The star of any Caesar salad, romaine lettuce is crisp and full of nutrients. While you may be used to planting other types of lettuce, you can also grow romaine lettuce in your backyard. Read on to learn when to plant romaine lettuce and when to harvest it.
When to plant romaine lettuce: Romaine lettuce can be grown twice a year as it is a cool weather crop. Plant four weeks before the last spring frost date. You can also plant in late August or early September for a fall harvest. Keep the soil moist and the leaves covered from hot afternoon temperatures. You can either harvest individual leaves or the entire head of romaine lettuce.
Planting Romaine Lettuce in Different Climates
As a cool weather crop, romaine lettuce needs both soil and air temperatures that are above freezing but not burning. The humidity and heat of a tropical climate will not allow romaine lettuce to grow.
Romaine lettuce requires soil that is constantly moist. While you don’t want pooling water, if you let the soil dry out, your romaine will wilt. A dry climate requires too much extra water to make growing romaine lettuce worth it.
The ideal climate for growing romaine lettuce is a temperate climate. The mild spring and fall, along with the warm summers, means you can definitely get two harvests in. You can even start earlier in the spring and have a longer harvest season.
Growing romaine lettuce in a continental climate is definitely possible. However, the spring may be shorter so if you are worried about the harvest period, you may want to sow the seeds indoors, about eight weeks before the last spring frost date before transplanting them.
Likewise, you will need to be careful about a fall harvest as there can be an unexpected, early frost that kills off your lettuce.
Depending on where you live, you might be able to plant romaine in a polar climate. You will need to plant the seeds in the summer and will only get one harvest from them.
Choosing Romaine Lettuce Seeds
Green Heirloom varieties
Any time you see the word heirloom in reference to plants, it means the seeds have been saved from generation to generation and are as close to the starter plant as possible.
Green heirloom romaine varieties will give you that dark green appearance and crisp texture you want.
Red Heirloom varieties
Even though we’re most familiar with green romaine lettuce, you can find red varieties. Depending on the specific variety, the leaves can be either all red or speckled red and green.
The romaine lettuce you find in the grocery store has been crafted to create higher yields and more resistance to disease. You can find these types of seeds in gardening centers.
How to Plant Romaine Lettuce Seeds
Romaine lettuce is a cool season crop so you actually have two opportunities to grow it: in the spring and the fall. This makes it a great crop if you want to make the most of your garden throughout the whole year.
For spring planting, sow romaine lettuce seeds in early spring. You only have to wait for the soil temperature to be at least 45 degrees Fahrenheit. While this will differ depending on where you live, you can plant your seeds four weeks before the last frost date in the spring.
For fall planting, you want to give your romaine lettuce enough time to grow before frost sets in, but you also don’t want to start too early, or else the plants will wilt.
Late August or early September are ideal times for fall planting. You can create cooler soil by covering the area with water and then adding straw over top.
Before planting, take the time to really work the soil you will be planting in. Remove any rocks or large clods of dirt as this can impact the germination of the tiny seeds.
You can also take this time to work in compost to create a more nutrient-dense area for your romaine lettuce.
Romaine lettuce needs sunlight to start the germination process. It also requires partial to full sun to keep growing.
However, if you can plant in an area that has afternoon shade or at least dappled shade, it will prevent wilting.
Lettuce seeds are not only tiny but they need proper sunlight in order to germinate. Only cover the seeds by ¼ of an inch of dirt at the most. Usually, you can simply place the seeds on the soil and when you water them, they will naturally sink into the soil.
It’s best to plant rows of romaine lettuce and not worry about spacing. Once your romaine comes in, you should then thin the plants so there are 8 inches of space between them.
If you would like more of a continuous harvest, sow romaine lettuce seeds every two weeks, for a total of three plantings. This way you won’t have a surfeit of romaine lettuce all at once.
Unfortunately, romaine lettuce is a delicacy for such common pests as aphids. To deter these bugs from eating your lettuce leaves, you can plant smellier crops such as garlic or chives.
How to Water Romaine Lettuce
Moist soil is essential when growing romaine lettuce. Be sure to keep the soil nice and moist at the beginning to encourage seed germination.
If you don’t water your romaine lettuce enough, it will tell you loud and clear. If you see droopy leaves, it means you need to add more water. Don’t worry, though, as the lettuce should perk back up quickly after getting more water.
If the weather turns unexpectedly hot out, don’t be afraid to sprinkle your romaine lettuce with water or use a mister.
How to Grow Romaine Lettuce
Romaine lettuce will benefit from an application of fertilizer. Wait until three weeks after you have planted and then add a slow-release fertilizer to your garden. Nitrogen should be the key ingredient in a fertilizer you choose as this will target the leaves.
Help your romaine out by keeping the surrounding area free of weeds. However, romaine lettuce has shallow roots so be careful when pulling weeds.
You can add a layer of bark mulch around your romaine lettuce to prevent the spread of weeds and to help the soil retain moisture.
Once your romaine lettuce starts to produce flowers or a central stem and stalk, this is called bolting. Unfortunately, once this happens your lettuce will turn bitter.
To prevent bolting, keep watering, especially when it gets warm out. You can also plant taller crops next to your lettuce, such as tomatoes or corn to add a bit of extra shade.
Finally, add shade cloth to create filtered light. This will keep the area cooler, which is necessary if your afternoon sunlight is quite strong.
How to harvest romaine lettuce
There are two ways to harvest romaine lettuce and if you have a bunch in your garden, you will probably use a combination of them. Whatever you decide, however, always harvest in the morning when the lettuce has a large surplus of water in its leaves.
You can decide to harvest the entire head of romaine lettuce if you have a bunch of people coming over or if you just really like the lettuce. To know if it’s ready, check to see if it has a dark green color and if the leaves are slightly open.
Take a pair of sharp scissors and cut the entire head off. Make the cut 1 inch above the soil level.
By keeping the roots in the soil, you will actually encourage the rest of the plant to keep growing. You may even get a second harvest through this method.
If you really don’t need that much lettuce, or it’s the end of the growing season, you can also harvest your romaine lettuce by pulling the entire head out of the soil, including the roots.
Even though romaine lettuce is only sold in stores as an entire bunch, when grown at home you can choose how much you want to harvest. This is beneficial if you just want a few leaves for a single salad.
Always pick the outer leaves as these will be ready first and will encourage the inner leaves to keep growing in size. The lettuce will keep growing and you should have a few weeks of harvesting opportunity.
How long does romaine lettuce take to grow?
Romaine lettuce takes about 60 to 80 days to grow. This is relatively short and because it prefers cool weather, you can plant in both the spring and the fall.
Romaine lettuce is easy to grow, even if it isn’t the first choice for backyard gardeners. For spring planting, sow seeds four weeks before the last frost date, and for fall planting, sow seeds in late August or early September, depending on your weather.