Lettuce plants grow quickly, which makes them one of the most popular garden crops. They are also the gift that keeps on giving, as you can harvest them throughout their growing season.
Lettuce plants grow from seed, through seedling, to growing leaves that develop into mature heads. The growth cycle can take from 6-14 weeks. When the plants are grown from seeds, they take 2-15 days to germinate. Transplanted from seedlings, lettuce can be harvested 4-6 weeks after planting.
In this post, we explain the growing stages of lettuce and when to harvest it.
Lettuce growing stages
Lettuces grow in seven stages until maturity. They begin as seeds, then form cotyledons, which then form into a leaf bowl. This develops into the maturing leaves and the complete head. The plant then bolts, flowers and produces seeds.
The first stage of the growth of a lettuce is the seed stage.
You can plant the seeds quite freely, because they are very small.
The second stage is germination, when the seeds begin to grow underground.
The third stage is when the cotyledons appear above the surface of the ground.
These are the early seedlings.
The fourth stage is when the bowl of leaves begins to develop.
The fifth stage is the longest, as the leaves all grow and the lettuce head starts forming.
The sixth stage is bolting, when more energy goes into the stalks and they grow long.
The seventh stage is flowering, which almost coincides with bolting.
The flowers die and the seeds are dispersed.
Lettuce life cycle
The lettuce life cycle begins with the seeds, which are planted and then germinate, showing the cotyledons above the surface of the soil. The plant will then develop a leaf bowl, which grows into the mature head. The final stage of the cycle is when the lettuce flowers.
Lettuce has a life cycle from seed to seed.
The seeds are very small and are spread over the ground.
As the seeds germinate below the ground, they push up and the cotyledons will emerge into the sun and air.
The cotyledons form into leaves and a leaf bowl is formed, which is the base of the lettuce head.
The plant continues producing leaves that grow into a loose or more dense head.
When the temperatures warm up, the plant puts a lot of energy into growing stalks and leaves.
This is when the plant bolts.
Flowering also occurs just about at this stage.
When the flowers die, the seeds are released and the life cycle begins again.
Lettuce germination time
Lettuces are a fast-growing plant. Seeds that are planted in optimum conditions can germinate in as few as 2 days. Most varieties will germinate within about a week, but some varieties can take as long as 15 days.
From the time of planting, lettuce seeds can take anything from two to fifteen days to germinate.
The time frame will depend on the conditions.
This means that the soil must be the correct temperature and the seeds must receive enough water.
If the soil is relatively warm, then the seeds will germinate successfully.
Warmer soil doesn’t necessarily mean earlier germination, as too much heat may damage the seeds.
Some varieties of lettuce can germinate at lower temperatures than others.
Generally, lettuce seeds need an optimal temperature of not below 40° F (4° C) and not above 80° F (27° C) to germinate successfully.
You can read about lettuce temperature tolerance in this post.
Incorrect temperatures may delay the time of germination, or damage the seeds so that they do not germinate.
Lettuce seeds need to be watered regularly, but not flooded, to germinate.
Too much water will delay germination and may even destroy the seeds.
Too little water can also delay germination.
When to transplant lettuce seedlings
Lettuce seedlings should be transplanted when the soil is the correct temperature for them to grow and the weather is not too warm. This means in the beginning of spring until early summer. They should be transplanted in the cooler part of the day.
For the best results, lettuce seedlings should be transplanted between spring and early summer.
In the Northern Hemisphere, this means from April to July.
In the Southern Hemisphere, the time for planting is from October to January.
As with most plants, you should transplant your lettuce seedlings during the cooler part of the day, preferably the morning.
This gives you the day to establish them with the correct watering and light.
Seedlings should only be transplanted about two weeks after the last frost, so that the soil is warm enough for germination.
Don’t transplant seedlings if the weather is too warm, as lettuces prefer cooler temperatures to grow in.
How long does it take for lettuce to fully grow?
A lettuce plant will take between 6 and 14 weeks to grow into a mature plant. This depends on the variety and whether they are planted from seed, or transplanted as seedlings. Some lettuces mature early, but the season can be extended by harvesting leaves throughout the season.
Lettuces that are planted from seeds can take up to between 6 and 14 weeks to grow to maturity.
This does depend on the variety, which is why there is such a range of time.
Loose leaf lettuces can be harvested throughout the growing season, but will reach maturity when the weather becomes warmer.
Lettuce plants that have been transplanted can take between three and five weeks to grow until they can be harvested.
Read all about how much sun a lettuce needs to grow well.
When to harvest lettuce
Lettuces should be harvested when the head has reached maturity. This is before they begin to bolt. Some varieties can be harvested throughout the growth season, as they grow leaves continually, so the harvesting season is extended. The leaves should be harvested in the early morning.
Different types of lettuce can be harvested at different stages during the growth cycle.
If you want young, soft leaves, you can harvest them as early as about two to three weeks after germination.
The usual time to harvest a lettuce is when the head or the leaves reach their full size.
This is usually between 4 and 6 inches long, for loose leaf varieties.
For lettuce with denser heads, you should harvest them when the heads are a good size and solid to the touch.
Definitely harvest before the weather gets too warm.
You can also harvest most loose leaf varieties of lettuce during the growth process.
This is the idea of harvest and regrow.
You should harvest the outer leaves before they get too long and become bitter.
If you notice any signs of the plant bolting, then harvest the whole head.
The best time to harvest any part of a lettuce is in the early morning.
Make sure you read all about how to harvest lettuce.
If you want to have fun growing vegetables at home, then opt for lettuce. The plants grow quite quickly and can even be harvested during the growing season, which means more leaves for your buck.