How Much Sun Does Lettuce Need? | Too Much Can be Bad

Homegrown lettuce is always the best. The leafy, green heads harvested from your home garden will almost always yield a fresher, crisper and better tasting lettuce compared to the heads bought at the supermarket. However, growing lettuce in your home garden can raise some questions. For example, how much sun does lettuce need?


So how much sun does lettuce need? Lettuce should receive around 6-7 hours of sunlight a day with the remainder of the time being in partial or entire shade.


When it comes to growing lettuce however, it’s not so much the amount of sunlight the plants receive rather it’s the intensity of sunlight they are receiving that’s more crucial. Therefore, the quality of the sunlight is much more important than the quantitative hours of sunlight lettuce heads get.

How Much Sunlight does Lettuce Need?

 When growing lettuce in your garden, it’s important to plant it in an area that receives some amount of shade. Lettuce does not grow all that well under direct sunlight however, prolonged overcast is just as bad too. A few lettuce varieties such as “Green Star” and “Red Sails” can tolerate excess sunlight and heat better; however most require some amount of shade.


As long as you don’t plant your lettuce in area that receives direct sunlight for most or all of the day, your lettuce will grow fine. No more than 7 hours of direct sunlight daily is a good rule of thumb for growing lettuce. Excess exposure to sunlight and heat will cause your lettuce to bolt.  

What happens when Lettuce gets too much Sunlight?

Bolted Lettuce

As discussed earlier, lettuce will bolt if it is exposed to too much sunlight. Bolting is when a plant prematurely flowers and goes to seed as a result of stress. In this case, excess heat and sunlight are putting stress on the lettuce plant. Therefore, the lettuce prematurely flowers and produces seeds in an attempt to reproduce before it dies.


Bolting is bad for your lettuce as it causes it to grow tall and skinny rather than big and leafy. Instead of leafy, robust heads of lettuce, you will get tall, spindly lettuce plants with few, low quality leaves if your lettuce bolts.

Can you eat Lettuce once it Bolts?

While there is nothing stopping you from consuming lettuce that has bolted, most people opt not to as it does not taste very good. When lettuce bolts, it utilizes the energy and sugars stored within the plant to quickly produce a flower so it can reproduce before it dies. As a result, lettuce will lose its flavor and become very bitter.

How to Protect Lettuce from Excess Sunlight

Excess sunlight is the number one cause of bolting in lettuce. Therefore, it is crucial that your lettuce is not receiving too much of it. Once lettuce begins to bolt, there’s no way to reverse it however, there are plenty of ways you can prevent bolting from occurring in the first place.

Start Lettuce Earlier in the Season:

One of the simplest ways you can prevent your lettuce from bolting is by planting it earlier in the season. Lettuce is a cool season crop so it grows much better if you plant it early in the growing season.


Although the optimum temperature range for lettuce is between 60° and 65°F (16° to 18° C), lettuce will actually germinate in temperatures as low as 40°F (4°C). Therefore it’s always a great idea to start your lettuce early on in the growing season before the really sunny, hot days arrive.

Utilize Shade Covers:

Another great way to protect your lettuce from excess sunlight is to use a shade cover. Shade covers are great for any garden because they protect the plants from the heat and sunlight of the hot summer days while still allowing air and water to pass through. This is perfect for lettuce since lettuce prefers limited sunlight.


When you use a shade cloth, you can grow lettuce as well as other cool season crops in the hottest days of summer without having to worry about bolting and excess heat and sun. Another great advantage of using shade covers is that it protects your lettuce plants from strong winds and small animals that may want to nibble on your lettuce.


Shade cloths come in different shapes and sizes depending on your needs, but they also come in different intensities as well. This means it will provide a certain amount of shade to sunlight depending on what you need. For example some shade cloths provide only 10% shade to your plants while others provide up to 90% shade. When it comes to growing lettuce, anywhere from 30% to 50% will do just fine.

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Plant Resistant Varieties:

Some verities of lettuce are naturally more tolerant of heat and sunshine than others. Therefore, choosing a more sunlight tolerable variety of lettuce may be the best option for your garden. There are four main types of lettuce; Crisphead, Romaine, Bibb and Leaf. Each of these four types has a few or more heat tolerant breeds of lettuce


Crisphead: Sierra Batavian, Nevada, Michelle.

Romaine: Coastal Star, Anuenue, Jericho, Little Gem

Bibb: Buttercrunch, Summer Bibb

Leaf: Green Star, Bronze Arrow Lose Leaf, Black Seeded Simpson.

What to do with Lettuce once it Bolts?

Once lettuce begins to bolt, there is not much you can do to stop it. If you catch it early on in the bolting phase, you can harvest the leaves before the turn bitter. However, if your lettuce is tall and lanky, it is probably too late. Although bolted lettuce may not be palatable, there are some ways you can make use of it.


One of the easiest ways to make use of bolted lettuce is to simply compost it. If you compost your lettuce as well as any other bolted vegetables, it will quickly break down and provide nitrogen to your compost pile. This will feed the microbes and lead to a healthy, nutrient rich compost you can add back into your garden next growing season.

New to Composting? Check out: Composting 101| The Ultimate Guide to Homemade Organic Compost.

Seed Collecting:

Another easy way to utilize bolted lettuce to harvest lettuce seeds from it. When lettuce bolts, it will eventually develop flowers. Each individual flower will contain a seed pod. If left on its own, the seeds will eventually drop from the plant and be dispersed via the wind to grow elsewhere. However, harvesting them before they do this is rather simple.


To harvest lettuce seeds, wait until the flowers are dry and fluffy. Then, trim the entire flower stem and shake the flower upside down over a bag so that the seeds drop into the bag. Gently crush down on the bag to separate the seeds from the seed pods. Once this is done, pour the seeds and pods onto a plate or tray. Then, lightly blow onto the seeds. The seed pods will be light enough that they will blow away while the seeds will stay on the plate. You will likely lose a few seeds in this process however; you will still have more lettuce seeds than you know what to do with!

Green Smoothie:

Although bolted lettuce is flavorless and bitter, you can use with other ingredients to make a nutritious green smoothie. With very few calories and high vitamin and mineral content, lettuce is a perfect ingredient to add to a green smoothie regardless of whether it has bolted or not.

Related Questions:

How much Water does Lettuce Need? The general consensus is that lettuce should be watered twice week. However, watering may vary depending on circumstances like climate and size of the plant. A general rule of thumb is that if the surrounding soil is moist to the touch, watering is not necessary. If the soil feels dry, water your lettuce enough that the top 5 to 6 inches of soil is moistened.


When lettuce is small and has just sprouted, watering should be done more frequently but with less water as to not damage the delicate stem and roots. After the first 2 weeks of the lettuces initial sprout, switch to the standard twice a week watering.


Why is my Lettuce Red? Lettuce turns red as a result of oxidation. As lettuce ages, chlorophyll within the lettuce gets oxidized and as a result, turns red. This process is known as “russet spotting”. While it may not look very appetizing, the lettuce is still perfectly safe to eat.


One way to mitigate russet spotting is by storing lettuce properly. In addition to refrigerating lettuce, wrap it in plastic wrap or store it in an air tight container. Also, try to keeping it out of contact from other fruits and vegetables you store in the fridge as they give off ethylene gas which also contributes to russet spotting.


Will Lettuce Regrow? Lettuce will regrow after harvesting if done properly. To harvest your lettuce so that it grows back, get a sharp pair of scissors or a knife and simply cut horizontally through the lettuce leaving at least 2 inches of the plant still remaining intact with the soil.


You will now have lettuce leaves to consume and your lettuce plant will produce fresh, new leaves in only a couple weeks.

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