How to Grow Romaine Lettuce – Ultimate Guide

While there are many different lettuce varieties if you want a thick crisp leaf with a good crunch, nothing beats the romaine lettuce.

Romaine or cos lettuce (Lactuca sativa var. longifolia) is known for producing plants with upright heads and robust, long leaves. The densely packed leaves have a distinctive thick midrib. One of the most popular culinary lettuces, it is also pleasingly easy to grow at home. This makes it ideal for novice and nervous growers.

The crisp, green leaves of the romaine lettuce. 

Why Should I Grow Romaine Lettuce?

Growing romaine lettuce has a number of benefits. Firstly, because they have a compact upright growth habit, romaine lettuce plants require less growing space than other varieties. This enables you to maximize your available growing space.

Another advantage of the romaine lettuce is that, unlike low growing varieties which are closer to the soil, its upright growth habit (the majority of the plant forms a couple of inches above the soil surface) means that the leaves tend to stay clean.

Happily growing in beds, pots and planters, romaine leaves tend to be more resilient to slug and snail attacks. These destructive creatures tend to favor the softer foliage of other lettuce varieties.

Romaine foliage tends to be more resilient to slug and snail attacks.

Finally, this is a pleasingly cold tolerant plant that is also slow to bolt and turn bitter in the heat. Some varieties are so tolerant of colder conditions that, with the help of a cold frame or floating row cover, you can grow them well into the fall or winter.

With all these advantages in mind why not try growing your own romaine lettuce? This guide will take you through everything that you need to know.

Different Varieties to Try

There are a number of different romaine lettuce varieties that you can grow at home. Some of the most common are:

• Little Gem,
• Parris Island,
• Rainier.

Growers in cooler climates should try the Winter Density variety. This is a pleasingly hardy cold season selection which is just as flavorsome as any other romaine cultivar.

In warmer climates, Valmaine is recommended. This heat tolerant cultivar is ideal for the summer vegetable garden. Other heat tolerant varieties include

• Jericho,
• Sparx,
• Coastal Star.

As well as typical green foliage varieties, you can also find more colorful cultivars such as the red leafed Pomegranate Crunch and Cimmaron.

Forellenschluss is an attractive speckled variety while De Morges Braun produces plants with apple green centers and bronze or pink outer leaves.

Finally, Petite Rouge is a small or baby cultivar. Ideally for containers, it produces green foliage with attractive red tinges.

Like many other lettuce cultivars, romaine varieties come in a range of green and red shades.

Growing from Seed

Romaine lettuce seeds need 70 to 75 days to mature.

For an early start on the growing season, sow seeds undercover 10 to 12 weeks before the last predicted frost date. A cool weather crop, the seedlings can be transplanted into the garden 4 to 6 weeks after germination. In most, mild climates romaine seedlings happily tolerate a light, spring frost. In cooler climates either start the seedlings a little later or wait until your last predicted frost date has passed before transplanting.

Sow seeds in pots or trays filled with damp, potting soil. Sow as thinly as possible. Ideally the seeds should be spaced half an inch apart but don’t worry if you struggle to achieve this. You can always thin the seedlings out after germination.

Try to space the seeds out as evenly as possible. 

After sowing, cover your seeds with a light layer of fresh compost before placing in a propagator.

Place the propagator in a light position. A propagator with humidity or air vents, such as the Tabor Tools Propagator Tray, enables you to control the temperature and growing conditions more accurately. For germination to occur the seeds require exposure to around 15 hours of light every day. If you struggle to find a light enough position, try placing the seeds under grow lamps. While you are waiting for the seeds to germinate keep the soil moist.

Following germination, continue to water the growing seedlings regularly. You can also apply a seedling specific fertilizer once every 2 weeks for an extra boost. Harden off the seedlings before transplanting .

Transplanting Seedlings

Romaine plants do best in partial shade positions. While they also grow in full sun positions, slightly limiting the amount of light that they are exposed to helps to improve the flavor of the leaves.

Weed and work in any necessary amendments before transplanting your seedlings.

Before planting, weed and rake the soil, removing any large stones and breaking up clumps of earth. If you don’t know the pH level of your soil, this is a good time to find out. A soil test kit quickly and accurately tells you what condition your soil is in. The romaine lettuce prefers a neutral to slightly alkaline soil. Work in compost and any other amendments your soil may require.

You can also grow lettuce in pots. If you are transplanting seedlings into pots or planters, fill your chosen container with well draining potting soil. Your chosen pot should hold 2 gallons of soil for every romaine lettuce you want to plant in it. So, a 4 gallon pot will comfortably hold 2 plants.

To transplant, make a hole in the soil large enough to hold the young plant. Carefully remove the seedling from its pot or tray and place in the center of the hole. The seedling should sit at roughly the same level in the soil as when it was in its pot. You may need to add or remove soil before you are happy with the position of the seedling. Firm down the soil and water well.

Space your transplants 6 inches apart.

Starting Seeds Outside

The romaine lettuce is a pleasingly hardy specimen as are its seeds. The seeds tolerate cold weather and rarely rot in wet ground. This means that many growers don’t bother starting seeds undercover, where they can receive extra care and protection. Instead they simply start the seeds in their final position.

Before sowing your seeds, weed and rake the soil thoroughly. If you need to add any amendments to the soil this should be done a few weeks before sowing the seeds to give the soil time to settle.

Sow the seeds 6 to 8 weeks before the last predicted frost date. Before sowing any seeds I like to dampen the soil. This helps the seeds to stick in place, meaning they are less likely to be disturbed or blown away. Space the seeds half an inch apart before covering with a light layer of compost.

Following germination, the soil should be kept evenly moist. Be careful, if using a hose, not to wash the seeds away. Instead, use a watering can or a spray bottle. When the seedlings are about one inch tall, thin them out. The seedlings should be spaced 6 to 12 inches apart.

Thin the growing seedlings out so that they have plenty of room to grow and develop. 

Growing in the Fall

Growers in warmer USDA Zones, you can also sow seeds during the cooler winter months.

Start the seeds in their final position, 6 to 8 weeks before the first predicted frost date. Sow as described above. If the weather and soil are still warm when sowing, water the soil regularly to keep the seedlings cool.

Remember, while the seeds are robust and plants can tolerate light frosts, mature plants won’t survive a harsh frost.

Caring for Romaine Lettuce Plants

Once transplanted the romaine lettuce is a pleasingly low maintenance plant. Young plants will need some protection from slugs and snails. There are a number of organic solutions which are just as effective as chemical controls. If you are growing your plants in a pot or planter, use copper tape to deter slugs. Diatomaceous earth, eggshells and mulch can also be used to deter pests.

Romaine lettuce happily thrives with just a little basic care and attention. 

Water

Water after transplanting. Following that, don’t allow the soil to dry out. During dry periods, when plants are actively growing you may need to water once every 4 days. Water early in the morning and try to keep the foliage as dry as possible. A watering can may be more useful, and give you more control than a garden hose.

Fertilizing

After transplanting, apply a balanced organic liquid fertilizer once every 2 to 3 weeks. Fish emulsion can also be used. Or you can try making your own liquid fertilizer. A surprisingly easy process,  this guide takes you through everything that you need to know.

Keeping Summer Crops Cool

Some cultivars are prone to bolting during the warm summer months. Regularly water and mulch the soil around the plant to help keep roots cool and delay bolting. You can also shade heat sensitive plants with a garden shade cloth such as the YGS Perfect Sunblock Shade Cloth.

How to Harvest your Romaine Lettuce

You can cut romaine foliage either as baby greens or as full lettuce heads.

To harvest baby greens simply cut or pinch the leaves from the plant. Harvesting baby greens can start as soon as the plants are 30 days old. When harvesting, try to keep the growing point intact. This enables more foliage to form, allowing you to make multiple harvests.

Source: https://www.youtube.com/watch?v=EkvNU6dG0pA 

Alternatively, you can wait until the leafy green head reaches its full size before harvesting. Use a sharp knife to cut the entire head from the base of the plant.

If you are growing romaine lettuce in the spring and summer, make sure that you complete your harvest before the weather fully warms up. Warm weather can cause plants to bolt and turn bitter.

How to Regrow a Plant

If you harvest an entire plant you may want to try regrowing a plant from the stem of the leaf. This is best done with fresh plants.

Cut the stem around 1 inch from the bottom of the leaf. Place the cut section in a shallow dish or a small jar filled with half an inch of water. Make sure that the stem is immersed.

Place the dish in a light position or under a grow light. Remember to change the water every day. Roots and shoots usually emerge within 12 days. Allow the leaves to continue growing in their shallow container, there is no need to repot.

Source: https://www.youtube.com/watch?v=EIasiDxriWQ 

Harvest the foliage when it takes on a blue-green color and the center leaves start to open out and become less dense.

Don’t expect this method to produce a full plant. You should, however, have enough foliage to make a salad.

This is a fun way to reduce kitchen waste but, be warned, it is an unreliable method of growing fresh leaves. Sometimes the plants will fail or even bolt.

Preventing Common Problems

When planted and cared for correctly the romaine lettuce is an easy going, problem free plant. Growing in fresh soil and adopting a basic crop rotation system can also help to keep plants healthy.

As with many other plants, aphids can be troublesome. While homemade insecticidal soap is a reliable treatment. Interplanting with sweet alyssum can also help to keep plants pest free. Sweet alyssum is a great companion plant, its flowers attract hoverflies and parasitic wasps. Other good companion plant choices include marigolds, chives and garlic. All of these help to deter destructive pests such as aphids.

Rabbits also love green salad leaves. Plant covers, such as the Agfabric Floating Row Cover are a useful way to protect plants from a number of different pests. Alternatively try planting out of their reach in elevated pots or hanging baskets.

Remember to correctly space out your plants. This helps to prevent fungal issues such as damping off.

During warm, wet periods mature plants can sometimes develop bottom rot. Bacterial leaf spot may also be an issue. Both diseases can be difficult if not impossible to cure. However, both problems can be prevented by always planting in healthy soil. Other basic care steps, such as ensuring there is enough space between each plant for air to circulate and watering correctly, can also help to keep your plants healthy.

Finally, slugs and snails may also target young leaves. If you have planted in a pot of planter, copper tape is a good, organic deterrent. Diatomaceous earth can also be placed around the plants to deter destructive pests.

Crisp and green, the romaine lettuce is a great addition to the vegetable garden.

An easy to grow, versatile plant that is also rich in nutrients, antioxidants and minerals, romaine lettuce is the ideal, low maintenance addition to the vegetable garden. A perfect plant for both experienced gardeners and novices, why not pick up a packet of romaine lettuce seeds and start growing your own food today?