Many of us have a green thumb but no real garden space. Container gardens are an excellent way for almost anyone, including city dwellers, to grow a few herbs or greens on patios, decks, and balconies. If no outdoor space is available, even a sunny window can work. Because lettuce has shallow roots, it grows well in containers — and it’s one of the easiest vegetables to cultivate.
Growing your lettuce in pots also makes it easy to extend the growing season by planting lettuce indoors in early spring and transitioning plants to outdoor spaces when it’s warm enough. Likewise, you can move your lettuce plants inside in the fall when temperatures dip to extend the growing season.
Gathering Garden Supplies
Decide if you want to grow a loose-leaf lettuce variety or head lettuce. Loose-leaf varieties tend to be a bit more heat tolerant and you can harvest them more gradually. How long it takes for plants to reach maturity depends on the variety but tends to be between four and eight weeks. It is alright to harvest baby loose lettuce leaves, but harvesting lettuce too late can have its issues.
Make sure you use high-quality organic potting soil and, ideally, organic lettuce seeds. Your pots should be at least six inches deep and have a drainage hole in the bottom. The ideal containers depend a bit on the lettuce variety you grow because the necessary space will vary.
You can either direct sow your lettuce seeds in the pot or transplant seedlings into your pots. Purchasing seeds is typically more economical and reduces plastic container waste.
Establishing Your Lettuce Plants
Lettuce is a cool-weather crop, and it does have some sensitivity to summer heat. The ideal temperature for growing lettuce is between 60 and 65 degrees Fahrenheit. For a spring crop, sow your seeds after the chance of a hard frost has passed. For a fall crop, sow seeds four to six weeks before the last frost date in your location. Although your plants can tolerate a light frost, they will not do well with a hard freeze. If you are growing lettuce in the summer, partial shade is ideal. When cultivating it in the spring and fall, full sun is best.
It is essential to harden off the seedlings for a few days before moving them outside full time. This involves leaving the plants outdoors for several hours at a time but not in extreme sunlight for long periods or cold temperatures.
Ideally, your plants will get about six hours of sun. If adequate sunlight is an issue, consider moving the pots to give your lettuce plants more direct rays — you need to move the plants mid-day. Keep in mind that lettuce doesn’t like super intense sunlight for the entire day during the summer months.
If you do not have an outdoor spot for your lettuce plants, a sunny, south-facing window is a good backup option. If there isn’t such a spot, it is possible to supplement with a grow light.
Lettuce likes moist but not water-logged soil for growing. Too much water will make the plant unhealthy, so the trick is regularity but not drenching your lettuce. When growing in containers, your plants will need more frequent watering than they would if you were growing them in the ground.
It is time to harvest your crop when the leaves are formed but before the plants have bolted. This is when the plant shifts from putting energy into the leaves to creating flowers. Unfortunately, the lettuce turns bitter when this happens. Dry conditions and high temperatures encourage this, so keep an eye on the plants and harvest them before it bolts.
Now it is time to enjoy the harvest! Make a salad, use it as a garnish, or top your favorite sandwich with the freshest lettuce around.