The Ultimate Guides To Growing, Caring and Harvesting Lettuce

Avid salad eaters should always plan to grow lettuce in a home garden. Lettuce is easy to grow, looks very attractive in a garden, and matures rapidly. Gardeners should not overlook lettuce when planning for the growing season, if for no other reason than to save money on buying salads at the grocery!

Plant Chronicle

  • Common Name: Lettuce, Garden Lettuce
  • Scientific Name: Lactuca sativa
  • Family: Asteraceae
  • Light requirements: Tolerate partial shade
  • Temperature: 45-70 degrees Fahrenheit
  • Humidity: Moderate humidity, 50-70%
  • Soil Preference: Rich and Moist Soil
  • Fertilizer: Well-balanced fertilizer, right after the seedlings emerge.
  • Pests: Slugs, Aster Leafhoppers, Aphids, and Cutworms
  • Diseases: lettuce drop, bottom rot, and downy mildew

lettuce vegetables

Cool Weather Crop

Lettuce is a cool weather crop. Ideal temperatures are between 45 and 70 degrees and therefore, should be planted in either early spring or late summer. Intense summer heat tends to make lettuce have a bitter taste, so gardeners should avoid growing it during hot summer months. Seeds can be started indoors a few weeks before the last frost is expected, then transplanted to the garden. Small plants should not be set out if there is still danger of a frost; although lettuce can withstand cool temperatures, it will not endure frost.

There are basically 5 types of lettuce

  • Leaf – the easiest and fastest to grow with leaves growing loosely on a stalk
  • Romaine (sometimes called Cos) – Forms an elongated, upright head. Romaine lettuce has a slightly bitter flavor and has a crispy texture. Cos is the most common lettuce used in a Caesar salad. Like other common lettuce types, romaine lettuce is a popular main ingredient for all types of salads. Romaine lettuce forms tight and tall-upright heads.
  • Crisphead – Crisphead lettuce is more commonly known as iceberg lettuce.  It requires most care and only grows in the north because of high sensitivity to heat (iceberg is the most popular). Iceberg lettuce has a very light flavor and is known for its crispy texture. Because of its crispy texture, iceberg is the most common type of lettuce used for sandwiches and hamburgers. Iceberg is also commonly used in salads. Because of its light flavor, other ingredients added to an iceberg salad takes over the flavor of the salad. Crisphead lettuce forms a very dense and thick head.
  • Butterhead – small and forms loose heads with tender soft leaves. Butterhead lettuce got its name because the leaves have a buttery smooth texture. It has a very subtle flavoring and is more commonly used in fresh salads. Boston, bibb, and buttercrunch are some of the more common types of butterhead lettuce. Butterhead varieties form a loose-leaf head with thicker leaves than other common lettuce varieties.
  • Stem (or asparagus lettuce) – commonly used in Chinese dishes and have enlarged seed stalks.

How to Grow Lettuce from Seed

lettuce seedling

Lettuce seed tends to have a short shelf-life, so it is a good practice to sow the seeds in the year they were packaged. For this reason, be wary of seeds obtained through a seed swap or exchange.

Interesting varieties of lettuce green seeds are becoming easier to find commercially, from many seed companies. Members of organizations such as Seeds of Diversity or Seed Savers Exchange quite often offer up unique heirloom varieties of lettuce seeds, also.

Generally speaking, lettuce seeds should be directly-sown half an inch deep in rich, moist soil. Seeds can be sown thickly, the young plants thinned later on. Keep the plants weeded and watered. Plant seeds in succession a few weeks apart, ensuring a continuous crop, until the weather gets very hot.

In hot weather, lettuce plants will “bolt”, or flower, at which time the leaves will become too bitter to eat. A new crop can then be started when the weather cools down in early autumn.

With most varieties, seeds should be planted ¼ to ½ inch deep in single, double or triple rows about 14 inches apart. A good rule of thumb is to place 10 seeds per foot.

The leaf should be thinned 4 inches apart, Romain and butterhead 6 to 8 inches apart. Seedlings that have been thinned can be transplanted or eaten. If trying crisphead varieties, they should be thinned 10 to 12 inches apart.

Seeds should be purchased every year as viability isn’t good after the year is over. Store seeds to be used in the fall in the refrigerator and then throw away those that aren’t planted. Lettuce prefers loose soil with a slight acidic edge of about pH 6.0 to 6.5.

Lettuce has very shallow roots. Because of this, it should be cultivated very carefully or you could pull up plants. Frequent light watering will cause leaves to develop rapidly; however, overwatering can lead to disease and burning of the leaves.

Beds should be kept moist but not soggy. Mulch can help keep the soil temperature cool and help lettuce grow better. Growing lettuce in the shade of taller plants like corn or tomatoes can help growth in warmer weather.

Growing Lettuce in a Container Garden

Nothing tastes better than fresh vegetables from the garden. One of the easiest to grow is lettuce and other greens. Because of their shallow root system and hardiness to light frost, lettuce is ideal for container gardens. Plant two or more containers in a sunny spot near the kitchen for fresh salad throughout the season.

lettuce container

Choosing Containers and Lettuce Varieties for Vegetable Gardens

Lettuce is a great crop for small spaces. It doesn’t require a large or deep container making it ideal for patio gardens. Planting lettuce in containers allows gardeners to plant even earlier than in the garden. Lettuces thrive in temperatures less than 70 degrees and can even withstand a light frost. The container can be brought in temporarily to avoid a deep frost.

Bowl planters are the perfect containers for growing lettuces. These are containers which are 10 to 15 inches wide but only 5 to 6 inches deep. Other suitable containers include window boxes, shallow tubs or reclaimed rain gutters. Choosing containers that are easy to move allows for bringing them in if necessary or moving them out of the way of garden pests, such as rabbits.

Varieties to consider planting include leaf lettuce, radicchio, curly endive, and arugula. Mesclun is a seed mix of baby lettuces which makes a delicious and interesting salad. Planting two or more varieties two weeks apart will provide fresh greens throughout the season.

Planting Lettuce in Container Gardens

Lettuce can be planted in containers when the daily temperature averages around 45 degrees and nighttime temperatures are above freezing. Choose good quality potting mix and add time release fertilizer or compost as lettuce requires a fair amount of nutrients for good growth. Make sure the container has adequate drainage.

Evenly sprinkle seeds on the soil surface. Lightly press them into the soil for a planting depth of an approximately ¼ inch. Gently water the container so as not to disturb the seed placement. The mist setting on a watering wand or a spray bottle works well for the initial watering. If using a watering can, it may be best to water the soil before planting seeds.

Harvest lettuce when the leaves are large enough to use or approximately 4 to 6 inches high. Letting them grow too large or allowing them to bolt results in bitter and unusable lettuce. Leave an inch of the plant to continue growing for more fresh greens. A bowl container can provide fresh salad for a family of 4 up to 2 months.

Lettuce is one of the easiest vegetables to grow in containers. Because it does well in small containers it’s ideal for patio or balcony gardens. Start lettuce seeds early in containers for a jump on fresh vegetables in spring.

Growing Lettuce Indoors with Hydroponics

With modern growing methods and transportation, one can purchase lettuce and spinach year ‘round, but often at high prices. However, a gardener may find that picking up a package at the grocery store is nowhere near as satisfying as picking lettuce at home a few minutes before eating it. Applying hydroponic growing methods for lettuce crops allows the home gardener to have fresh lettuce grown in a greenhouse or basement.

Hydroponic Lettuce

Setting up a Hydroponic System to Grow Lettuce

Hydroponic systems give the gardener control over the conditions that affect plant growth allowing optimization of nutrients, light, and temperature. Because lettuce grows quickly using hydroponic methods, maturing within 30 days, it does not suffer from the oxygen deficit that can occur with crops that having longer growing cycles according to Betterbuy Hydroponics research.

A hydroponic growing system uses plant trays to hold the growing medium, Oasis root cubes, or plant containers with growing medium supporting the seedlings. The plant tray, cubes, or containers are set above a flood tray allowing the nutrient solution to flow through the lettuce plant roots. The nutrient solution is pushed into the plant tray with a pump that is placed in the nutrient reservoir container and excess solution is returned to the reservoir through a drain tube connecting the plant tray and the reservoir.

Grow lights are suspended above the plants. Humidity is reduced using vents or fans and temperature is controlled through auxiliary heating or cooling. Each of these conditions—light, nutrition, and temperature—is monitored by sensors and controlled with timers.

Best Hydroponic Conditions to Grow Lettuce

For home gardeners carefully placing individual lettuce seeds into pots or distributing them evenly across the growing medium is challenging, but doable. For commercial gardeners sowing thousands of lettuce seeds, using an automatic seeding system or encapsulated seeds is a more viable approach.

The Cornel University Lettuce Handbook suggests using a constant fluorescent light for germinating lettuce seeds. They specifically discourage the use of incandescent light because of the heat generated and because the red wavelength in incandescent light causes the lettuce plants to stretch and become leggy. Plants should have light between 14 and 16 hours per day. After germination, a grower may continue to use fluorescent lights or switch to high-pressure sodium grow lights.

Use a commercial nutrient solution for growing lettuce. Germination temperatures should be around 40 degrees. After germination, the ambient temperature can be gradually raised to between 65 and 70 degrees during daylight and cooler in darkness.

Aspiring hydroponic vegetable growers can build a system from scratch using readily available materials or they may purchase complete systems. Although there is an initial capital expenditure, most of the hydroponic system components can be re-used for many growing cycles.

Lettuce Care

The most important thing to remember about growing lettuce is to water regularly. Lettuce needs regular moisture and gardeners should water as often as needed.

Disease control can be very time-consuming, as lettuce is prone to many different kinds of problems, such as lettuce drop, bottom rot, and downy mildew. Crop rotation and using raised beds can help combat these problems.

Insects are always a problem in the garden, and lettuce is not immune. Insects that commonly attack lettuce include slugs, the aster leafhopper, and cutworms. Organic pesticides are recommended to protect plants, such as Neem or insecticidal soap.

Aphids and rabbits are especially harmful to spinach.

Aphids spread viruses that damage and destroy spinach. If you discover aphids on your spinach plants, hose the insects off immediately or use nature insect repellents.

Rabbits, like people, also find spinach to be especially tasty. Use fencing or chicken wire to prevent rabbits from invading your garden. You can also attach aluminum pie pans to sticks. The noise will scare rabbits and other animals away.

Over-watering can also pose a risk to spinach because excessive moisture can allow fungal growths, including downy mildew (blue mold) and fusarium wilt.

Harvesting Lettuce

Harvesting Lettuce

Different varieties of lettuce are ready to harvest at different times.

Looseleaf varieties mature very quickly, and gardeners can simply cut the tops of the leaves when they are a few inches long, leaving the roots to grow more. Head lettuces are ready for harvest when firm and fully-formed. These should be cut off level at the ground.

Lettuce should always be washed thoroughly before eating, particularly if insecticides have been used. It is important to read the directions on chemical controls carefully, as there will be a schedule for how long to wait after spraying before harvest.

Freshly-harvested lettuce can be stored in the refrigerator and will keep for a few days to a few weeks, depending on the variety.

Using Lettuce in Decorative Gardens

Lettuce need not be limited to vegetable gardens! For a striking contrast, try planting lettuce in the front of perennial borders stocked with dark-colored flowers. Not only will the lettuce fill in the border, but it will also set a nice contrast for bright red and deep purple flowers. Looseleaf varieties such as Heatwave make attractive front-of-the-border plants.

Lettuce growers will be rewarded with a continual harvest if insect and disease control tips are heeded, different lettuce varieties are used, and plants are tended to regularly. What a reward it is to grow a salad right in the backyard!

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About the Author

With the endless passion for organic living, I - Ann Sanders has come up with the idea of creating A Green Hand. Being the founder and editor of A Green Hand, my goal is to provide everyone with a wide range of tips about healthy lifestyle with multiform categories including gardening, health & beauty, food recipe,...

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