Lettuce is the staple crop for vegetable gardens and can be used to make simple, elegant salads. Learn how to grow lettuce and how to prevent downy mildew.
You can grow your own vegetables whether you own your own home or live in an apartment. Author Karin Eliasson gives advice on growing over 100 vegetables as well as how to use them in the kitchen. In this excerpt taken from Greens! (Skyhorse Publishing, 2013) learn how to grow lettuce, from iceberg to romaine.
You can purchase this book at the MOTHER EARTH NEWS store: Greens!.
No meal is complete without a large and flavorful salad. Especially in summertime when we can freeze freshly harvested leaves. And you can vary a salad an infinite number of ways, add all kinds of vegetables, nuts, seeds, and fruit, but personally I think the most elegant salad is the simple leaf salad that is only leaves of different colors, flavors, and textures. With a good dressing as a flavor enhancer, it can become the absolute highlight of the dinner table.
Lettuce is a kitchen growth, and it has always been part of my vegetable garden. It is great because it is so easy to grow — you can grow it in a pot, balcony case, hotbed, or in the vegetable garden. Anyone can grow their own lettuce in summertime! With all of the lettuce varieties you can find today, you can also make a very decorative planting of lettuce and enjoy them for a long time. Multiple lettuces are made to harvest continuously and this way you can enjoy the same plant for a long time. This is especially true for leaf lettuce, but also certain head lettuce varieties.
Even though the selection of salads in the vegetable sections of our country’s stores have gotten a lot better over the last years, it is still a huge advantage to harvest your own. As with all vegetables, freshly harvested lettuce is crisper and more flavorful. Directly from the earth to the salad bowl, the shorter the time in between, the better. I always want my lettuce like after a dewy, fresh summer night, chockfull of leaf cells that break when you chew so that it sounds fresh and releases sweet, bitter, and fresh flavors.
In Sweden, we are accustomed to milder lettuce varieties, like the popular “butterhead” and loose-leaf salads, but I highly recommend cultivating a couple plants of the bitter chicory, such as radicchio. Blend in a few leaves and generously drizzle with dressing made with olive oil, lemon, and salt. You will be surprised by the flavors a simple leaf salad can offer.
In order to succeed in having a nice lettuce to harvest for the entirety of summer, it could be a good idea to sow some plants now and then. This way you will continuously keep a small family of lettuce plants on the stairs. Some that are almost done, some teenagers that are now ripening, and a few babies that still need a couple of weeks before their leaves are fully developed. If you end up with too many plants you can always eat the small-plants as well; they generally have a milder flavor, tender and tasty.
Lettuces are not demanding vegetables. Since we only want the leaves and no flower or fruit, everything that stimulates leaf growth is good for the plant. They need a lot of water and nitrogen to obtain a nice color and crispness. The greatest challenge might be managing to keep these plants to yourself. Snails, grasshoppers, woodlice, and all other small bugs love lettuce. But they rarely create enough trouble that it disturbs the joy of growing it.
Under the umbrella lettuce (Lactuca sativa) you find leaf lettuces, iceberg lettuce, head lettuces, and romaine—also called Cos lettuce. What separates leaf lettuce from the rest is that they grow in bouquets instead of heads. This makes it possible to pinch leaves off continually without ruining the plant. You can do this with the head lettuce as well, and first and foremost with romaine. In the beginning of the season you can carefully loosen a couple of the outer leaves, but when the lettuce finishes their heads, you should stop removing leaves and let them shape their heads in peace.
Preparing the Growing Site
Lettuce should grow in the sun or in half-shade. It is most important that the growth site is warm and sheltered from the wind. It grows in light and humus-rich soil that can hold warmth. Therefore, prepare the soil with rough sand, compost, and/or composted manure if you know that you have a muddy soil. If you grow in pots, use special soil for that purpose. It should contain quality peat that helps the soil keep its structure and airiness and prevents it from falling apart around the roots of the plants.
When? You can choose to either directly sow the lettuce or pre-cultivate them inside. Leaf lettuces develop quickly and are great to sow directly while certain head lettuces and iceberg lettuce take a while longer and may therefore benefit from pre-cultivation. The time it takes for the various kinds to develop is listed in the seed catalogues or the seed bag.
Expect to start sowing three to four weeks before you plan to set the plants in the ground. Lettuce seeds can grow at a temperature as low as 40°F (5°C). In other words, you can sow them early, also in a regular hotbed. Most lettuces endure cold nights, even a couple of nights below 30°F (0°C), so you can safely plant your lettuce early in summer and not harvest until late fall.
It is important to remember that lettuce seeds will not grow in overly high temperatures; 65°F (18°C) is the general limit. Anything under 65°F (18°C) is fine, but over that, the temperature will effect the sprout negatively and it may take much longer before it grows, if it grows at all. This makes it hard to sow lettuce in the middle of summer.
How? Sow the lettuce very shallow, only 1/4 inch (1/2 cm) deep, preferably with perlite as a cover material as the seeds need light to grow. If you are pre-cultivating you can sow in root trainers or briquettes. Place a couple of seeds in each plug. If all of the seeds grow, remove the plants so that you end up with one plant in each plug. If you sow directly in the vegetable garden, you should still stay with the same depth.
Water the row before sowing. This way you won’t have to water as much afterwards. This is good when you sow shallowly and there is a risk of the seeds floating away with the water. Don’t sow the seeds too close to each other — that’s just wasting seeds. If you sow with about 2 inches (5 cm) of distance in between each, you won't need to do as much culling. You can wait with the culling until the plants have grown large enough that you can use them, and this way, nothing goes to waste. In the end, the leaf lettuces should have about 8 inches (20 cm) distance between the plants, and the head lettuce about 12 inches (30 cm). Cover with a thin layer of soil after sowing and lightly moisten the soil.
Planting Them Outside
Make sure that you harden your pre-cultivated plants before you move them outside. Make them accustomed to weather and wind as lettuce has especially sensitive leaves. Plant the little plants shallowly so that the leaves themselves are not covered in dirt, if they are, they will be easily killed by root disease.
Many lettuces are quick cultures. With this I mean that they generally don’t take long from sowing to harvesting. This means that there is no need to add support fertilizer. But if you choose to plant new plants to replace the harvested ones, it is a good idea to fold in some bone meal or poultry manure to replenish the soil’s nutrient pantry. The same goes for planting lettuces that take longer to develop. They may need a snack after a couple of months. Make sure that the soil is moist, but not wet, and that the surface is loose and fine around the plants. Covering with clippings is great, but don’t place the grass next to the root of the plants, as the air needs to be able to circulate.
When? The head lettuce gains flavor from being allowed to mature properly, so wait until it has formed its proper head. If you want to use a leaf here and there before it is ready, just take from the outer leaves. The leaf lettuce can either be harvested as a whole plant or you may pick the leaves you need now and then. Don’t start picking the leaves until the plant is at least 8 inches (2 decimeters) and there’s something to get a hold of. Lettuces have a tendency to blossom during heat waves, and if that happens it's best to harvest right away.
How? You harvest head lettuce with a knife. You make a cut right below the head so that it is separated from the stem. Leaf salad can be harvested a little at the time. Pick the leaves by twisting them off of the plant so that they let go of the base of the plant.
Problems That May Arise
Lettuce and Chicory are relatively problem-free to cultivate, but snails are a common theme. The plants may be kept snail-free by protecting them with electric fencing or copper thread, or by fighting snails with traps or poison.
Another threat is downy mildew. This usually occurs during cold and wet summers when the leaves have difficulty drying. To prevent attacks, you should make sure that the salad crop has plenty of air, and that watering does not happen over the leaves and not more than necessary.