Growing Lettuce Indoors – A Planting Guide For Beginners

A Full Planting Guide to Growing Lettuce Indoors

Hello gardeners, we are back with a new and interesting indoor topic today. The topic is all about growing lettuce indoors. Do you want to grow lettuce indoors? Well, and then you need to follow this complete article to know about growing lettuce indoors. In this article, we also discuss all the requirements for growing lettuce indoors.

Introduction to Growing Lettuce Indoors

Lettuce is also called Lactuca sativa. It is an annual plant and belongs to the daisy family, Asteraceae. It is most commonly grown as a leaf vegetable, but sometimes it is grown for its stem and seeds. Lettuce is most commonly used for salads, although it is also seen in other kinds of food, such as soups, sandwiches, and even wraps and it can also be grilled sometimes.

A Step-By-Step Planting Guide for Growing Lettuce Indoors

Guide for Growing Lettuce Indoors
Guide for Growing Lettuce Indoors (Image credit: pixabay)

Whether, you have run out of space in your garden or if you want to grow lettuce all year round, then you can grow lettuce plants very quickly and easily indoors. Because lettuce can survive in room temperature conditions with direct sunlight, it can adapt well to indoor conditions and it can even survive with basic care. Even if you have never grown a plant indoors before, all you require is standard potting soil, water, fertilizer, and even a grow light or sunny window to help your plant grow very strong. And, a month after planting lettuce, your lettuce plant will be ready to harvest.

Overview Table of Lettuce is Given Below

Botanical NameLactuca sativa
Common NameLettuce and garden lettuce
Plant TypeAnnual plant
Mature Size6 to 12 inches tall and even wide
Sun ExposureFull sun to partial shade
Soil TypeRich and well-drained
Soil pHSlightly acidic to neutral that is 6.0 to 6.5
Bloom TimeSeasonal
Flower ColourFlowers are not showy
Native AreaMediterranean 

Lettuce Varieties/Types to Grow Indoors

There are hundreds of lettuce varieties available to grow, although some vary only slightly in size or even days to harvest. For practical purposes, lettuce is divided into four distinct groups and they are listed below:

Group 1): Crisp head forms a firm head with a very crispy texture and even distinct veins. Iceberg is the most commonly grown and it is a commercial variety.

  • Ithaca

It is a very good choice for fall plants and heat can even cause the heads to be looser; resistant to bolting and it takes 70 days to maturity.

  • Summertime

Very large heads slow to bolt in the summer heat, while the heads are forming and frilly leaves resist tip burn and it takes 70 days to maturity.

Group 2): Butterhead also forms ahead, but the texture is softer and even pliable with very less distinct veins compared to the crisphead.

  • Bibb

This heirloom lettuce has remained popular over the years. It has a tender texture and takes 50 to 60 days to maturity.

  • Butter crunch

It is an American cousin of bibb, but more tolerant of hot weather and it takes 65 days to maturity.

  • Marvel of four seasons

It is a popular European variety having green leaves tipped with red and can be planted late in spring as well as late in summer and fall. It is not quite four seasons, but very close and takes 68 days to maturity.

Group 3): Loose-leaf usually forms a very good kind of bunch instead of ahead. Loose-leaf lettuce resprouts from a cut stem without losing its quality in flavour or even texture.

  • Salad bowl

It is an All-America Winner; very easy to grow and fairly heat-resistant. It also a red salad bowl variety and takes 60 days to maturity.

  • Lollo Bionda

Frilled-edge Italian lettuce is very easy to grow and it has a long harvest period. Lollo Rossa is its red cousin and takes 48 days to maturity.

  • Oak leaf

It includes many varieties and grows in a rosette and it works very well as a cut-and-come-again type 45 to 55 days to maturity.

Group 4) Cos or Romaine is an upright plant with long and have narrow leaves that look coarse but are quite tender.

  • Rouge d’hiver

Red-leafed romaine is very good cold tolerance. It also performs well in spring and summer, making it ideal for succession planting, and takes 60 days to maturity.

  • Little gem mini romaine

It is an English heirloom that grows to only 5 to 6 inches with the crispy texture and even the romaine flavour of its big brother and takes 56 days to maturity.

  • Mesclun

It is a mixture of greens; typically harvested while young, so succession planning is essential, and about a row, the foot is needed for a salad; most are cut-and-come-again varieties that means cut about 1 inch above the ground with scissors to keep it growing and takes 35 to 45 days to maturity

Choosing a Lettuce Variety That Thrives Indoors

Although most of the lettuce plants can stay very healthy indoors, you will have better success with some varieties over others. Buy any of the lettuce varieties, which are well known for growing well inside, from a garden centre or even plant nursery.

Best Container for Growing Lettuce Indoors

Lettuce Seedlings
Lettuce Seedlings (pic source: pixabay)

If an appropriate window is not available, then you can still grow lettuce indoors by using grow lights. The suitable containers for growing lettuce indoors, need to be flat and even shallow, with very good drainage, or plastic pots four to six inches in diameter with a good drainage system.

Suitable Soil for Growing Lettuce Indoors

Lettuce usually likes soil rich in organic matter, such as compost or even any composted manure. This is one plant where extra nitrogen can’t hurt since all you want from the plant is the leaf. So, you need to amend your soil before planting, and side-dress again mid-season.

Suitable Temperature and Humidity for Growing Lettuce Indoors

Lettuce grows good and best in a temperature range of about 7°C to 24°C. Hotter weather can make the leaves bitter.

Suitable Spot for Growing Lettuce Indoors

You need to place your lettuce plant near a sunny window or even a fluorescent grow light. Lettuce plants will grow best with direct sunlight. If you are in a climate with very little sun, then purchase a grow light from a plant nursery and position it about 12 inches or 30 cm overhead.

Lettuce plants usually need at least 12 hours of direct sunlight per day, with 14-16 hours the preferred amount.

Better to keep in mind that plants grown under a grow light generally need more time under the light than they would with natural sunlight. You need to aim closer to 14-16 hours instead of 12+ hours if you are using any grow light.

Planting Lettuce Indoors

You need to fill a pot with a seed starting soil mix. Then seed starting mixes are lightweight, they help your plants’ roots grow, and they are well-draining to prevent overwatering. If you cannot find any seed starting mix, then you can also create a soil made from equal parts peat moss or coir, vermiculite, and even sand.

Each lettuce plant requires at least 4 to 6 inches or 10 to 15 cm of space and a depth of about 8 inches or 20 cm. so; choose a pot that can accommodate these measurements.

Purchase pots with good drainage holes on the bottom. Then place a saucer underneath the pot to catch draining water.

You can even buy seed-starting soil mixes from most plant nurseries or even garden centres.

You need to plant your seeds approximately 1 inch or 2.5 cm apart. Then dig 4 to 6 inches or 10 to 15 cm deep hole and then place your seeds inside at about 1 inch or 2.5 cm apart. You need to limit your seeds to 4 per pot to avoid overcrowding the lettuce as it grows out. If you want to plant more than 4 seeds, then you need to prepare several pots ahead of time.

Sprinkle your seeds lightly with potting soil and even water. Take a handful of potting soil and then gently sprinkle it over the newly planted seeds. After that fill a spray bottle with water and then gently mist the seeds to avoid washing them away.

You can plant lettuce seedlings if you don’t want to wait for seeds to sprout. If you don’t want to wait for seeds to sprout, you can easily plant lettuce seedlings instead. You can use the same technique as you would for lettuce seedlings, by planting no more than 4 per pot.

You can even buy lettuce seedlings at many plant nurseries or even garden centres.

Water Requirement for Growing Lettuce Indoors

You need to just mist your seeds daily until they sprout into seedlings. When they sprout out, give your lettuce at least 1 inch or 2.5 cm of water per week. Better poke your finger in the soil once or even twice a day and then water your lettuce whenever the soil feels very dry.

The soil in the pot should be moist but not so waterlogged.

Another way to test the moisture level of the soil is just by lifting the pot. If it feels very heavy, then that means the soil is saturated with water.

Growing and Caring Tips for Growing Lettuce Indoors

Tips for Growing Lettuce
Tips for Growing Lettuce (pic source: pixabay)

You need to grow your lettuce in room temperature conditions. Lettuce grows well and best at temperatures around 18 to 21 °C. Better to turn on the air conditioner or any heater as needed to keep your lettuce plants at an even, sustainable temperature.

If the weather is very warm or cool enough outside, then you can move your plants outdoors periodically to get fresh and clean air.

You need to water your lettuce whenever the leaves wilt. Lettuce plant leaves visibly wilt when they are very thirsty. If your plant’s leaves droop off, water the lettuce until its soil is moist, but not soaking wet or even waterlogged.

The hotter or warmer the temperatures, the more often you will need to water your lettuce plant.

Fertilizer Requirement for Growing Lettuce Indoors

You need to fertilize your lettuce 3 weeks after planting it. Lettuce plant needs nitrogen-rich soil to grow, so better spray liquid fertilizer on the plant 3 weeks after you planted it, or when the first leaves grow on the plant. You need to spray the fertilizer mainly near the soil, by avoiding the lettuce leaves to prevent them from burning.

Better to use a liquid fertilizer and granular fertilizers need to be mixed into the soil.

Organic alfalfa meal or even a nitrogen-rich, slow-release fertilizer both work very well with lettuce.

You can also use fish or even seaweed emulsion fertilizers but they can emit a very strong odour and they are very less recommended for indoor lettuce plants.

Harvesting Lettuce

You can begin harvesting your lettuce 30 to 45 days after planting. On average, lettuce takes about 30 to 45 days after you plant the seeds to mature. Make a note on your calendar to start harvesting after about 30 days has passed.

Indoor lettuce plants grow and mature continually, so you’ll continue harvesting your plant after you’ve picked it for the primary time.

Mature indoor lettuce usually grows to about 4 inches or 10 cm tall.

Harvest your lettuce within the morning. Morning is when your plant is most hydrated and at its strongest. If possible, harvest your plant before the late morning or afternoon to achieve a healthier yield.

If you cannot harvest within the morning, avoid mid-to-late afternoon, which is when your plant’s least hydrated.

Cut off the outer leaves. Don’t harvest your indoor lettuce plant all directly. As long as you continue taking care of it, you’ll harvest it for several months. Cut 3 to 4 of the outer leaves at a time with garden shears or scissors, leaving the remainder of the plant to heal and grow back afterward.

Avoid picking the lettuce’s crown or centre. Limit yourself to the outer leaves to spice up its overall harvesting yield.

Refrigerate your lettuce for five to eight days after harvesting. Counting on the variability, lettuce can last anywhere between 3 to 10 days within the refrigerator. Check how long your specific variety lasts and, after placing the lettuce within the fridge, decide to use it by its expiration date.

If you do not think you’ll use your lettuce in 5 to eight days, wait a couple of days before harvesting your plant.

Harvest your lettuce again in about 2 weeks. Your plant requires about 2 weeks of healing and growing more leaves before it’s able to harvest again. After your first time harvesting, wait 2 weeks in between harvesting to stay your plant healthy and ready to grow more leaves.

Wait a minimum of 2 weeks before harvesting young plants, which can take time to grow strong after being harvested.

Sow additional seeds every 2 weeks to increase your harvest.

Commonly Asked Questions about Growing Lettuce Indoors

In case if you miss this: Terrace Gardening Tips for Beginners.

Questions about Growing Lettuce
Questions about Growing Lettuce (pic source: pixabay)

Can I grow lettuce indoors year-round?

Whether you have run out of space in your garden or even you want to grow lettuce year-round, you can grow lettuce plants very quickly and easily indoors. Even if you have never grown a plant indoors before, just all you need is standard potting soil, water, fertilizer, and even a grow light or any sunny window to help your plant grow very strong.

How long does lettuce will take to grow indoors?

It takes nearly about three to four weeks

In about three to four weeks, indoor baby lettuce should be around 4 inches tall and prepared to reap. Because lettuce is very perishable, so cut only what you would like. Starting with the outer leaves first, trim each leaf at the plant’s base, about an in. from the soil. Leave the remaining leaves to grow for a couple of days longer.

How do I grow lettuce indoors in water?

You need to cut off the bottom of the head of lettuce and place it in a very small bowl of water. Then new growth begins from the centre of the in as little as 3 days and you will have a new half-head of lettuce in nearly about 2 weeks.

Will lettuce regrow even after cutting?

Head lettuce will die down, but most leaf-lettuce plants renew efforts to supply leaves if regularly watered after trimming. Results will often be smaller than the first plant, but you’ll be ready to harvest a second, good-tasting crop within as little as a fortnight.

Why is my lettuce growing very slowly?

Lack of heading is most often caused by very high temperatures, but it can also be caused by dry soil or even oddly enough an oversupply of nitrogen. Since your leaf lettuce is very slow I would suspect a lack of nitrogen and even moisture as well as possibly a lack of light.

How can I grow lettuce all summer long?

Cut off the outer leaves when they’re 4 to six inches long, leaving smaller inner leaves. This tricks your lettuce into thinking it has not matured, by keeping it from bolting. As a final resort, obtain the whole plant and replant it during a new spot, which can cause it to specialize in growing new roots rather than getting to seed.

Why my lettuce does is keeping dying?

Problems with water: Your lettuce can start to die if it’s getting either an excessive amount of or insufficient water. The plant won’t be growing because it should, and therefore the foliage may turn yellow or wilt. If soil is just too moist, plants can get the fungal disease, and if the matter persists, the basic system is often damaged by plant disease.

How often should I fertilize lettuce?

Fertilizer for every two weeks

Because lettuces are a “cut and even come again” plant, and they need plenty of fertilizer to help them keep producing new leaves for the next harvest. So, feed lettuce plants every two weeks with a balanced water-soluble or even granular fertilizer, such as a 10-10-10 or even a 5-5-5, diluted to half strength.

Why my lettuce plant’s turning brown?

Tip burn, which causes leaf edges to twist and switch a dry brown, is caused by the plants’ shallow roots drying out. Keep lettuce plants well-watered. If damage occurs along the leaf edges, then just cut it off before consuming those leaves. Browning caused by bacterial rots may be a problem of spacing and airflow.

Is blood meal good for the lettuce plant?

Lettuce is a heavy nitrogen feeder plant. For lettuce to grow strong, it is important to feed it a nitrogen-rich fertilizer. Trifecta+ is an all-purpose fertilizer that has the good and a perfect amount of nitrogen for growing lettuce, and any other nitrogen-rich fertilizers, for example, blood meal will work very well to encourage leaf growth.


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