Lettuce is one of the most consumed veggies out there, used as the basis for salads and as a topping for countless other foods. Consequently, a lot of people want to know how to grow their own.
And one of the most common, and important, questions about growing lettuce is: how much sun does it need to grow?
Most types of lettuce only need between 6 and 7 hours of direct sunlight to thrive. It should be noted that lettuce does need shade the rest of the time in order to prevent it from wilting or bolting.
Lettuce is easy to grow when conditions are right, but providing those conditions on a full-time basis can be plenty tricky.
Too much sun is bad, but so is being shaded all the time. Keep reading to learn what you need to know about the sunlight requirements of lettuce.
Does Lettuce Need Full Sun?
No, not exactly. Most kinds of lettuce have some full-value sunlight every day, but they need shade the rest of the time, either full or partial.
So lettuce needs plenty of sunlight to grow properly, but it won’t grow well or at all in a sun-soaked area.
How Many Hours of Sun Does Lettuce Need?
Most kinds of lettuce need between six and seven hours of sunlight every day. This is direct sunlight, mind you.
Some lettuces will do just fine with as little as four hours of sunlight, but six to seven is about average. Any more than that and your lettuce may start to bolt due to stress.
More on that in a minute. It’s important to keep an eye on how much sunlight your plants are getting.
If you live in an area with very long days during the summer or is known for the intense, full-value sun in the cooler seasons, you may need to provide some shade for your lettuce during the peak hours of sunlight.
Can Lettuce Grow in Shade?
Lettuce won’t grow when fully shaded all the time, but it needs shade every day, the same as it needs sunlight.
This is why lettuce is often grown in generally shady areas that will only reliably get some full-value light during an average day.
Can Lettuce Get Too Much Sun?
Lettuce that gets too much sun will quickly wilt and become stressed. When this happens, it may bolt.
Bolting is when lettuce produces flowers and sets seed instead of continuing to grow leaves.
Most plants have a life cycle that includes a growth stage, a reproduction stage, and a resting stage. After the resting stage, the plant will break dormancy and begin growing again.
However, if conditions are unfavorable, the plant may go into bolting.
Bolting is when a plant prematurely produces flowers or seeds in an attempt to reproduce before it has enough energy reserves to do so.
This process is usually triggered by stressors such as extended periods of drought or heatwaves.
While bolting may help the plant to reproduce, it comes at the expense of the parent plant’s health.
Bolting also uses up a lot of energy, leaving the plant weakened and susceptible to disease. In some cases, the plant may even die before it can produce seeds in the first place.
For gardeners, bolting can be frustrating because it can cause plants to produce tasteless or bitter vegetables.
However, understanding the bolting process can help you to be better prepared for dealing with it. It is important to note that there is no way to halt bolting once it has been triggered.
Do Different Varieties of Lettuce Need More or Less Sun?
Yes. Various lettuce cultivars may have wildly different sunlight requirements.
Lettuce comes in many different varieties with the most common type of lettuce being iceberg, which has a crisp texture and mild flavor.
Romaine lettuce is another popular type that has a slightly bitter taste and a crunchy texture. Other types of lettuce include butterhead, looseleaf, and Bibb.
Each type of lettuce has its own unique flavor, but most important to us its own light requirements.
Some lettuces, like iceberg, need more sun than others. In fact, romaine lettuce needs about eight hours of sunlight every day to grow properly.
Other types of lettuce, like bibb and butterhead lettuce, can get by with as little as five hours of sunlight a day.
What Happens if Lettuce Don’t Get Enough Sun?
Most lettuce that isn’t getting enough sun will turn “leggy”. Leggy means that the stem of the plant becomes very thin and spindly as it stretches out to try and reach the sunlight.
The leaves of a leggy lettuce plant will also be smaller than normal.
If you live in an area with short days during the cool season, you may need to supplement your lettuce plants with artificial light. This can be done with fluorescent grow lights.
The important thing is to make sure that the lettuce plants are getting the right amount of light every day.
Likewise, too little sun may induce your lettuce to bolt due to stress, the same as getting too much sun or being exposed to high heat. It’s vitally important to constantly assess how much sunlight your lettuce is getting.
Can Lettuce Grow with Indirect Sun?
Yes. Lettuce can be grown successfully with sufficient indirect sunlight or indoors. Indirect sunlight is sun that has been reflected or diffused.
It’s important to remember that lettuce needs a minimum of six hours of direct sunlight every day to grow properly, but it will need more hours of indirect sunlight since the light “value” is lower than it would be if it were direct.
For comparison, lettuce relying on indirect light only will need about 1 1/2 to 2 times as much light.
So, if your lettuce requires about 6 hours of direct sunlight daily, it will need 9-12 hours of indirect light.
Lettuce can also be grown indoors under artificial lights. If you are growing it indoors, you will need to provide a minimum of eight hours of light every day depending on the strength of your lamps.
As always, pay close attention to all the other variables needed for growth, and double-check the wattage and type of your bulbs: grow lamps can easily scald lettuce if they are too intense!
Transitioning Lettuce from Indoors to Sunlight
If you are planning on moving indoor lettuce to fulltime outdoor conditions, you’ll need to do things right or else your plants can easily stress out and bolt or die.
Introduce your lettuce plants to the outdoors gradually, starting with an hour or two of sunlight and increasing the time they spend outside by an hour each day.
Continue this for a week at the minimum, though two is more likely necessary. Once they have acclimated to outdoor conditions, you can plant them in their final location.
Tom has built and remodeled homes, generated his own electricity, grown his own food and more, all in quest of remaining as independent of society as possible. Now he shares his experiences and hard-earned lessons with readers around the country.