If you want to grow lettuce, you first need to decide what types of lettuce varieties to plant.
Crisphead lettuce forms into a round head, and the lettuce is all bunched up together; these are your typical Iceberg types of lettuce, such as those at your local grocery and are not heat tolerant. There are also upright elongated heads of lettuce, such as Romaine and Cos.
The loose-leaf varieties do not bunch together to form ahead, although some are termed “loose-headed,” such as butterhead.
Loose-headed lettuce such as butterhead varieties form small compact heads and are considered by many to be a gourmet treat. Some of these include Bibb, Buttercrunch, Dark Green Boston, and Tom Thumb.
Popular loose-leaf lettuce varieties include salad bowl, oakleaf, red sails, mesclun, and black seeded Simpson.
Head lettuce is harvested all at once in head form, while you can harvest leaf lettuce multiple times during the season.
Lettuce seeds are tiny and hard to plant exactly as directed. Seed tapes are an advantageous way to plant lettuce seeds. However, they cost more, and I have grown accustomed to just planting the seeds as they are.
Lettuce is a cold-weather crop. Some varieties are more heat tolerant than others, but hot weather will make the lettuce bitter and cause it to bolt (go to seed).
Your lettuce growing season is largely dependent on where you live. You can start your lettuce seeds indoors 6-8 weeks before the last expected frost date and harden them off outdoors a few days when they reach 3″-4″ tall, then plant.
I plant lettuce seeds directly in the garden in late January and early February. I sometimes also start some late-season lettuce when the weather cools off in the fall.
I use a planter that can be covered if necessary to protect against frost. It is April 8 now, and I have a good stand of Mesclun, black seeded Simpson, bibb lettuce, and salad bowl.
Some lettuce will germinate in the soil around 35 degrees, but the best germination temperature is 55-75 degrees. Lettuce plants can withstand a frost if they plants are strong and established. However, I personally won’t chance it and cover my plants if frost is predicted.
The optimum growing temperature is 45-75 degrees. Lettuce can handle a few 80 degree days if the nights are cool. Here in the deep south, that does not leave us with much of a growing period for lettuce.
Our late spring starts to bring some swelteringly hot days, and in July and August, it is not uncommon for us to see days above 100 degrees, and lettuce will not tolerate that heat.
I plant my seeds and do not worry so much about spacing between plants. I can easily thin the lettuce, and the thinnings are a delicious addition to a salad. As far as spacing between rows, your seed packet will provide those details, but typically 18″ between rows is sufficient.
Lettuce needs plenty of water and will tolerate a good bit of shade. Lettuce, again, is not very heat tolerant, so a bit of shade serves to cool things down. Many folks do not realize that lettuce is actually around 95% water, so it is not a candidate for preserving and should be eaten while fresh.
I do not use pesticides on most of the plants in my garden, particularly lettuce. I will use pesticides only in very severe cases, and it is usually on tomato plants.
My lettuce is in a bricked-up planter that is about 3′ deep. I have originally filled it with a good grade of potting soil and homemade compost. Once the lettuce is planted, I water it daily unless it rains. Once it germinates, I continue to water daily using the shower setting on my hose nozzle.
While the seedlings are young and tender, I will cover them with a large sheet of plywood to protect them in the event of hard-driving rains.
The soil in my planter is a speck of excellent quality dirt that is enriched with compost each year. I fertilize the lettuce with a nitrogen-rich fertilizer, alternating between Miracle-Gro, Monty’s Plant Food, and fish emulsion.
Soil testing is a good idea if you have the time, patience, and proper supplies. Then you can adjust your fertilizer application accordingly.
You can harvest the outer leaves when they are 3″ long and continue to do so throughout the season until the plant bolts and goes to seed. An alternative harvest method is to take scissors and cut the leaves off at about 1″ above the dirt surface, continue to fertilize, and wait for new growth. You will be able to harvest about 4 times before the plant requires replacement.
I do not usually replace the plants after the first harvest unless I planted them in January because it gets too hot here in the spring months.
If I get my lettuce out in January, I start new seedlings indoors about 2 weeks after the first planting, so I will have seedlings to replace harvested plants. I then start a few additional seedlings 1 week after that and a few more an additional week later to have staggered seedlings to plant.
Different lettuce varieties may produce better harvested one way instead of another, so you might want to experiment with the varieties you plant.
You can harvest some of the outer leaves on the loose-headed varieties, allowing the head to continue growth until harvest.
Saving Seed from Bolted Lettuce
As with most all of our vegetables, we try to let plants go to seed at the season’s end, so we have seeds for next year’s planting. However, you may encounter problems if the lettuce variety is a hybrid when it comes to retrieving seeds for next year. It is best to plant non-hybrid varieties to get seeds.
Again, it is early April here in Alabama, and I have a good stand of lettuce. Just yesterday, I carefully planted pepper plants among the lettuce, as they will grow taller and provide some shade for the lettuce as the weather warms.
After I harvest all of the lettuce, I will use that space for later season tomato plants that I start from seed. That way, we’ll have early tomatoes from the many plants we have already out and established, and later tomatoes from those we will plant in place of the lettuce.