It's easy to grow leaf lettuce in plastic reusable grocery bags, which can be inexpensively purchased at most markets. These flat-bottomed bags also can be used to grow other vegetables and flowers. Even some root vegetables, such as carrots and beets, 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 in a shallow container. However, lettuce likes to be kept moist, and it is easier to keep your plants moist in a deep container that holds more soil. So an upright reusable grocery bag fits the bill perfectly. One advantage of a grocery-bag garden is it's 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. But note that plastic grocery bags are not well-suited for head lettuce, as the plants can be quite large and the bag can become top-heavy with the weight. Start with a sunny spot. Most leaf lettuce likes mild temperatures, though you can find some varieties that are somewhat heat-tolerant (e.g., Black Seeded Simpson, Simpson Elite, Green Star, or Tropicana).
Equipment / Tools
- Utility knife
- Gardening gloves
- Garden hose or watering can
- 1 reusable plastic grocery bag
- All-purpose potting mix
- 8 leaf lettuce seedlings
- Plastic window screening (optional)
Cut Drainage Holes
Cut small drainage holes in the bottom of your bag. Don’t be shy―cut a bunch. Drainage is key because 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 it 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
Fill the bag with an all-purpose potting mix up to about 1 inch from the top of the bag. Pick up the bag by the handles, and gently tap it on the ground a few times to help settle the soil. Add more soil if necessary.
Consider using an organic potting soil that doesn’t have fertilizer already mixed in, so you can manage the supplements yourself. 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's 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, following label instructions. Organic fertilizers are a good choice, as they don't burn plants the way synthetic fertilizers can. High-nitrogen fertilizers are the best choice for leafy vegetables, such as lettuce, because nitrogen stimulates green leaf growth. Make sure to blend in the fertilizer thoroughly.
Separate the Lettuce Seedlings
Take your seedlings, and gently remove them from their nursery containers. If you have to pull them out, 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, meaning it has dense and tightly packed roots, gently tear apart the roots to prevent them from growing in a circle and eventually strangling the plant.
Plant the Lettuce
Dig holes in the potting soil deep enough to allow each seedling to sit at the same level as it was in its nursery container. Don't plant too deeply. Set each seedling in a hole, and pack the soil gently around the base.
Because lettuce has a quick growing season, you can plant the seedlings fairly close together without having to worry about the plants outcompeting each other. A typical reusable grocery back can hold as many as eight lettuce plants or a combination of lettuce and other plants.
Immediately after planting, water generously using a garden hose on a gentle spray or a watering can. 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 into the soil up to the second knuckle. If the soil is dry at your fingertip, then it's time to water again until the water runs out of the bottom of the bag. It is better to give lettuce plants a good soaking less often than to give them frequent small sips.
How often you will have to water depends on the kind of potting soil you used and how dry and hot the weather is. Also, if it's windy, your plants will 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 might be necessary.
Care for Your Vegetable Container Garden
To care for lettuce plants, make sure they don’t get too hot and keep the soil moist but not soggy. Feed lettuce regularly with a liquid, high-nitrogen fertilizer, such as diluted fish emulsion, following label instructions.
Begin harvesting lettuce as soon as the leaves are sufficient in size. You can pick off the outer leaves, letting the inside leaves continue to grow. Or you can cut off the whole plant about an inch above the soil and let it regrow.