Where does iceberg lettuce grow
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For an early start, seeds can be started in flats 4 weeks prior to the last frost and transplanted outdoors in mid to late spring. If growing in summer, select a partially shaded location, or one that receives primarily eastward exposure to mitigate the potentially damaging effects of excessive heat upon lettuce.
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Ideally, greens should be collected early in the day, before the onset of midday sun, to prevent wilting.
Many varieties of looseleaf lettuce can be harvested numerous times during a single growing season after being cut approximately 1" above the ground.
Place it in a colander and rinse then drip dry. Do this especially if you have used chemicals on your crop. When it is dry place it in a plastic bag in the refrigerator or wrap in paper towels and place in a bowl in the refrigerator. It keeps best at 32 degrees with 96% humidity. Avoid storing lettuce with apples, pears or bananas as they release a natural ripening agent that will cause brown spots and the leaves will decay quickly.
The dust produced during cleaning causes irritation to the lungs and eyes. If cleaning large amounts use a mask and goggles or clean outdoors.How to Plant, Grow, and Care for Iceberg Lettuce
Iceberg lettuce isn’t the trendiest or sexiest vegetable by any means.
In fact, it’s been the brunt of many jokes in recent years for its bland, pale leaves slathered in fast food salad dressing. But garden-grown lettuces have historical roots far more interesting and palatable. In fact, the cultivation of lettuce goes way back to ancient Egypt and was even pictured in early Egyptian tomb paintings along with the god of fertility.
The leafy crisp green has been ubiquitous in salads and even herbal medicine for thousands of years. Iceberg types are a more recent breeding innovation from the 1920s, which have been continuously improved by small garden seed companies in recent decades. Iceberg lettuce is easy to grow, full of nutrition, and far more delicious than the tasteless, watered-down industrial types.
Given its bad reputation in modern times, there’s lots of reasons to grow your own lettuce. For one, garden grown iceberg lettuce is way more nutritious. You can also be sure that it hasn’t been treated with any toxic pesticides so common in conventional lettuce farming.
Furthermore, it is way more flavorful. There are many garden iceberg varieties that are so loaded with flavor and texture that you’ll be surprised they’re even related to that bland wedge salad at a chain restaurant.
It’s time to upgrade your salads and sandwiches with crisp lettuce grown straight from the garden. Let’s dig into how to plant, grow, and care for this infamous hydrating salad green.
Contents
- 1 Iceberg Lettuce Overview
- 2 History and Cultivation
- 3 Propagation
- 4 Planting
- 5 How to Grow Iceberg Lettuce
- 5.1 Light
- 5.2 Water
- 5.3 Soil
- 5.4 Climate and Temperature
- 5.5 Fertilizing
- 5.6 Maintenance
- 5.7 Harvest
- 6 Varieties
- 7 Pests and Diseases
- 8 Plant Uses
- 9 Frequently Asked Questions
- 10 Final Thoughts
Iceberg Lettuce Overview
| Plant Type Annual Plant Family Asteraceae Plant Genus Lactuca Plant Species Lactuca sativa Hardiness Zone USDA 1 to 11 Planting Season Spring or Fall, cool-weather | Plant Maintenance Low Plant Height 6-12” Fertility Needs Low Temperature Cool, 50-65°F ideal Companion Plants Tomatoes, peppers, onions Soil Type Well-drained | Plant Spacing: 12-18” Watering Needs Moderate Sun Exposure Full sun to partial shade Lifespan: 50-70 days Pests Caterpillars, slugs, birds, deer Diseases Downy mildew |
History and Cultivation
This is a widely adapted crop and can be grown in different climates across the US.
Iceberg lettuce is one of the most popular types of lettuce grown in the United States. While many cool-weather lettuces cannot handle warm conditions, iceberg lettuce tolerates some heat as well as some cold.
Though most of it is grown in California, it is in fact a widely adapted crop that can be grown in gardens from USDA zones 1 to 11. It also has a fascinating history dating all the way back to ancient Egypt.
What is Iceberg Lettuce?
This crisp head has many varieties that are quite diverse compared to the typical grocery store options.Iceberg lettuce is an annual vegetable variety of crisp head lettuce known for its pastel green leaves, white interior, and cabbage-like shape. Like all lettuces, it is a member of the Asteraceae or daisy family. The many layers of ruffles and ripples inside the lettuce heads make it attractive for many types of salads, and the large textured leaves taste great layered into sandwiches.
Iceberg lettuce got its name from the way the lettuce was originally packed and transported when it first became popular in the 1920s. Produce companies would cover the heads in crushed ice, making them appear like little icebergs as they made their way via trains to grocery stores around the country. The mainstream variety is actually called ‘Imperial’ or ‘New York’ and is quite bland compared to unique garden cultivars available in seed catalogues.
Today, this veggie is found in grocery stores and restaurants everywhere. You could almost call it the “all-American head lettuce” because it is such a ubiquitous backdrop for the classic flavor of cheeseburgers and wedge salads with blue cheese dressing.
Given its neutral and mild flavor, it is mostly cultivated for its juicy, crisp texture. It is one of the easiest lettuces to grow because it tolerates warmer conditions without bolting like other lettuces. It also packs a tender hydrating crunch for some of the best summer salads you’ve ever grown.
Where Does Iceberg Lettuce Originate?
Natural breeding efforts have gifted us with this crisp, hydrating head of lettuce.Lettuce (Lactuca sativa) has been cultivated in gardens and on farms for millenia. It is undoubtedly the world’s most popular salad crop and can be found in just about every cuisine on the globe. While cultivated lettuce has its origins from wild lettuce (Lactuca scariola) in the Middle East and parts of central Asia, it has come a long way since its cultivation in ancient Egypt, Chinam, Greece, and Rome.
The Latin genus name Lactuca comes from the root “milk” which refers to the milky latex-like sap found in lettuce stems and seeds. The word lettuce likely comes from the old French word “laitues” which means “milky”. But most of us never see the milky part of lettuce when it is cut from the base, instead we find the crisp green frilly leaves in our salads.
Lettuce was especially popular amongst Egyptians, who associated that milky sap with lettuce’s alleged ability to improve sexual performance and stamina.
The Romans also associated lettuce with sexual potency and consumed the less-bitter leaves in salads with vinegar and oil as a pre-digestive appetizer for meals.
In China, lettuce was often consumed as “stem lettuce” stalks similar to celery, until later when looser leafed head lettuces were developed through natural breeding efforts. By the 16th century, Europeans had improved firm-heading types that grew more as compact rosettes with less bitterness. Colonists brought the lettuce to the New World via the Bahamas in the late 1400s and was one of the first seeds sown by early gardeners in America.
Is There Any Nutritional Value?
This hydrating green makes a perfect base for any salad.Contrary to popular belief, it does have nutritional benefits. Though it is about 95% water, it is a super low-calorie vegetable that can be a source of vitamins A and C, calcium, iron, and some trace minerals like magnesium, potassium and folate.
While it isn’t as jam-packed with nutrients as famous greens like kale and spinach, iceberg lettuce is still extremely hydrating and improves gut health with fiber and prebiotics.
It is an excellent aid for weight loss and also a crisp, refreshingly neutral flavor for any salad.
Propagation
Easy propagation makes this is a beginner friendly crop.Iceberg lettuce is grown very similarly to other lettuces and is easily propagated by seed. If you don’t have a seeding setup, you can also purchase lettuce starts from a local garden store or nursery to get a head start on your lettuce-growing season. It is particularly popular amongst beginner gardeners because it germinates easily in cool spring weather and matures in less than 2 months.
Lettuce is remarkably hardy and the seeds can germinate in soils as cold as 40°F. However, it does not germinate in hot soils about 75°F. In fact, hot weather can cause lettuce seeds to go dormant, so avoid storing the seeds in a warm place. So store the seeds in a cool, dry place and prepare to sow them in trays indoors or directly in the garden in the early spring.
I recommend sowing lettuce in successions every 2-3 weeks for a continuous supply of crisp salads throughout spring and early summer.
How to Seed Iceberg Lettuce
Keep soil loose and consistently moist until germination.Prepare seed trays with a high quality, well-drained seed starting mix about 3-4 weeks before planting out. I prefer to use 6 packs or 72-cell trays. As you fill the cells, be sure not to tamp down or compress the mix too much, as lettuce seeds are very small and need plenty of aeration to germinate.
Sow 2-3 seeds per cell very shallowly on the surface (about ⅛” deep), only lightly covering with a dusting of the mix on top. They can benefit from a little bit of light to germinate. Gently water and keep trays consistently moist for 7 to 10 days until germination. The ideal germination temperature for lettuce is 55° to 65°F. Once the lettuce seedlings have 1-2 true leaves, it is important to thin them to one seed per cell to ensure each plant has enough room to mature.
How to Direct Seed
Sow in cool soils and use row cover to protect your young seedlings from pests.
You can also seed lettuce directly into your garden in the early spring. This is most commonly done for baby leaf lettuce, but you can also direct seed iceberg heads if you’d like. Sow seeds in cool soils about ⅛” deep and firm gently into the ground. For iceberg heads, sow 15-18” apart in rows 12-18” apart. For baby leaf lettuce, sprinkle 4-6 seeds per inch in bands about 2” apart.
Keep consistently moist and use row cover to keep birds and rodents out of the seedlings. You need to pay extra attention to irrigating dry or hydrophobic soils to ensure plenty of coolness and moisture for uniform germination.
Planting
Harden off for 3-5 days before planting in your garden.Lettuce is a hardy annual cool-weather crop that can be planted while night time temperatures are still frosty. This veggie often one of the very first crops in the spring garden as well as a perfect late fall salad ingredient. It’s also cold hardy and can be transplanted as early as 2-3 weeks before the last frost date, or as soon as the soil can be worked.
Iceberg lettuce should be hardened off for 3 to 5 days before planting to allow them to acclimate to more extreme outdoor weather. If young plants are properly hardened, they can handle down to 20°F in the garden.
How to Transplant Iceberg Lettuce
Do not break up the roots of your seedlings before planting.Once you have thoroughly hardened off seedlings (by moving them to a sheltered area outside of your home or nursery), you are ready to transplant into the garden. Begin by preparing a garden bed with loamy, well-drained soil and a generous helping of compost. Rake it flat and mark out a grid with rows approximately 10-12” apart and holes for the lettuce plants about 15-18” apart.
Use a hori hori planting knife or garden trowel to make a hole the size of your seedling cells. Gently wiggle the plants out of their cell trays and place in the soil without disturbing the roots. Backfill gently without compacting the soil, and water thoroughly at establishment.
Iceberg lettuce can be a magnet for hungry birds and deer, so I prefer to protect young plantings with row cover until they are established.
How to Grow Iceberg Lettuce
This low-maintenance crop makes a great addition to the garden.Iceberg lettuce is truly one of the easiest greens to grow in your garden. It’s right up there with cucumbers or zucchini. As long as you avoid planting it during the hottest months, it will gladly yield for you with very little effort.
Light
This crop prefers full sunlight to partial shade.Lettuce does best in full sunlight to partial shade with at least 6 hours of sun per day. If growing in the summer, lettuce can benefit from slightly more shade to keep it cool and prevent it from bolting. Iceberg lettuce is more resilient to warmth than other types, but still enjoys a bit of afternoon shade to prevent the leaves from getting scorched.
Lettuce is a great companion crop alongside taller, slower-growing plants like tomatoes and peppers, because they keep the soil covered while harnessing the unused space of your garden.
Just be sure that the lettuce is planted at the same time as the tomatoes so it matures before the tomato plant fully shades it out.
Water
Drip irrigation or soaker hoses are the best way to water this easy crop.Lettuce is not very drought tolerant due to its shallow root zone. It should be mulched with compost or clean straw to retain moisture, and then watered deeply at least once a week if there is not any rain. It is best to use drip irrigation or soaker hoses to prevent splashing a bunch of dirt into the lettuce heads with overhead irrigation.
In times of intense sunlight or heat, lettuce is especially thirsty and can quickly dry out. Check the soil regularly by sticking your finger in near the base of the plant. If your skin comes out clean and the top 2-3” are dry, you need to thoroughly water the lettuce bed.
Soil
Although this veggie is not too picky about soil, it’s best to have a well-drained soil mixed with quality compost.
Honestly, lettuce isn’t super fussy about the soil type. Like most garden vegetables, iceberg lettuce really enjoys a nice well-drained soil but will still grow in less-than-ideal conditions. The most important thing is cool soil temperatures.
Drainage and a bit of sandiness tend to be helpful, but I have found that lettuce will also tolerate heavy clay soils and even a bit of compaction. This is probably thanks to its shallow root zone and quick growth habit. Regardless, I always mix quality compost into my garden beds before planting to give me the best chance at success with all of my crops.
Climate and Temperature
50 to 65°F is the ideal temperatures for this cool weather crop.Iceberg lettuce is a cool weather crop that thrives best in temperatures between 50 to 65°F. It loves the cool nights of northern climates. If properly hardened off and established, the plants can handle hard frosts down to 20°F, but may have some leaf damage.
Depending on the variety, lettuces tend to bolt and go to seed in conditions over 75°F. This is why it’s important to select bolt-resistant varieties (especially for southern climates) and avoid planting in peak summer heat.
Like many garden crops, lettuce tends to be more bitter and less tender when it is under heat stress. The sweetest, crispest lettuce will undoubtedly come from spring and fall production, or winter greenhouse growing.
Fertilizing
Although not typically necessary, you can add a diluted all-purpose fertilizer if planted in poor soil.Lettuce is a notoriously light feeder that can often just feed off of any nutrients hanging out in your garden soil. Since I like to incorporate lettuce as a companion planting or rotational vegetable between other heavy feeders, I usually just let it pick up the residual fertility of other crops.
If your soil is exceptionally poor, you can fertilize lettuce with diluted all-purpose organic fertilizer or a diluted kelp emulsion at planting.
Avoid fertilizing the leaves directly with fish or kelp once the plants are larger because it can be difficult to fully rinse off.
Maintenance
Be sure to keep the soil moist with reliable irrigation.Lettuce requires little maintenance aside from regular weeding and irrigation. If a heat spell comes, sometimes I’ll toss some shade cloth over the lettuce patch to keep it from bolting.
Harvest
Cut your heads at the base, keeping all leaves intact.Iceberg lettuce is most commonly harvested by the whole head rather than “cut and come again” like oak leaf or frilly lettuce types. Once the plant has thoroughly headed up into a dense round ball, use a sharp garden knife to cut right at the base and keep the wrapper leaves intact.
Wash off the milky sap right away and dunk in water for the longest storage capacity. Iceberg lettuce likes to be dried on paper towels or in a salad spinner to prevent premature spoiling.
Varieties
With dozens of different varieties of crisp head lettuces to choose from, there will be no lack of flavor coming from your garden.
Most people don’t realize that iceberg is actually just a generic name for crisphead lettuces. Crisp head means that the lettuce forms more of a ball like a cabbage, rather than growing with outward frills like a leaf lettuce. There are dozens of different varieties of crisphead lettuces, some of which are adapted to hot southern climates and others that really prefer the cold.
Best Varieties for Flavor:
- ‘Crispino’: An organic classic iceberg type with glossy green, firm round heads that have a white interior and juicy, mild flavor. This iceberg is widely adaptable and tolerant of less-than-ideal conditions. 57 days.
- ‘Saladin’: Sweet, crisp, and refreshing classic iceberg that has tightly-wrapped dense heads perfect for wedge salads. The leaves are dark green and tinder on the edges and thicker and paler toward the center. Bolt resistant, downy mildew resistant, and great for summer growing. 62 days.
Best Varieties For Hot Weather:
- ‘Leda’: A crunchy crisphead that is tender and forms large, round, dense heads.
Light green leaves with a nice sweet flavor. Very slow bolting for hot summers. 60 days. - ‘Saragossa’: This vibrant green and red crisphead doesn’t create as much of a round “ball” as traditional icebergs, but it is crisp and sweet nonetheless. ‘Saragossa’ is one of the most heat-resistant crisphead types that is compact yet with an open habit for harvest at any stage. 45-55 days.
- ‘Red Iceberg’: Speckled burgundy and green, this iceberg is resistant to mushiness in hot weather. Heads are compact, medium sized, and bolt resistant. 63 days.
- ‘Igloo’: This strongly heat-resistant iceberg grows cool, crispy heads fairly quickly without bolting. Holds well in the garden and tastes pleasingly mild with a nice classic green color. 70 days.
Best Cold Hardy Varieties:
- ‘Gildenstern’: A vibrant green mini-iceberg lettuce that yields tightly wrapped 4” whorled heads perfect for single serving salads.
Perfect for cold early spring plantings as well as late fall. 46 days. - ‘Iceberg A’: One of the original iceberg heirlooms from 1894, this great American lettuce is firm, crunchy, and crisp. It produces cool-green medium-sized heads that are the most similar to store bought icebergs. Thrives in cool weather. 85 days.
Pests and Diseases
This resilient crop only has a few potential pest problems to keep an eye out for.Lettuce is remarkably resilient in the garden and doesn’t tend to have many issues on a home-scale. Caterpillars, slugs, deer, and birds are your biggest potential enemies. Downy mildew can also be a problem in exceptionally damp areas.
Caterpillars
These pests will chomp right through your beautiful growing leaves.Caterpillars are the most damaging of lettuce pests. They come from a wide range of butterfly or moth species that lay eggs near your lettuce plants. Each type has a different feeding pattern, but they all ultimately result in the same damage: mangled, lettuce leaves full of gnarly holes.
Hand picking is the easiest option in a small garden. Planting white alyssum, yarrow, or dill can be a great way to attract natural predators like parasitic wasps. Worst case scenario, you can use Bt (a biological organic pesticide that is made from a soil bacteria) to get rid of caterpillars on your lettuce.
Slugs
To avoid big bite marks out of your leaves, sprinkle diatomaceous earth or use Sluggo.Slugs are the slimy, fat, annoying pests that really take hold in excessively moist conditions. They can hide under mulches or just slime around in extra humid weather. Sluggo is one of the simplest organic options for killing slugs. You can also sprinkle diatomaceous earth around the base of your lettuce plants, but you will need to reapply after a rain.
Deer and Birds
Exclude deer and birds by using a thin row cover or netting.Deer and birds love crisp, tasty lettuce as much as we do. I’ve found that these are the most common predators of iceberg lettuce in the garden.
The easiest way to get rid of them is to exclude them altogether with a row cover (a thin light-transmissible fabric laid over the crop).
You can also use an outdoor cat or dog to repel deer and birds. Blood meal (a granulated organic fertilizer) is another option for sprinkling on garden margins to repel deer, however a tall fence is the most reliable long-term option in deer-prone areas.
Downy Mildew
Be sure to water your lettuce from the base to avoid this moisture-loving fungus.Downy mildew is the main pathogen that attacks lettuce. It is a fungus-like organism that causes yellowing patches and white fuzzy mold. It loves excess moisture, especially from overhead irrigation, which is why I always recommend watering iceberg lettuce from the base.
Downy mildew can get into lettuce heads and ruin them from the inside-out, so if you live in a very moist climate, consider planting downy mildew resistant varieties and increasing spacing between plants for more airflow.
Plant Uses
Use your homegrown lettuce to add a fresh, hydrating crunch to your favorite recipes.Iceberg lettuce is grown specifically for the tasty, tender round heads that are coveted for wedge salads, sandwiches, and hamburgers.
Frequently Asked Questions
Luckily, this vegetable is very easy to grow and care for. Simply plant in the spring as soon as the soil can be worked or in cool fall weather. Grow in full sun to partial shade, with soil that is well-drained, consistently moist and weed free.
Lettuce is a remarkably beginner-friendly vegetable crop that requires very little care. Seed or transplant in well-drained cool temperature soils and provide consistent moisture throughout its lifecycle. Be sure lettuce gets full sun or partial sunlight for at least 6 hours a day. Keep beds weeded and protect lettuce from birds or deer feeding on the leaves.
Iceberg lettuce is a moderately thirsty crop that needs to be deeply watered at least once a week if there is no rain.
Drought stress can lead to bitter, tough leaves. Use the “finger test” in the top couple inches of soil to check moisture. If your finger comes out clean and dry, it is time to water. It may also wilt in the heat of the day if it is thirsty.
Final Thoughts
Iceberg lettuce gets a bad rap amongst many health foodies, but they don’t realize that garden iceberg is an entirely different beast than its industrial counterparts. This crisp, mild, dense lettuce is the perfect addition to summer salads and can actually be loaded with nutrition when grown in your healthy organic garden soil.
Plus, it’s so simple and rewarding to grow. Next time you hear someone roll their eyes about iceberg lettuce, you can offer them a taste from your garden and change their mind right away!
Iceberg lettuce in the garden: cultivation and care
Iceberg lettuce is considered the best in terms of taste. Outwardly, it is similar to white cabbage, the leaves are just as juicy and crispy.
Used fresh in salads with parmesan, seafood and olive oil. It is rich in vitamins, gives satiety, while not burdening the stomach.
Iceberg lettuce tastes like Chinese cabbage. They are usually used fresh, since during heat treatment the proportion of useful substances decreases by about 60-70%. Iceberg lettuce can be used to prepare the simplest and healthiest salad: lettuce, hard grated cheese and grated boiled egg, mix everything and season with sour cream. nine0003
Growing lettuce is very easy. Planted after cabbage, celery, potatoes or cereals.
It is recommended to prepare seeds by soaking or panning before sowing Iceberg lettuce seeds. It is convenient and germination is faster.
Place and soil
Choose fertile soil with a neutral or slightly acidic reaction (pH 6-7), loam to plant the Iceberg. Avoid planting lettuce in light, dry soil.
3 ways to plant iceberg lettuce
Iceberg lettuce is easiest to grow by sowing seeds outdoors .
To do this, in early spring, immediately after the soil thaws to a depth of at least 5 cm, the seeds are embedded in the soil by 0.5-1 cm. The distance between plants is kept 25-30 cm, and between rows 40-45 cm. Cover with a film to maintain the required moisture . At a temperature of 4-5°C, the sprouts begin to germinate, withstand frosts down to -6°C. Periodically, the film is opened to ventilate the plantings, and removed when all the sprouts germinate. nine0003
Iceberg lettuce can be grown from seedlings . To do this, plant seeds in peat-humus pots and set them for 2 days in a place where the temperature regime remains 16-17 ° C, then rearrange them in a room at a temperature of 15-25 ° C until 4-5 leaves appear on the seedlings . 3-4 days before transplanting seedlings into open ground, harden them out, taking them out into fresh air. The term for growing lettuce seedlings is approximately 14 days.
Another way to grow Iceberg in the country is winter sowing .
In autumn, the site is filled with organic matter and mineral fertilizer (for 1 sq.m a bucket of compost, 3 tablespoons of nitrophoska, 3 tsp of urea and 1 kg of wood ash). Not all seeds will overwinter, so it is better to sow more. After sowing, plantings are covered with leaves.
Care
Iceberg loves watering very much. Do this every day until heads are formed, after which it is reduced. In hot weather, water late in the evening. During the rainy season, when soil moisture levels are high, Iceberg lettuce is prone to powdery mildew. nine0003
Carry out loosening, superficially, without damaging the roots.
Lettuce does not respond well to elevated temperatures and at more than 25°C flower stalks are already formed, and the leaves begin to taste bitter. The optimum growth temperature is up to 17-18°C.
Crispy iceberg lettuce grown in loose fertile soil. Nitrogen fertilizer is applied before planting and during the head formation period.
Do not oversaturate the soil with fertilizer, but support it. Remember that excess fertilizer leads to nitrate buildup. nine0003
Observe crop rotation. Every year, when growing Iceberg lettuce, it is necessary to change the landing site, returning to the previous one no earlier than after 3 years.
An iceberg head is cut when its diameter is within 10 cm. It is better to cut with a knife and in the morning, when all the leaves are full of juice. The 2 lower leaves are cut off and laid in a row, without pressing each other. Store in a cold place at a temperature of 0-2°C. Shelf life up to 7 days.
After cutting the heads, after a while it will be possible to harvest a second crop. A week after harvesting, sprouts will begin to form and of all you need to leave only one, in your opinion the strongest. nine0003
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About the Iceberg lettuce culture | Gavrish
Over a hundred years ago, the world's favorite crunchy head lettuce began to be cultivated in North America.
The name "Iceberg" is probably related to the way this salad was transported to Europe in those years: heads of cabbage were covered with ice so that they remained chilled throughout the journey.
The main advantage of Iceberg lettuce over other varieties is the possibility of its long-term storage
Due to its dense structure, it does not fade and stays fresh for a long time. It is convenient to clean and transport. However, headed lettuce forms have the longest growing season and impose special requirements on the temperature regime. Iceberg is one of the varieties of head lettuce. Its distinctive features are a crispy sweetish leaf and a dense head of cabbage.
Such lettuce reaches technical maturity on the 50-95th day after sowing. The mass of a head of cabbage, depending on the variety, can be 250-500 g, and sometimes up to 1 kg. It is possible to ensure such a high quality of products only by taking into account the biological characteristics of the culture and its requirements for climatic conditions.
More than a hundred years ago, crunchy head lettuce began to be cultivated in North America. nine0003
Growth conditions
Lettuce, like other moisture-loving plants, requires a sufficient supply of moisture in the soil and moderate air humidity. Head lettuce should be watered rarely, but plentifully.
During the beginning of active head formation, high air humidity promotes the rapid growth of plants, but then becomes one of the causes of mass disease with necrosis and other diseases (gray and white rot, downy mildew). Dry conditions cause premature flowering, especially in warm summers. nine0003
The lack of soil moisture also negatively affects the quality and size of the emerging head. At low relative humidity, lettuce quickly withers and loses turgor. Crispy lettuce withstands frosts down to -1-2 °C (after rosette formation), and at -6-10 °C the leaves are damaged, but the ability to grow is preserved. The optimum temperature for its growth and development is 15-20 °C; at temperatures above 25-30 °C, significant yield losses occur.
Due to excessively high temperatures and a decrease in air and soil humidity, the leaves become bitter in taste. nine0003
Lettuce is a light-loving plant
Headed forms are especially demanding on light: crops should not be thickened, they must be thinned out in time, otherwise small and loose heads will form.
Planting iceberg lettuce
In the largest exporting countries of lettuce, it is possible to grow it all year round in open ground, while in Russia the method of growing lettuce depends on the region and season.
By using different varieties, sowing times and cultivation methods, a continuous supply of fresh produce can be ensured.
The earliest can be obtained by growing lettuce through seedlings, sowing early varieties, then mid-season and late-ripening or early varieties (seedless method). To obtain seedlings per 1 hectare of plantings, 200-250 m 2 structures of protected ground are required at a seeding rate of 6-8 g/m 2 .
It is most effective to grow seedlings in nutrient cubes 5 × 5 cm. Seeds are sown directly into cubes or dive 6-8 days after sowing when the 1st true leaf appears. To stuff the cassettes, well-sifted wet peat is used, which is mixed with perlite. nine0003
Sow manually or with the help of seeding lines (in this case, the filling of the cassettes and watering are also mechanized). With the manual method, after filling the cassettes with peat, a bar is carried over the surface to level the substrate. Then the recesses are pressed with a stick and the seeds are laid out, watered.
Sprouted at a temperature of 16-17 °C and high humidity (up to 2 days). Then the seedlings should grow for 25-40 days, until 4-5 true leaves appear. For early plantings, hardened 5-6-week-old seedlings are used, for later plantings, younger ones. When planting seedlings, 1/3 of the cube (0.5 cm) should be above the ground. nine0003
Head crunchy lettuce planted in a 35 x 35 or 40 x 40 cm pattern. Close planting (25 x 25 cm) is practiced only in dry air conditions.
Otherwise, due to lack of ventilation, it will be affected by diseases. Head lettuce is sown directly in open ground with granulated seeds by precise sowing followed by thinning. Since lettuce is a cold-resistant crop, and its seeds are able to germinate at low positive temperatures, it is sown in the field as soon as the soil is ripe. Seeds are sown at a distance of 5 to 7 cm from each other in a row on ridges of 1 m.
Seeding rate - 300,000-400,000 seeds/ha. Thin out to a distance of 25-30 cm from each other.
Ice Lettuce Irrigation Systems
Depending on the initial conditions, most fields are pre-irrigated before planting lettuce to soften the soil and prepare the seed bed (spill a layer of soil 5-10 cm). Both sown and planted lettuce are often sprinkled (every 2-3 days) until seedlings emerge or are established (usually 6-10 days). After germination until thinning (2 to 3 weeks after sowing), watering is done less often. The fields are irrigated to soften the soil before manual thinning.
After thinning and top dressing with fertilizers, water 1 more time. nine0003
In regions with strong winds, a well-managed canal system can provide better uniformity than sprinklers. Most of the water is used up in the last 30 days before harvest. Care must be taken not to overmoisten the soil - this contributes to the development of rot. Closed pipes are often only used before harvest. The use of closed pipes ensures an even distribution of water between the furrows and keeps row spacing dry so that harvesting equipment can be deployed on dry soil. nine0003
During the ripening period, excess water and fertilizer can cause the heads to overgrow, which reduces their quality and, consequently, the cost of production. The volume of water applied is usually 750 to 1000 m 3 /ha (sprinkling) and 1000 to 1250 m 3 /ha (furrow). Lettuce on drip irrigation requires from 500 to 750 m 3 /ha. A surface drip line is installed between 2 rows of plants on 1 meter beds or 3 drip lines are installed between 6 or 5 rows of plants on 2 meter beds.
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Drip irrigation distributes water more evenly than furrow or sprinkler irrigation and it helps growers get marketable heads in fields with heterogeneous soil by maintaining high soil moisture levels throughout the field.
Iceberg lettuce nutrition
With the optimal content of available nutrients in the soil per 1 ha, add: 100 kg N, 50 kg P2O5 and 150 kg K2O3, 60 kg CaO, 20 kg MgO. Plants require nitrogen in almost all growth phases, it is recommended to apply it at planting (70 kg/ha) and at the time of head formation (30 kg/ha), and phosphorus and potassium are especially needed during the beginning of head formation. The introduction of boron, manganese and molybdenum fertilizers has a positive effect on the yield of head lettuce. Particular attention should be paid to the introduction of nitrogen fertilizers, since their excess contributes to the defeat of plants by diseases and pests, leads to excessive accumulation of nitrates. nine0003
Care, cleaning, packaging
Lettuce is thinned and weeded approximately 30 days after planting.
Mechanical cultivation is used to control weeds. Weeds must be destroyed both inside and outside the field before they produce seeds. Additional manual weeding is carried out after 2-3 weeks. As heads of normal size for the variety are formed, harvesting is carried out. This is best done in the morning or evening, avoiding hot weather. nine0003
Cut off firm heads of lettuce, 4-5 outer leaves trimmed. There are various ways to pack an iceberg. Most often, heads of cabbage are placed in a plastic bag that is not completely closed. Less common is the wrapping of heads of cabbage entirely in film.
Heads are stacked 24-30 pcs. in boxes (the weight of the box is approximately 23 kg). At the processing plant, the heads can be further trimmed, chilled, washed and cut for distribution into various types of retail packages. The entire processing plant is operated between 1.7°C and 4.5°C to keep the heads crisp and fresh. nine0003
For the successful cultivation of the iceberg, it is necessary to carry out all agricultural practices in accordance with the climatic conditions of the region, according to the season.
