They say it’s not easy being green, but romaine lettuce, with its large, leafy rosettes and emerald green leaves, sure makes it look effortless. Romaine, AKA cos lettuce, is perhaps the most popular of the many types of lettuce out there, and for great reason. Its leaves are good for so much more than caesar salads.
You can grow romaine at least six months of the year no matter where you live, either in the spring and fall or over a mild winter. And despite what those lettuce bouquets at the grocery store might have you think, you don’t have to wait for a complete head to harvest delicious leaves.
Follow along for everything you need to know to plant and grow your own romaine lettuce.
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THE BEST ROMAINE LETTUCE SEEDS TO GROW
Now that you’ve decided to grow your own romaine lettuce, you may or may not be pleased to know there are different types of romaine you can grow. For those of you who hate making decisions, I recommend just growing them all!
The Best Type of Romaine to Grow in a Container Garden
If you’re not working with a whole lot of garden space, there are varieties of romaine that have been bred to grow in pots and smaller containers. Sweetie Baby Romaine may be a more compact plant (the entire plant will only be about 6 to 8 inches tall, compared to the standard 12 to 16 inches), but its leaves are still nice and crisp.
If you want to grow standard romaine plants, you can’t go wrong with bolt-resistant Vivian Romaine Seeds from Botanical Interests. Crisp leaves, tight heads—the whole package. There’s also a heat-tolerant heirloom romaine lettuce called Jericho from Renee’s Garden that features elongated leaves. These are both great options that will give you plants that grow between 12″ and 16″ tall and about 4″ to 6″ across.
The Best Red Romaine Lettuce
Did you think you were limited to green romaine lettuce? Ruby Gem Romaine is an eye-catching little plant that grows plump rosettes only 6″ tall. The leaves start off green close to the heart of the plant and turn red near the top.
WHEN IS THE BEST TIME TO PLANT ROMAINE LETTUCE?
Romaine lettuce is a cool-weather crop that loves when temps are between 45°F and 75°F.
Here in Central Texas, our cool growing season runs from about November to March. Even though this period encompasses our winter months, this is our prime lettuce growing time. I recommend using frost cloth or floating row covers to protect romaine plants from any hard freezes we might get during this time.
For those of you who live somewhere with colder winters, the best time to grow romaine will be the spring and fall. You can plant romaine seeds outdoors as soon as two weeks before your last frost date for a spring planting.
If you’re planting in the fall, the important thing to keep in mind is that lettuce seeds germinate best in cooler soil temperatures (below 80°F). Consider starting your seeds indoors (sans warming mat) or planting them outdoors in a shaded spot of the garden. You could also use a shade cloth to keep the soil cooler.
WHERE IS THE BEST PLACE TO PLANT ROMAINE LETTUCE?
Thanks to their shallow root systems, romaine plants can grow in containers, raised beds, and even in-ground beds. Even better, romaine doesn’t need full sun, so you can pick a spot on a partially shaded patio or even indoors right next to a window.
Growing romaine in a container
You only need a container with at least 6″ of depth to accommodate the shallow roots of romaine, though I recommend sticking with a smaller variety like Sweetie Baby, Ruby Gem, or Little Gem Romaine. Make sure that whichever container you choose has good drainage holes so that the roots don’t sit in water for too long. (Check out some quick buying options for shallow containers in the LGS Amazon Shop.)
You can place weed barrier cloth or a little piece of burlap in the bottom of the container so that your soil doesn’t wash out the drainage holes. Fill your container with an organic potting soil mixed with compost to give your plants the organic matter they grow their best in.
Growing romaine in a raised bed
Romaine plants love the great drainage provided in a raised bed. Keep the mature height of the romaine variety you’re growing in mind when you’re planning out your bed so that you don’t plant heads where they’ll block sunlight from shorter plants.
Growing romaine in the ground
Loosen the first 6″ of topsoil in your bed and then add several inches of compost so that you have a rich soil for these plants. Smaller romaine varieties make beautiful (and edible!) little border plants.
HOW TO PLANT ROMAINE LETTUCE SEEDS
Romaine plants are pretty easy to grow from seed. You do have one important decision to make before you get started.
Starting Romaine Seeds Indoors vs Direct Sowing
If you have at least 60 days left of nice, cool weather, it’s faster and easier to direct sow seeds in the garden. Lettuce plants, even larger ones like romaine, don’t like to be moved thanks to their fragile little roots.
That being said, you can get a head start on your salad garden season by starting romaine seeds indoors under a grow light. (Explore my indoor seed starting guide to get started.) This is a good option if you want to grow lettuce in the fall but still have a couple more weeks of warm weather.
Steps to Grow Romaine from Seed
Follow these four easy steps for romaine planting success.
Step One: Prepare the Soil
Spread a 2″- to 3″-thick layer of fresh compost over the planting area. This will give your romaine a nice little nutritional boost.
Step Two: Make a Trench
Instead of poking a bunch of small holes in the soil, I like to draw a shallow trench in the soil with my finger. (If you want a really straight planting line, use two stakes and some twine as a guide.) Place all of your romaine seeds and then gently pinch the soil back in place over the seeds—that way, they’re only very finely covered with soil. Romaine seeds only need to be planted about 1/8″ deep.
Romaine Plant Spacing
Proper spacing will depend on the romaine variety you’re growing. Overall, smaller varieties should be planted about 6″ apart, while typical varieties should be about 10″ apart. Check the expected width of the type you’re growing, and then make sure to leave at least that much space between each plant.
Step Three: Water
Water the planting area well. While you don’t want the soil to be swampy, you never want to let it dry out completely. Seeds need consistent soil moisture to germinate and then grow. Be ready to add water to your garden daily, especially during those first two weeks. Note that containers dry out faster than raised beds and in-ground beds.
Romaine seeds should germinate within one to two weeks.
Step Four: Repeat
For a continuous supply of fresh lettuce, come back and sow more romaine seeds in two to three weeks. That way, you’ll be able to harvest more heads just as you’ve enjoyed your first batch. You can continue succession planting more romaine until you’re less than two months away from a change in the season.
PROVIDING OPTIMAL CARE FOR ROMAINE LETTUCE PLANTS
Romaine plants are pretty easy to tend as long as you’re keeping an eye on their watering needs. You don’t really need to fertilize them if they’re growing in great soil, but if you’re ever worried the plants could use more nutrients, you can water with some liquid fertilizer, or sprinkle some worm castings or compost to give them a boost.
Here are a few tips to keep romaine plants healthy through proper care.
Water Romaine Consistently
Keep the soil moist for your romaine seedlings. Once your lettuce plants are more established, check the moisture level in the soil; if you feel dry soil 1″ down, water deeply at soil level.
Instead of hand watering, I highly recommend installing some kind of irrigation system, whether it’s a drip irrigation system or an Oya planted very close to the romaine plants (with this method, you’d just keep the Oya filled with water and let the roots of the romaine plant absorb as much water from the porous vessel as they need). Drip irrigation is a great watering method that you can automate, and it gives plants the really deep watering they love while conserving your overall water usage. I recommend this DIY irrigation kit from Garden in Minutes if you’re looking for something super easy to set up.
Protect Romaine from Pests and Diseases
Salad greens like romaine are pretty desirable targets for garden pests. The best way to prevent pests from eating your leaves is to cover your garden with garden netting from the day of planting so that insects never have access. It’s too late to cover once pests are already present. If you find some holes in your leaves, just give your leaves a good rinse before eating.
Aphids can usually be handled by spraying your romaine leaves with a soaker hose. (Find more tips to deal with aphids.) Otherwise, avoid spraying the leaves of the plant to prevent disease.
Protect Romaine from the Weather
If you’re expecting a freeze, here’s how to protect your plants from cold weather for best results. And if you’re expecting high temperatures (anything over 85°F), move your plants to partial shade or use shade cloth over the garden to protect them from the summer heat. Make sure to check on the moisture level daily.
HOW TO HARVEST ROMAINE LETTUCE
A lot of gardeners think you can only harvest once romaine lettuce forms a complete head. You can actually begin to harvest about 30 days after planting by taking just the outer leaves from the plant while it works on forming a full head from the middle. In fact, you might find you prefer the flavor of younger, smaller romaine leaves if you’re eating them in a salad, while larger leaves are ideal for lettuce wraps.
This type of harvesting is important if you’ve planted your romaine a little too close together. Taking those outer leaves every couple of weeks will ensure each plant still has good air circulation.
Once the head is fully formed and firm to the touch (usually after about 50 to 65 days in the garden), you can use a clean pair of pruners to cut the plant at the base.
Note: The best time to harvest lettuce is early in the morning when the water content in the leaves will be the highest.
If the weather is warming, you might notice your romaine plants growing taller, or bolting. Romaine will produce a white sap when it’s getting ready to go to seed. You can still eat the leaves unless you find the flavor too bitter to enjoy.
Whether you’re growing romaine for tender baby greens or big butterhead rosettes, you’ll love the juicy texture and incredible flavor of this lettuce variety. Toss together a homemade caesar salad, make some lettuce wraps, or just pour dressing over an entire head and enjoy!
If you need a little help setting up your growing space, we’d love to do an in-person or virtual consultation to get you started with your lettuce and other favorite plants.
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