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Why Is My Lettuce Bitter – 3 Main Reasons!

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As gardeners, we take pride in being able to grow our own vegetables, and we get satisfaction from seeing them grow day after day. But what if the time to harvest comes and all we have to show for our efforts is fruit or vegetables that disappoint with their taste?

Bitter lettuce is one of the most common plights of gardeners, who inevitably have to ask Why is my lettuce bitter? What did I do wrong? Was it the weather or my care? In this article, we’ll examine some of the most common reasons behind bitter lettuce, and how you can avoid that situation in the future.

Why Is My Lettuce Bitter?

Hot Temperatures

Unfortunately, one of the most common causes for bitter lettuce is the weather, and there’s nothing you can do about it. Lettuce does really well in a cool environment, and grows best while the spring is still cool, or when the summer heat has calmed down.

Now, if you planted your lettuce and temperatures rose by a lot, it’s likely that the plant understood this as a sign to start bolting and reach its final stage.

You see, lettuce will reach maturation in the summer months, during which it grows tall and bitter and starts spreading seeds to reproduce.

This is a normal process, and there is simply nothing you can do to prevent a lettuce from trying to reproduce when it judges that the time is right.

If you think this is what might have happened with your lettuce, try to understand the mechanisms, and next time check the weather for the coming weeks before planting it.


A second common cause for bitter lettuce is under-watering. Although it grows easily, lettuce actually needs more care than you might think.

The plant needs to be watered at least once per week unless it has rained in order to develop a pleasant, sweet taste. Even by neglecting it for a couple of days and letting the soil go dry, you risk making it bitter.

Why Is My Lettuce Bitter

If you think this might have been the cause, remember to water your lettuce more often next time.

Nutritional Deficiency

Finally, lettuce might become bitter as a result of a nutritional lack. To grow big, healthy and sweet, lettuce needs not only regular watering but also a soil that is rich in nutrients.

If you find that your lettuce routinely stays bitter despite watering it regularly and not planting it in high-heat season, your soil may be deficient in essential minerals.

Try to fertilize at least once per season and see what happens. It might just be that your lettuce was lacking the nutrition to reach its full potential.

What Can I Do to Prevent My Lettuce From Being Bitter?

Now that we’ve looked at some possible answers to the question “Why is my lettuce bitter”, let’s look at some possible solutions that you can implement now. After all, it’s not enough to understand the root of the problem, you probably want to be able to fix it too!

Fertilize Well

The first thing that you can do to maximize your chances of getting a sweet, mild lettuce that is bursting with flavor is to fertilize your garden ahead of time.

When lettuce season comes around, make sure that you are ready for it. You’ll even be able to find specialized lettuce fertilizer in some garden shops. You could also mix your own.

A good lettuce fertilizer should be made out of equal rations of potassium, nitrogen and phosphate, and is easy to mix yourself with ingredients you’ll find in any garden center.

Be careful not to overdo it though, nitrogen used in excess can actually cause a bitter taste in your lettuce, undoing all of your efforts!

Water More Regularly

The second thing that you can do to guarantee a sweet lettuce is to water more often. There are no strict guidelines for how often to water your lettuce since it will depend on a lot of factors.

How hot is it? How quickly does the soil dry up? Has it been raining lately? As a general rule, you’ll want to water your lettuce when over an inch of the surface of the soil feels dry to the touch.

Water generously, until the first 6 inches of soil are soaked through. Depending on the season, this might mean watering your lettuce once, twice or even three times per week.

Keep Your Lettuce Cool

If you remember the first part of this article, lettuce grows tall and bitter when it is exposed to too much heat. So one of the best things that you can do to prevent this from happening is to plant your lettuce in the shade.

If some part of your garden isn’t getting as much sun as the other part, this will be your perfect lettuce spot! If you’re struggling to find a bit of shade, think creatively.

Lettuce grows very well in the shade of other plants. So by planting it near tomatoes or other taller plants, you can give it the resources that it needs to cool down properly and avoid getting bitter.

Accept That Some Lettuce Plants Will Be Bitter

Finally, getting the perfect lettuce is a bit of a numbers game. Sometimes, you just can’t predict when the weather will get too hot, or when you’ll be away and unable to water your plants.

So your best bet is simply to plant new lettuce plants every week or every few days during the season and take good care of them. With so many lettuce plants in your garden, you’re sure to have at least one that does well!


Bitter lettuce is usually a result of one of three things: it either got too hot, or it didn’t get enough water, or it didn’t get enough nutrients.

To prevent that happening in the future, water and fertilize more often, make sure to create areas of shade around them, and plant your lettuce at different times to maximize your chances of getting a good one.

We hope that this article has been helpful to you, and as ever feel free to send us over any additional questions you may have in the comments section!