Growing Romaine Lettuce: A Gardener’s Checklist

Romaine (also called cos) lettuce is a tasty, popular type of lettuce. Romaine grows in tall heads of sturdy leaves and is very heat tolerant. It gets its name from the Romans, who likely imported it from either Greece or (more likely) Arabia.

Nutritionally, Romaine has all of the benefits of most green, leafy foods. It is full of antioxidants as well as trace minerals and fiber.

Here’s how to grow your very own Romaine lettuce at home and enjoy its many benefits.

Growing Condition for Romaine Lettuce

Does Romaine Lettuce Need Full Sun?

In comparison to other types of lettuce, Romaine is considered more heat-tolerant. Some of the most heat-resistant Romaine varieties are ‘Sparx’, ‘Jericho’, and ‘Coastal Star’.

Although heat-tolerant, Romaine grows best in cooler climates and prefers moisture-rich soil.

Many leaf lettuce varieties are prone to bolting when exposed to too much sun.

“Bolting is the term applied to vegetable crops when they prematurely run to seed, usually making them unusable. A cold spell or changes in day length initiates this behavior. It can affect a wide range of vegetables including lettuce, spinach, and fennel.”

The proclivity of lettuce to flower and go to seed is a natural survival mechanism of the plant. The only problem is that in a garden you are growing lettuce for its leaves. And when the plant is bolting, you get fewer leaves and the leaf of lettuce grows bitter.

While Romaine is slowest to bolt, unseasonal hot weather spells will cause it to bolt too.

So, here are a few ideas to help you prevent bolting:

• Grow bolt-resistant lettuce cultivars. Romaine lettuce cultivars such as ‘Sparx’, ‘Salvius’, and ‘Jericho’ are heat-resistant varieties less prone to bolting.

• Opt for the mini Romaine lettuce varieties. Planting mini-Romaines is a great way to avoid bolting. They will mature before the heat becomes too much.

• Place your plants in partial shade. Limiting sun exposure to Romaine lettuce plants will result in tastier, more leafy crops.

• Replant your leaf lettuce. Many gardeners resort to a radical approach. They dig up their plants and replant them. As a result, the plant experiences a shock and stops bolting.

How Long Does It Take to Grow Romaine Lettuce?

Romaine requires 65-70 days to mature from seed. Providing plants with plenty of water and good soil will speed growing. The faster Romaine grows, the crisper the leaves.

The mature plant can reach up to 20 inches tall.

Romaine has compact dark green leaves with taller heads compared with other types of lettuce. It will shoot up quickly if provided higher fertility.

There are many varieties that will mature within a 30-day window. Some of them can be cultivated and harvested as microgreens.

How to Plant Romaine Lettuce

Romaine grows well in nearly all types of gardens if given enough sunlight and good soil. However, it’s recommended that the seeds are started indoors as they transplant easily and will likely be healthier.

But it gets better. Romaine lends itself to different planting methods, so you can choose what suits you best.

You can plant them in:

• The garden soil outdoors

• Pots or other containers

• Traditional or raised beds

• Indoor or outdoor vertical gardens

• The hydroponic soil-free units

If you’d rather stick to the traditional method, here’s how to plant Romaine lettuce for better yields:

• Plant in early spring and late summer.

• Start springtime crops from lettuce seeds indoors to prevent bolting. You can transplant the seedlings as soon as the soil is workable. They’ll make it if the temperature dips below zero.

• Sow your fall crops directly into the garden. Bear in mind you should plant them during late summer. The fall lettuce doesn’t survive the frost, and thus, timing is everything.

• Plant your romaine lettuce every week or two to get a longer growing season. This increases the chances of a good harvest, even if perfect conditions are scarce.

• Make sure your plants have space to grow. Place them 12-18 inches apart – more space generally means larger heads. Good spacing will result in larger heads and improved air circulation.

• Transplant your seedlings when it has cooled off. Ideally in the early evening to prevent dehydration and reduce transplant shock.

Can You Regrow Romaine Lettuce?

There are a few other ways to grow lettuce at home. It’s always good to keep a few hacks under the belt.

Ever thought of putting kitchen leftovers to good use? Well, you should try it out. You can regrow Romaine lettuce this way, by reusing the plant’s stems.

And here’s how:

Before you start, make sure you hit the sweet spot when timing your little indoor harvest. If you leave your lettuce stem growing for too long, it will become spindly and bitter.

For this experiment to work, you need to shop at a local farmer’s market for fresh produce. Grocery store lettuce may never grow for you.

Here are the steps to regrow your Romaine:

1. Cut the lettuce stems roughly 1 inch from the bottom.

2. Pour 1/2 inch of water into a dish and immerse the stems into the water.

3. Position the dish near the source of natural light or under the grow light. Use regular light bulbs or LED lights.

4. Don’t forget to change the water. Do it every one or two days.

5. Your lettuce leaves and roots will start sprouting before long.

6. You should have your lettuce all grown within the fortnight. Will your lettuce grow into a full head? Not really. One lettuce head planted will give you enough ingredients for a small salad bowl serving.

7. Harvest your lettuce when it takes on a blue-green color and the center leaves get less dense.

Care Of Romaine Lettuce

Once established, Romaine plants prefer cool weather and a lot of moisture. Well-fertilized soil will mean faster-growing (and thus crisper) plants. Water regularly and often, adjusting to your climate and conditions.

The plants will need to be protected from the pests that can attack them.

What Is the Best Way to Grow Romaine Lettuce?

Growing lettuces is easy and Romaine isn’t an exception. Yet, take extra caution if your area is prone to spells of high and low temperatures or unrelenting winds.

Here’s the best way to grow lettuce in your garden:

• Use floating row cover to protect your seedlings from spring cold and summer heat alike. Alternatively, plant your lettuce next to taller plants, shrubs, or screen plants.

• To make the most of your fall crops, time maturity before lower temperatures kick in. Otherwise, the frost will destroy your yields.

• Apply fertilizer regularly. Lettuces need this to keep producing new leaves. When choosing a fertilizer, choose a label with closely matching hyphenated numbers. For example, get a 5-5-5 or a 10-10-10 blend.

• Plant more bolt-resistant varieties into the summer season.

• Water lettuce every four to five days during drought periods.

How Do You Prepare Your Soil?

Romaine lettuce propagates best in loamy soil that has good drainage characteristics. And yet, it also needs a continuous supply of moisture. So, keep the soil moist enough.

Much like other salad greens, Romaine does well in soils with neutral pH ranging between 6.0 and 6.5.

Make sure to amend the soil before spring planting so you allow the additive to activate in the soil.

Here’s how to prepare your ground bed for next season of Romaine:

• Mulch your soil to keep moisture levels in check.

• If you grow your Romaine in sandy or clay soil add compost to improve soil quality. Add 2 to 4 inches of compost to the soil, working it in 6 inches deep.

• Treat the soil with lime to keep it more alkaline.

• Fertilizing can be helpful to promote faster growth. Add a fish emulsion fertilizer to your soil. It will promote germination and prevent Romaine from tasting bitter.

• Apply nitrogen, phosphorus, and potassium fertilizer blend before planting your lettuce. An addition of 16-16-8 fertilizer will work best.

To make sure you do all you can, add an extra fertilizer four weeks after planting. Apply ¼ cup of a 21-0-0 nitrogen fertilizer on every 10-foot row of the lettuce.

Romaine Lettuce Pests and Diseases

Which Are Some of the Pests and Diseases to Look Out For?

First, you want to protect your Romaine from pests. There are many stray guests in your garden that may prey on your crispy, sweet Romaine. The typical candidates are slugs, rabbits, and other rodents. Seeing aphids munching on the lettuce leaves is also not an unusual sight.

Your Romaine garden plants can be severely damaged by shot hole disease. It’s a fungus that causes the outer leaves to develop soggy tan spots that gradually fall out. As a result, your lettuce leaves look as if they have bullet holes all around.

How Do You Deal With Pests and Diseases?

Natural remedies such as soap, diatomaceous earth, and similar tactics can alleviate most problems.

Whatever you do to amend the damage to Romaine crops in your garden, don’t resort to pesticides. The leaves will absorb them and quickly get contaminated. Instead, use natural pest repellents.

Here’s how to address the most common problems with Romaine:

• To keep rabbits out of the way, use floating row covers, chicken wire, or grow Romaine in elevated containers.

• Use slug traps or diatomaceous earth to protect your Romaine from slugs.

• Keep the soil well-drained to keep aphids at bay or physically remove them by using a hose.

• Treat shot hole disease by pruning infected stems. Rotate crops.

Harvesting Romaine Lettuce

Romaine can be picked whenever it’s big enough to use. Many gardeners peel off the outer leaves and allow the rest of the plant to continue growing in order to extend the harvest time.

Before the first frost or first really cold weather comes, harvest completely.

This can be done in one of two ways:

• Pulling the plant all the way out of the ground,

• Cutting it at ground level to create a head.

Home gardeners should strongly consider pulling the plant up. Otherwise, the roots will regrow into the messy, unorganized heads. If you’ve already harvested this way, you can use these regrown heads as cover crops. Still, this is not the happiest solution.

Want To Learn More About Growing Romaine Lettuce?

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Check out these helpful resources:

Romaine Lettuce, a PDF from University of Kentucky Cooperative Extension Service
Home Garden Lettuce, from NC Cooperative Extension