Tony O’Neill, gardener and author of the popular “Composting Masterclass” and “Your First Vegetable Garden,” combines lifelong passion and expert knowledge to simplify the art of gardening. His mission? Helping you cultivate a thriving garden.
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Container gardening is a popular option for growing lettuce, especially if space is premium. It is an excellent way of having greens readily available.
Containers provide color, and their proximity to a workspace makes caring for them more manageable. Placed on a windowsill, patio, deck, or balcony, or where growing conditions are favorable, containers are ideal for growing lettuce and other salad greens.
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Early spring brings a sense of new beginnings, peach trees emerging from dormancy, asparagus tips poking through the soil, and the ideal time to start lettuce plants. There are few things as satisfying as having access to homegrown tender lettuce.
Many lettuce plants and greens thrive in the cool spring weather. We will explore the numerous benefits of growing lettuce in containers, how easy it is to grow, and seven of the best varieties for growing in pots.
But first, let’s explore the best types and cultivars and why some lettuce varieties are more suitable for growing this cool-weather crop. I share about picking leaf lettuce (outer leaves) and how easily lettuce grows.
7 Cultivar Choices to Grow Lettuce in Containers
Several factors determine your choice of lettuce plants for growing lettuce in containers. You need to be practical about the time to care for a plant, what types of lettuce you prefer, and how patient you are.
Clearing the Confusion Regarding Lettuce Types
The line differentiating types of lettuce is often blurred as seed producers strive for the best product, one that is easy to grow yet offers the consumer everything they need from lettuce.
Traditionally, there are five lettuce groups, though some advisers differentiate between seven types. Below is a list of the seven and a cultivar example from each one – ideal for lettuce in pots:
- Bibb lettuce – Newham
- Boston Lettuce – Nancy
- Butterhead Lettuce – Harmony
- Crisp Lettuce – Muir
- Iceberg – Mighty Joe
- Leaf Lettuce – Red Express
- Romaine Lettuce (Coss) – Coastal Star
1. Bibb Lettuce – Newham
Bibb lettuce is a variation of butterhead lettuce known for its mild flavor and tender texture. It is a loose-leaf type of lettuce with soft, pale green leaves that form a head.
The leaves are often frilled and have an almost buttery texture. Bibb lettuce is popular in sandwiches, salads, and wraps and is an excellent source of vitamins A and C, calcium, iron, and fiber.
The Newham lettuce is an heirloom variety that originated in Newham, England. It is an open-pollinated Bibb variety and grows as a rosette of leaves. The leaves are typically green with a red tinge and have a sweet, buttery flavor.
Newham has a good shelf life and can be stored in the refrigerator for up to one week.
2. Boston Lettuce – Nancy
Boston lettuce is a type of butterhead that belongs to the same species as iceberg lettuce but is much softer in texture and has a milder, slightly sweeter taste.
Its leaves are round, light green, and loosely formed with a buttery texture. It is best enjoyed in salads or as a wrap for sandwiches. It is also commonly used in recipes such as salads and sandwiches.
Nancy lettuce is a variety of butterheads with a small, tightly-packed head and a mild flavor. It is rich in vitamins A, C, and K and is a good source of dietary fiber.
You can start harvesting lettuce leaves 25 days after planting, with the prospect of continually harvesting outer leaves for an additional 30 days.
3. Butterhead Lettuce – Harmony
Harmony lettuce is a high-yielding, heat-tolerant variety of butterhead lettuce that is often grown during summer. It has a soft, buttery texture and is known for its sweet and mild flavor.
The leaves are bright green and frilly, and the heads are dense and compact. The lettuce has no long shelf life, so it is best harvested and consumed within a few days of being picked.
Harmony lettuce is perfect for salads and sandwiches or can be cooked and added to soups and stews.
4. Crisp Lettuce – Muir
Crisp lettuce has a crunchy texture and a mild, slightly sweet flavor. It is often used in salads or as a garnish. It can also be used in sandwiches, wraps, and tacos.
Crisp lettuce is famous for its crunchy texture and mild flavor, making it an excellent choice for salads and other dishes. It is usually light green and has a slightly sweet taste.
Muir lettuce is a variety of crisphead lettuce developed in California in the early 1970s. It has a crisp texture and a mild, sweet flavor. It is a popular choice for salads and other dishes.
5. Iceberg Lettuce – Mighty Joe
Mighty Joe lettuce is a variety of butterhead lettuce bred by the Dutch seed company Rijk Zwaan in 2012. It is characterized by large, round, frilly leaves, making it an attractive addition to salads and other dishes.
The leaves are a deep green color and are crunchy and sweet. It is slow to bolt, making it an excellent choice for home gardeners who want to enjoy a long harvest season.
It is also tolerant of high temperatures and humidity, making it an excellent choice for warmer climates. Its large leaves make it ideal for wraps, tacos, and sandwiches.
6 Leaf Lettuce – Red Express
Loose-leaf lettuce is a famous salad green, generally more tender than other types. It has a mild flavor and is often used in salads and sandwiches.
Because of its tenderness, keeping loose-leaf lettuce refrigerated and using it within a few days of harvesting is essential. Having lettuce plants indoors, especially loose-leaf lettuces will give you a constant supply throughout the growing season.
Staggered, succession planting keeps a constant supply up to a fall harvest. Grow lettuce in the shade, with partial sun exposure. Lettuce grows well in well-draining soil.
The Red Express lettuce is a bright red color known for its crisp, delicate flavor. The leaves are also very tender, and the plants are easy to grow. Red Express lettuce is a popular choice for salads and sandwiches.
7. Romaine Lettuce (Coss) – Coastal Star
Romaine lettuce has long, crisp leaves and a slightly bitter flavor. It is often used as a base for salads and can also be used in sandwiches, wraps, and other dishes.
Romaine lettuce is nutritional, containing vitamins A and C, folate, and potassium. It is a good option for lettuce in pots. Romaine lettuce can be enjoyed as a low calory option as part of a healthy diet.
Coastal Star lettuce is known for its classic buttery flavor. It is a large, semi-heading lettuce with light green, soft, broad leaves and a slightly sweet taste.
Coastal Start is a good source of vitamins A, C, and K, as well as manganese and folate. Its leaves are hardy and can last up to a week in the refrigerator.
Choosing a Lettuce Growing Container
Choose a tray, pot, or window box with a minimum diameter of 18 inches and a depth of 6 to 12 inches. Plants benefit from deeper pots since the soil doesn’t dry up as quickly, and the roots have more room to spread out.
You can use a self-watering container or stack one tray inside another to minimize leaks, but whatever material you use for the container must have drainage holes in the bottom.
Put in some high-quality potting soil; some soils are designed to hold onto water, which is very helpful in dry climates. Plants and soil in containers kept outside will lose more water and require a more substantial supply of soil moisture.
Soak plant pots in a solution of one part household bleach to nine parts water for at least 10 minutes, scrub with a stiff brush to remove soil and mineral deposits, and rinse well.
A Potting Soil Recipe for Growing Lettuce
While you may often be told that the best soil for containers is artificial or soilless media, I beg to differ. The benefits of including organic matter and microorganisms in your potting soil outweigh any risks gardeners speak of.
The Argument for Soilless
The main arguments for soilless pots are weight benefits (making it easy to move) and avoiding soil compaction. However, adding some mature compost boosts the cation exchange capacity and a plant’s resilience to infections and pests.
Also, lettuce plants want slightly acidic soil (a pH of 6.0 to 6.8), which inert materials can offer if not mixed with some peat moss.
A Perfect Potting Mix
While drainage is essential (offered by inert materials), growing lettuce in containers is more than merely avoiding root rot. We have to consider the entire plant, something that ensures moist soil and can manage a balanced fertilizer.
A 2:1:1 mix of inert material (pumice, perlite, or expanded shale), compost, and peat moss is a good quality soil mix.
Topsoil and regular garden soil compact too quickly in containers, cutting off the plant’s access to water and oxygen. While soil tends to compact in pots, artificial media is explicitly made for that purpose and won’t.
I know it sounds wasteful, but avoid reusing a soil mix where you grew a crop the previous year, as it may also be a breeding ground for disease.
Throw out the stale media and disinfect the container with a 10% bleach solution when the season is through. One cup of bleach to nine cups of water is all it takes to make the solution.
Growing Lettuce Plants
Growing lettuce is easy-peasy. Plant lettuce seeds in inert materials like perlite, covering the seeds in vermiculite. The seeds should be about a quarter inch (8 – 13mm) under ultra-light vermiculite.
Lettuce seeds need light to germinate, and lanting in organic soil increases seed pathogen risks. Keep the lettuce seeds consistently wet to avoid collapsing the process. Lettuce seeds germinate about a week after planting, depending on soil temperatures (60 – 70°F/15.5-21°C).
If you don’t have both vermiculite and perlite (or pumice), sow seeds the seeds in the perlite only and cover them lightly. Keep the soil moist, and consider using a heating mat if temperatures are low.
Transplant the lettuce seedlings, burying the roots only. Unlike tomatoes, lettuces don’t want any part of their stems underground. If you’re planting multiple lettuce seedlings in a pot, keep the spacing 12 inches (30 cm) apart uniformly.
Only transplant seedlings once any risk of frost has passed, hardening plants off by incrementally exposing them to their final destination (a couple of hours a day).
The Best Way to Germinate Lettuce Seeds
Lettuce seeds are prone to soil-borne infections. Heat-treating your lettuce seeds to warm water (118°F/47°C) for 30 minutes will help. Lettuce seed dormancy is a challenge to break, and the USDA has a whole study on the topic.
Breaking Seed Dormancy in Lettuce
Some specialists advise soaking the seed in water for 6 hours and then exposing it to diffused light at 73°F/23°C while others argue that presoaking the seed in water at 68°F/20°C for 2 hours was the best method of inducing germination.
FAQs for Growing Lettuce Indoors
In Closing
Early spring or mid-fall is the ideal time to plant lettuce in pots or in your garden. This cool-season crop does excellent throughout the year if you can keep the temperature low.
Planting lettuce is easy, but avoid sowing seed directly into the soil. Growing leaf lettuce in your kitchen can give you a constant supply of fresh lettuce, picking the outer leaves as the lettuce grows.
Clay pots filled to about an inch from the top are ideal. Shallow containers need more frequent watering, especially in a warm climate. You must keep the soil damp to keep plants healthy.