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How to Grow: Lettuce
I must admit, I’ve been seduced by all the new, colorful, unusual greens on the market these days. But for old fashioned flavor and utility, you can’t beat lettuce (Lactuca sativa). Even lettuce has had a facelift in recent years. There are new varieties with red and green speckled leaves, lime green colored leaves, and burgundy colored leaves. I grow them in amongst the flowers they’re so beautiful. They also are a great window box, hanging basket, and container plant. I even grew lettuce in an old shoe once.
You can grow crunchy romaine heads, frilly looseleaf heads or creamy butterheads. But before you get overwhelmed with all the lettuce variety choices, it’s good to know the four basic lettuce groups and characteristics.
Crispheads form tight heads and crunchy leaves. Iceberg lettuce falls in this category and they need a long, cool growing season to be their best. Butterheads produce a smaller, looser head. They’re easier to grow than crispheads. Bibb and Buttercrunch are two common varieties of this type. Romaine or cos, forms tall cylindrical heads and have the sweetest flavor. ‘Rouge D’ Hiver’ and ‘Winter Density’ are two popular varieties. Looseleaf doesn’t form a head. They are the quickest to mature and easiest to grow. ‘Black Seeded Simpson’ and ‘Red Sails’ are two classic looseleaf varieties.
When making salads, get creative with your lettuces. Mix them with arugula, Asian greens, Swiss chard and beet greens as a mild base for these more dramatic greens. Crunchier romaines and crisphead varieties are great as a bed under summer salads, such as potato salad and cous cous. I even have a friend that will make a meal out of a stack of romaine lettuce leaves and salad dressing.
When to Plant
Lettuce is a cool weather loving crop and grows best with temperatures in the 60Fs. Although there are varieties, such as ‘Summertime’, that are more resistant to the heat, it’s best to plan on growing lettuce starting in late April or early May, a few weeks before your last frost date, and again in late summer for a fall harvest.
The best way to grow lettuce is to sow small batches or rows every 2 to 3 weeks in spring and again in late summer. In this way, you’ll avoid the notorious lettuce glut (all the lettuce is ready to eat at once) that can happen when you plant a large row only once.
To get a jump on the season you can also start seedlings indoors 3- to 4-weeks before your planting date or buy seedlings from the local garden center.
Where to Plant
Lettuce is a part shade tolerant vegetable. You only need 2 to 3 hours of direct sun a day to get a crop. This is especially true if you’re harvesting your lettuce as baby greens (picked when they’re only 2 inches tall) or growing looseleaf varieties. They need water, but don’t like wet, heavy soils. They grow best on beds raised 8 inches tall and no wider than 3 feet.
How to Plant
Amend the soil with compost and remove any rocks and debris from the bed. Sows seeds one inch apart in rows spaced 18 inches apart. You can also broadcast seeds on the top of the bed instead of planting in rows. I like to cover the small seeds with sand or potting soil so they can germinate easier. Keep the bed consistently moist.
Care and Maintenance
Once the seeds germinate and the true leaves (second set of leaves) form, thin the looseleaf varieties to 4- to 6-inches apart; romaine, crisphead, and butterhead varieties to 8- to 10-inches apart. This all assumes you’ll be growing your lettuce into mature heads. If you’re just growing them to harvest as young greens, you won’t have to thin. Protect tender seedlings from cold weather by laying a floating row cover over the plants. This is also a way to discourage rabbits and insects from eating your crop.
Lettuce is shallow rooted, so keep the plants well watered. Hand weed the rows so not to disturb the plant roots. Mulch after weeding with a layer of straw or untreated grass clippings. Since you’re growing lettuce for the leaves, make sure they have enough nitrogen fertilizer. I like to spray fish emulsion on the young plants and again a few weeks later to keep them growing strong. Fish emulsion is a very readily-available form of nitrogen fertilizer that’s gentle on plants.
Young lettuce seedlings can be subject to a fungus disease called damping off. You’ll notice seedlings rotting en mass indoors or in the garden. Avoid overwatering to prevent this disease from getting started. If it does occur, replant. Slugs and snails are one of lettuces’ biggest foes. Use beer traps to catch and kill them, copper flashing, sharp sand, or crushed sea or oyster shells to ward them off, and iron phosphate bait to lure and kill them. Slugs and snails are more of a problem during wet springs. To avoid eating a slug that hitched a ride into your kitchen, soak the lettuce in salted water. The slugs will rise to the top. Yumm.
Rabbit and woodchucks love lettuce. Fence your garden area before the seedlings emerge to prevent damage. Once a four-legged critter knows there’s something good to eat, they will try extra hard to get in the garden.
If growing any lettuce type for baby greens, start harvesting when the leaves are about 2 inches long. Looseleaf varieties are also known as “cut and come again” varieties. This means you can cut the leaves at ground level and they will resprout. You can cut a number of times before the lettuce plant gets too woody to harvest.
If growing the Butterhead or Romaine types of lettuce, about 60 days after seeding when the leaves are 4- to 6-inches long and heads formed, cut the whole plant at the ground level. These may grow more leaves after harvest, but won’t be as prolific as looseleaf types. If growing the crispheads, wait until the head is firm when squeezed before harvesting.
Beside the varieties mentioned earlier, there are some unusual lettuces to try as well. ‘Green Ice’ is a looseleaf variety with lime green colored leaves. ‘Dark Lollo Rossa’ has very frilly, burgundy red leaves. ‘Oakleaf’ comes in red and green types and features, you guessed it, oak-shaped leaves. ‘Freckles’ is a red-spotted Romaine variety. ‘Deer Tongue’ is a butterhead variety that features long, thin green or red colored leaves.
Excepted from the Northeast Vegetable and Fruit Gardening book.