It's easy to grow leaf lettuce in plastic reusable grocery bags, which can be purchased at most markets for a dollar or so. These flat-bottomed bags can be also used to grow other vegetables and flowers. A leafy vegetable container of a variety of lettuces, spinach, and chard makes for a delightful miniature edible garden. Even some root vegetables, such as carrots, beets, and even potatoes can grow successfully in reusable grocery bags.
Leaf lettuce is a great container gardening vegetable because its short roots mean it can grow anywhere that has good drainage―even a shallow container. However, lettuce likes to be kept moist, and it is easier to keep your plants moist in a deeper container that holds more soil. An upright reusable grocery bag fits the bill perfectly. One advantage of a grocery-bag garden is that it is light and can easily be moved around a deck or patio to take advantage of sun patterns.
You can grow leaf lettuce from seed or from purchased seedlings, which are usually inexpensive. Plastic grocery bags are not well-suited for head lettuce, however, since the plants can be quite large and the bag becomes top-heavy with the weight. Start with a sunny spot, but one that isn’t too hot. Most leaf lettuce likes cooler temperatures, although you can find some varieties that are somewhat heat-tolerant (Black Seeded Simpson, Simpson Elite, Green Star, or Tropicana, to name a few).
Equipment / Tools
- Utility knife
- Garden gloves
- Reusable plastic grocery bag
- Potting soil
- Leaf lettuce seedlings
- Additional vegetables, herbs, and flowers (as desired)
- Plastic window screening (optional)
Cut Drainage Holes
The first step is to cut holes in the bottom of your bag. Don’t be shy―cut a bunch. Drainage is key since lettuce doesn't respond well to sitting in soggy soil.
If you wish, add a layer of window screening over the bottom of the bag to prevent potting mix from falling through the holes. This is most important if you will be moving your container around. To measure the screen, put the bag on top of the screening and then cut around the outline of the bag. The piece of screen doesn’t have to be sized perfectly―just big enough to cover the holes. You can also use newspaper or coffee filters to cover the holes.
Add Potting Mix
Add a general-purpose potting mix to your vegetable container garden up to about 1 inch from the top of the bag. Pick the bag up by the handles and gently tap it on the ground a few times to help settle the soil. Add more soil if you need to.
Consider using an organic potting soil that doesn’t have fertilizer already mixed in so you can manage the supplements yourself. As with any container garden, always use a commercial potting mix, not ordinary garden soil. Potting mix is a sterile concoction, without the pathogens found in garden soil. And it will be blended with peat moss or other organic materials that hold moisture better than ordinary garden soil.
If your potting soil doesn’t have fertilizer already added, mix in a slow-release, high-nitrogen fertilizer to the potting mix, following the label recommendations for quantity. Organic fertilizers are a good choice since they do not burn plants the way that synthetic fertilizers can. High-nitrogen fertilizers are the best choice for leafy vegetables such as lettuce since nitrogen stimulates green leaf growth. Make sure to blend in the fertilizer thoroughly.
Separate the Lettuce Seedlings
Many container garden plants come in a plastic nursery pack with four or six cells, and sometimes it can be a bit tricky to get the plants out without damaging them. Try turning the pack upside down, then gently squeezing or pressing the bottom and sides of each cell until the plants slide out. If you have to pull, don’t pull on the plant stem, which is delicate; instead, grab the soil plug and pull on that.
If the lettuce is root bound, gently tear the roots apart to prevent them from growing in a circle and eventually strangling the plants.
Plant the Lettuce
Dig a hole in the potting soil deep enough to allow the seeding to sit at the same level as it was in its nursery container. Don't plant too deeply. Set each seedling in its hole and pack the soil gently around the base.
Because lettuce has a quick growing season, you can plant lettuce seedlings fairly close together. This not only provides you with more lettuce, but it also makes the container look full and bountiful. A typical reusable grocery back can hold as many as eight lettuce plants or a combination of lettuce and other leafy vegetables.
When you harvest, begin by picking off the outside leaves, which keeps the container garden from getting too crowded.
Immediately after planting, water generously using a garden hose on a gentle spray or a watering can with a rose attachment. Keep watering until the water runs out the bottom of the bag.
As your container garden grows, check the soil at least once a day to determine its moisture level. To check, stick your finger up to the second knuckle. If the soil is dry at your fingertip, then it's time to water again until the water begins to run out of the bottom of the bag. It is better to give plants a good soaking less often than to give them frequent small sips.
How often you should water depends on the kind of potting soil you used, and how dry and hot the weather is. If it's windy, your plants will also dry out more quickly. In most cases, the container will need watering at least twice a week, and in very hot, dry weather, daily watering may be needed.
Care for Your Vegetable Container Garden
To care for lettuce plants, make sure that they don’t get too hot, and keep the soil moist by not soggy. Feed lettuce regularly with a liquid, high-nitrogen fertilizer, such as diluted fish emulsion.
Begin harvesting lettuce as soon as the leaves are sufficient in size. You can pick the leaves of leaf lettuce from the outside, letting the inside leaves continue to grow. You can also cut off the whole plant about an inch above the soil and let it re-grow.
Lettuce may start to slow down in the hottest months of the summer. Some people like to plant another crop with fresh seeds in the late summer for fall harvest. Or, you can change to kale, which is a good cool-weather vegetable that will produce up through the first frosts of early winter.