Romaine Lettuce Growing Stages: A Beginner’s Guide

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Romaine lettuce is considered a cool-season crop. They have been known to produce very well in cooler temperatures but will stop growing when it gets too hot. 

It’s often known for being one of the most popular lettuce due to its crunchy texture and refreshing flavor. 

Romaine Lettuce

To simplify the entire process and help you grow healthy plant, the stages of growing Romaine lettuce involve:

  • Seed Preparation
  • Planting
  • Germination
  • Growth & Development
  • Hardening Off
  • Harvesting
  • Storing

Stage 1: Seed Preparation

Romaine lettuce seed

Depending on the thickness of your seed coat, you may want to nick the seed coat so that water can penetrate and activate the plant embryo. 

You can use a file or scrape them with your fingernail until you see a little white spot on the seed. This will be evidence that it has been nicked since the white spot is the plant embryo.

Stage 2: Planting

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When starting romaine lettuce, use starter plugs to minimize transplant shock and speed up growth after planting. The seeds are planted approximately 1/4″ deep in warm soil temps of at least 65°F. 

Read Also:- How To Grow Lettuce From Seed in Aquaponics

Spacing between plants depends on how big you want your heads to be but should generally be about 4″. Keep soil moist for best results. Watering daily is usually sufficient unless conditions are hot and dry.

Soil should be well-drained, rich in organic material, and kept free of competing weeds.

Stage 3: Germination

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Romaine lettuce germinates quickly, sprouting in 7 to 14 days at soil temps around 70°F. You will see 50 to 90 percent germination within two weeks if the seedlings are kept moist but not wet. 

Check daily for seedling emergence by removing plugs or thinning other types of seedlings that have emerged. If you nick the seed coat before planting, you can expect increased germination rates because water will penetrate better.

Stage 4: Growth And Development

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Seedlings grow relatively slowly during their first 1-2 months, which is expected due to shallow root system development, so don’t be discouraged if little or nothing happens. 

It’s a common misconception that romaine doesn’t germinate, but the truth is it just takes a while for the root system to develop before it can push out and start growing. Depending on how large you want them to grow eventually, they should be thinned to at least 2-4″ apart. 

If allowed to bolt, the plant will have fewer large leaves and more small leaves making it less desirable in salads. You can expect 1′ of growth per week under favorable conditions such as warm temperatures (65°-80°F) with long periods of sunlight (more than 10 hours).

Read Also:- When to Transplant Lettuce Seedlings (Do It The RIght Way)

Stage 5: Hardening Off

Before transplanting, hardening off plants allows plants to acclimate slowly from their optimal growing conditions inside the house to outside conditions, which are hotter and drier. 

This will help prevent wilting or shock from transplanting. After a week, transplant your seedlings outside somewhere where they will receive filtered sunlight for another three weeks. 

If they’re getting full sun, bring them inside at night if temperatures drop below 50°F. Romaine lettuce is not frosted tolerant, so you must choose a location that gets no lower than 50°F at night if you live in an area with typical winter low temps.

Stage 6: Harvest

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Start harvesting outer leaves when they reach about 4″ high and have developed 4-5 leaves 5-7 days after emergence during late spring/summer/early fall or plant begins to bolt, which can be encouraged by slightly more fertilizer. 

Harvesting romaine lettuce is easy because the entire plant is edible. You can harvest either by cutting or tearing leaves at their base. Individual leaves are cut close to the ground with a sharp knife being careful not to cut nearby stems or roots, which are very brittle and will break off easily. 

Read Also:- Monstera Deliciosa Plant Care Guide: Everything You Need to Know

Make your initial harvests immediately after seedlings have sprouted, but once they get large, just take outer leaves as needed without harvesting too many of them at one time since you want the plant to continue growing new leaves for harvest over an extended period.

Stage 7: Storing

Romaine lettuce has a relatively low moisture content compared to other leafy greens, so it tends to keep fresh in a refrigerator for about a week. If you want to extend the shelf life of your lettuce, then consider blanching and freezing it. 

This is because it will keep fresh for up to a year. Your best bet is cutting it into 1-2″ pieces and flashes freezing on a baking sheet before placing it in an airtight container or bag.

Romaine lettuce, Raw, 1 cup shredded

CaloriesEight calories
Total Fat0.1g


The standard advice is to space your plants at 10 to 12 inches apart with rows spaced 18 inches apart. Romaine is generally harvested as a cut-and-come-again crop, so thinning to those spacings allows you to grow several crops from one planting site!


You don’t need much – just a trowel or a dibble and scissors. The seeds are big enough to be handled by hand, but they benefit from the support of a mini-greenhouse (I’ve been known to cover my flats with plastic wrap before sowing).

Growing Romaine Lettuce Indoors

Don’t worry if you don’t have access to an outdoor space to grow romaine lettuce. You can grow it indoors during the winter on a sunny windowsill.

Read Also:- The Ultimate Guide to Bromeliad Care: Everything You Need to Know

Weed Control

One of the great things about growing romaine lettuce is that “it’s so big it hides its own we.” This means you’ll never need to weed your beds with this crop.

Soil Preparation For Romaine Lettuce

Grow romaine in soil that has been prepared to give your plants an even feeding across the entire length of their root system. That means digging down 12 inches at least and adding equal amounts of compost, aged manure, or peat moss before planting seeds or transplants.

Watering Your Romaine Lettuce

Romaine lettuce likes regular watering, so give it a good soaking every day if the weather is warm and the rootball stays dry for more than two days.

Fertilizing Your Romaine Lettuce

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Start fertilizing when you first sow your seed increases in frequency as they grow. Use an organic fertilizer at half-strength and give them another shot of nitrogen once they’re large enough to eat.

Read Also:- Spider Plant Care: Keeping Your Green Pal Thriving

Common Problems

There are very few diseases or pest problems associated with romaine lettuce. The most common issue is having small holes appear, which may have been caused by flea beetles.

These pests do not typically survive hot weather, so they’re more prevalent during early spring plantings. 

You can use Bug Blaster to eliminate them from your seedlings without using any harmful pesticides. If you have any other questions, feel free to join our Facebook Group.


Romaine lettuce is not toxic or dangerous in any way unless you have an allergy. Still, it’s probably best to limit your daily intake if you’re pregnant since every mother is different. 

It has been used as the natural treatment of constipation by eating it during pregnancy. Its high fiber content helps stimulate intestinal peristalsis, which is exactly what happens when using a laxative. 

The only significant concern associated with romaine’s growing stages is related to food safety. For example, after watercress was implicated in a 2015 outbreak of norovirus, the FDA issued new rules for growing and harvesting leafy greens, requiring specific water testing before being sold in the supermarket.

Read Also:- Growing a Bromeliad: A Guide to Bromeliad Plant Care

If you want to grow romaine lettuce, you should keep in mind the following tips:

1). If you decide to start growing romaine lettuce indoors, use 8-inch pots with drainage holes and fill them up with potting soil until about 2 inches from their top. 

The best option will be if you add a little compost or peat while filling up your pots. You should also add fertilizers while planting because they will help make a strong stem and a big head of lettuce at the end of the process.

2). If you have a garden, sow your seeds there. Be aware that this vegetable likes loose and well-drained soil, so it would be best if you plant your lettuce in a part of a vegetable patch or a border that was dug up the previous year. 

Like with growing romaine lettuce indoors, you should add fertilizers because they will increase this plant’s growth rate and productivity.

3). If you want to grow romaine lettuce during winter – start planting as early as January because the shortest day at such times is about 10 hours long, which means it will take more time for leaves to grow. 

The soil needs to be kept moist throughout the process, and all seedlings need protection from frosting or flowering by establishing cloches or polytunnels over them.

4). After the seedlings have reached about 5 inches high, thin off plants to about 10 inches apart for leaves or 12 inches apart if you grow romaine lettuce for hearts. 

You also need to cover your plants with cloches or netting against pigeons and cabbage root flies which may cause damage to certain parts of your plant.

Read Also:- Aphids vs Thrips: Differences | Common Pests Of Houseplants

5). When the plants are about 8-10 inches high, you need to hoe around the plants to cut off any weeds that may threaten your vegetable patch. You should also water between 10 and 15 times per week, especially during hot summer days.

6). The first leaves should be harvested about one month after planting, but you can still wait for another three weeks if you want heart lettuce because romaine lettuce doesn’t taste good before it becomes flimsy at its base. 

If you decide to harvest it early – use a sharp knife to cut the plant just above soil level and then remove excess soil around the roots by hand or trowel. By doing so, your plant will grow back again in a couple of weeks.

7). Harvesting is best done early in the morning when humidity levels are low and when plants are dry with no rain expected for a couple of hours or when the soil has dried up after watering. 

You should also make sure to harvest before plants start flowering because this is the beginning of the end of harvesting leaves for this plant.

8). Romaine lettuce can be stored in your refrigerator at about 34-38 degrees Fahrenheit by putting it into plastic bags. However, you need to make sure that leaves don’t touch each other. 

This vegetable can last for more than one week if properly stored, so you won’t have any problems growing romaine lettuce during winter if you follow our instructions.


Romaine lettuce undergoes fascinating growth stages, evolving from tiny seeds to crisp, vibrant leaves. Discover the secrets of cultivating this versatile green at PlantGardener. Learn about the crucial milestones in its development, ensuring optimal conditions for a bountiful harvest. Uncover essential tips for soil, water, and light to enhance each growth phase. Elevate your gardening skills with insights into pest management and harvesting techniques. Dive into the world of Romaine lettuce cultivation, and cultivate your own homegrown, fresh produce with confidence and expertise. Explore the stages, master the art, and enjoy a continuous harvest of delicious, homegrown lettuce.

Read Also:- How To Grow Lettuce From Seed in Aquaponics


Before growing romaine lettuce, you should know that this vegetable loves sunlight and that it can be grown in any part of the world where temperatures do not go below -4 degrees Fahrenheit and above 95 degrees Fahrenheit. 

It also prefers soil rich in nitrogen and potassium, even though it will grow acceptable on less efficient grounds because it’s not particularly picky when it comes to these things.

Read Also:- How to Grow Desert Lavender?


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