Fresh salad greens all year round? Yes please!
Instead of planting lettuce in your garden, growing lettuce in a bag allows you to plant it wherever, whenever.
Grow bags can be used outdoors or indoors in every climate zone.
Here’s everything you need to know about how to grow lettuce in a grow bag!
Can You Plant Lettuce in a Grow Bag?
Lettuce does very well in grow bags since it doesn’t need a lot of space to grow.
If you give the lettuce plant enough space for its roots, it will grow well in a bag. In fact, a grow bag can actually be better than other container types since it will allow for healthier root growth, leading to thicker foliage.
Related: What Can You Grow in a Grow Bag?
Choosing Your Lettuce Variety
There are 4 main categories of lettuce, with what feels like an infinite number of varieties in each category.
The good news is that most varieties of lettuce grow perfectly well in grow bags, whether you plant them indoors or outdoors. Some varieties are a bit trickier than others, but as long as you get the conditions right, the lettuce will thrive.
With that in mind, here are a few notes about the most common types of lettuce in each category and tips to grow them in a grow bag.
Leaf Lettuce (Red, green, oak)
About: Easy to grow with many different varieties for hot, cold, and neutral climates. Large leaves with defined spines and long stems.
Great for: fresh salads, garnishing, sandwich filling
About: Romaine lettuce varieties are the most nutrient-rich varieties of lettuce. Usually darker in color with a strong spine.
Great for: grilling, steaming, Caesar salad
About: Soft lettuce with large leaves, mild flavor, and a solid crunch.
Great for: lettuce wraps, sandwich/burger toppings
Crisphead Lettuce (Iceberg)
About: Head lettuce with crunchy leaves and a very mild flavor. One of the trickier varieties to grow, crisphead lettuce is commonly used by restaurants.
Great for: fresh salads, sandwich filling, shredded lettuce
Conditions Lettuce Needs to Grow
Lettuce favors cooler weather and consistent watering, but there’s plenty of wiggle room. You don’t have to get everything exactly right, so even beginners can manage to grow it well.
Here’s a rundown of the temperature, moisture, and sunlight preferences for growing lettuce in a grow bag.
Generally speaking, lettuce doesn’t grow well in the heat. Heat causes lettuce to bolt to seed, meaning it will skip a lot of the leaf-growing phase and jump straight to flowering and seeding. When this happens, you won’t get as many leaves to harvest and the leaves you do get might be bitter.
The best temperature range for lettuce is between 55°-70° F (12°-21° C), with 60°-65° F (15°-18° C) being the ideal range.
Lettuce can endure some frost, but heavy frost and freezing will destroy the plants. It can also tolerate a handful of short heat spikes before bolting to seed.
In temperate zones, the ideal time to grow lettuce is usually spring or fall. In hotter areas, winter may be the best season, especially if your area doesn’t experience freezing at any point over the winter. For colder climates, late spring, summer, and early autumn are likely the best times to plant lettuce.
Note: There are varieties of lettuce that are adapted to different climates, so you can find a few varieties that work well in higher heat or colder temps as well.
Lettuce likes a lot of moisture. It’s best to keep the soil moist, but not wet. If the soil dries out too often, the plant can get stressed and damaged.
Monitor the soil and water any time it begins to dry. This might mean watering once a day, especially if the weather is starting to heat up or if you live in a less humid climate.
Since grow bags dry out more quickly than other containers, you don’t have to worry about overwatering. It’s probably a good idea to water your lettuce daily unless the soil is already wet to the touch.
Lettuce has a tenuous relationship with sunlight. Because it doesn’t like high heat, it usually won’t do as well in full sunlight. Partial sunlight is best for lettuce.
As a rule of thumb, you should base the sunlight level for your lettuce on the temperature outside. The hotter it is, the less direct sunlight your lettuce will need. The colder it is, the more sunlight it needs.
In tropical, subtropical, desert, or other sunny climates, your lettuce will need more shade with limited direct sunlight. Protect it from harsh afternoon sun in favor of softer morning and late afternoon sun.
If you’re growing your lettuce indoors, keep it in a window where it will get some direct light, especially in the morning.
How to Plant Lettuce in a Grow Bag
Setting up your grow bag of lettuce is simple. Once you choose a bag, all you need to do is add the right soil mixture and plant your seeds.
Here’s how to do it.
Picking the Right Grow Bag for Lettuce
You can use any type of grow bag for lettuce. The size matters more than the material or shape.
Grow bags for lettuce should be around 6 inches deep.
Each separate lettuce plant needs between 1-3 gallons of soil, depending on the variety.
You can plant multiple lettuce plants in the same bag, even if they’re not the same variety. Plant the seeds a few inches apart so the roots have a little bit of breathing room. Before you reuse any grow bags you already have, make sure to wash them well.
If you’re looking for a larger grow bag, find a shallow one that’s wider instead of deeper. If you use a deep bag, put an appropriate filler in the bottom so you can use less growing medium and avoid any problems with compacting the soil.
Speaking of soil…
Adding the Soil
Lettuce thrives in soil that’s loose and well-draining.
An easy way to get this type of soil is to take regular garden soil and add compost or another type of organic fertilizer. This works with any texture of garden soil, whether it’s on the sandy side or harder like clay soil.
You can use bagged potting soil as a base as well, but you’ll need to add nutrients to it in order for your lettuce to grow well. Potting soil has a great texture and is completely sterile, it just lacks the nutrients you’d find in regular garden soil or compost.
Even if your soil already has great texture, add some balanced fertilizer or compost anyway to it to help with lettuce growth.
Growing lettuce from seed is simple. You can plant the seeds directly into the soil 1-3 inches down, or you can germinate them first in water before planting.
For indoor lettuce growing, both methods work well. If you’re placing your grow bags outside, hot weather can delay germination, so you may want to plan around the heat.
Germinating lettuce seeds indoors
To germinate lettuce seeds indoors, just place them in a dish with a tiny bit of fresh water. Use just enough to get the seeds wet without having them fully submerged or floating. Allow them to sit in the water for a day before planting to soften to seeds and begin germination.
You can also wrap them with a damp paper towel for a similar effect. Place the paper towel away from direct light or heat sources.
After the seeds are germinated, plant them into your soil, and voila! You’re ready to go.
If you’re putting seeds directly in the soil to germinate, get your lettuce grow bag set up wherever you want it and use your finger or a skinny tool to create small holes around 1-3 inches deep.
Plant 1 seed into each hole, if your seeds are fresh. If the seeds are more than 1 year old, you can plant 2-3 in each hole to ensure at least one will sprout. Thin out extra plants as they grow.
How to Care for Lettuce
When you’re growing lettuce in a bag, your main consideration is watering and pest control.
Beyond that, there are some things you can do to promote a good harvest and enjoy your lettuce for longer.
With grow bags, overwatering isn’t really a concern. Because they drain water very effectively, drying out is the bigger problem for lettuce.
Water your grow bag daily to keep the soil moist, not wet.
If watering daily is keeping the soil too wet, cut back to watering when the soil begins to dry out.
Lettuce plants suffer from stress if the soil dries out too often or too much while they’re growing. Since the leaves get bitter and don’t grow well when the plant is stressed, you want to avoid that as much as possible by watering consistently.
Unfortunately, you’re not the only one who enjoys fresh lettuce leaves. There are a few very persistent pests that will probably come after your lettuce plants as well, even if you’re growing them indoors.
The most common pests affecting lettuce include:
- Snails & slugs
While less common indoors, slugs and snails often go after lettuce grown outdoors. You can help manage them by keeping your growing area free of debris, removing any you find around your garden, spreading ash or egg shells around your grow bags, or placing shallow containers with beer around your garden at night to draw out and drown the slugs.
Although tiny, aphids can cause a lot of damage to lettuce as it grows. They spread quickly and the more there are, the more your plant is at risk of fungal infections and disease. Aphids can be controlled well in a home garden by using insecticidal soaps or neem oil on the leaves.
Similarly to slugs and snails, caterpillars wreak havoc on lettuce leaves, especially new growth. Cabbage loopers are the worst offenders. You can pick caterpillars off manually if you have a small enough crop of lettuce or use a gentle spray of neem oil, insecticidal soap, or lemon juice/vinegar to get rid of them. It’s best to remove caterpillars before they can establish any type of nest since the larvae spread rapidly.
- Leaf miners
Leaf miners lay their eggs on the leaves of your lettuce. When hatched, their burrow around the leaf, leaving visible trails around the leaf. Get rid of leaf miners by removing the section of the leaf where they are burrowing or using two fingers to squish the burrowed area from both sides.
There are other pests that affect lettuce. However, these are the most common pests you’ll encounter when you’re growing lettuce in a grow bag or other container type.
The most important thing is to give your plants a quick check whenever you water them. If you see any pests, you can deal with them immediately before they get out of control.
If you put fertilizer or compost in your soil when you’re planting lettuce seeds, you won’t need to do much for a while.
Once your lettuce heads or leaves are ready to begin harvesting, you can fertilize again as often as every 2 weeks, or every 3-4 weeks, with a small layer of compost or a balanced fertilizer on top of the soil. This is going to encourage continuous, healthy leaf growth.
Both leaf lettuce and head lettuce can be harvested without killing the plant itself. You can harvest them multiple times before needing to replant them.
Use a sharp knife or pair of scissors to harvest individual leaves.
When leaves are large enough to eat, harvest them individually from the outside in. Don’t remove the new leaves from the middle.
Cut leaves as low as possible on the stem without disturbing the base.
Harvest a lettuce head all at once with a sharp knife, shears, or large scissors.
Cut the lettuce at the base of the leaves. If you want the head to regrow, leave around 1 inch of growth above the base. The head will regrow, although it will not be as large as the first growth.
Once your plants are exhausted, you can remove them and replant fresh seeds. Leaves will eventually become bitter as the plant gets closer to seeding.
Regrowing Lettuce Stems
Did you know that lettuce can be regrown even after it’s harvested?
Whether you harvest lettuce leaves or heads, they can regrow if you leave enough of the stem and roots.
The key is to avoid damaging the base of the lettuce while you harvest. The base is where all new leaves grow, so as long as it’s healthy there should be some space for new leaves.
Lettuce can grow back endlessly until it dies or starts producing poor-quality leaves and seeding stems. Keep fertilizing the soil regularly so the plants have all the nutrients needed to regrow their leaves.
Lettuce is a wonderful addition to your grow bag garden. It can be grown indoors or outdoors by beginners and more experienced growers.
Enjoy fresh greens all year. Try planting your own grow bag of lettuce!
Want to grow another kitchen staple while you’re at it?
Check out our guide to growing potatoes in a grow bag!