sized rectangular container is ideal for growing on a windowsill and will allow a short row of lettuces.
Make sure that any container has drainage holes in the base to allow excess water to escape, and remember to place something underneath the pot to catch that water – especially important when growing lettuce indoors on a windowsill. Forgetting about drainage is a common container gardening mistake and a key point you must consider, otherwise your plants can rot from moisture accumulating around the roots. Drainage holes are vital to put in a planter to aid drainage.
If you do not have a backyard kitchen garden or even space for a vegetable garden container, then that should not stop you from growing lettuce at home. Lettuce is one of the simplest crops to grow and it can be a really enjoyable experience for you and your family to grow, care for, and harvest homegrown lettuce from a windowsill. It is really simple to do and can be done on a budget. Once you taste those homegrown leaves, you will no longer want to go back to the limp and tasteless ones you get in a bag at the grocery store.
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Drew’s passion for gardening started with growing vegetables and salad in raised beds in a small urban terrace garden. He has gone on to work as a professional gardener in historic gardens across the UK and also specialise as a kitchen gardener growing vegetables, fruit, herbs, and cut flowers. That passion for growing extends to being an allotmenteer, garden blogger, and producing how-to gardening guides for websites. Drew was shortlisted in the New Talent of the Year award at the 2023 Garden Media Guild Awards.
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