5 Reasons Your Aerogarden Lettuce Is Bitter


Anyone who has grown Aerogarden lettuce and found that it is bitter might be very disappointed, and if that has happened to you, you may be wondering what has happened and how you can avoid it happening in the future.

Fortunately, there are solutions to this issue!

To fix the problem of bitter lettuce, you need to identify the cause. There are several potential reasons, including improper storage, the recent addition of nutrients, or too much heat. Old lettuce also tends to be bitter, so it may be time to remove the crop and start again.

Reason 1 – Improper Storage

Lettuce needs to be stored well once it has been harvested, and the companions it shares the fridge with matter a surprising amount.

The lettuce must be kept in the fridge, but it should not be placed in the same drawer as fruits such as pears, bananas, or apples.

Infographics 5 Reasons Your Aerogarden Lettuce Is Bitter
Bitter aerogarden lettuce

These fruits release ethylene gas, which prompts ripening, and they will quickly spoil your lettuce and make it taste bad. However, freshly harvested lettuce can also be quite bitter.

If this is the case for you, place it in the fridge in a very humid drawer for two days, at around 32 degrees F. This should reduce the bitterness over the two days.

Key Takeaway: Storing your lettuce properly will help to retain its sweetness and make it last for longer.

Reason 2 – The Recent Addition of Nutrients

When using an Aerogarden, you will be adding nutrients to your lettuce on a fairly regular basis – but you should try to avoid doing so at harvest time.

When you have just added nutrients, you will make your lettuce bitter because it will have just started absorbing them.

This effect lasts for a day or two, so do not feed your lettuce just before you wish to harvest it.

If the overlap is too close, harvest your lettuce and then feed it to avoid this issue.

Reason 3 – Too Much Heat

Lettuces like partial shade.

They are a cool season crop, and prefer to be kept at temperatures between 60 and 70 degrees F, rather than any warmer or cooler.

If temperatures rise, your lettuce will stop growing properly and may bolt instead.

Bolting is when your lettuce starts to prepare seeds. A long stalk will form very quickly, and this will turn the lettuce leaves bitter and unpleasant.

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If your lettuce has bolted, you will need to compost it and start again.

You should keep your lettuce cool when the sun is very hot, and put it in a shady place.

Although lettuce does enjoy some sun, the hot weather will quickly ruin the crop.

Partial shade will help to keep the leaves sweet and tender.

If you have your Aerogarden on a windowsill:

  • consider putting up a net curtain to soften the sunlight
  • or move the lettuce elsewhere in very hot weather

Putting a blind down can also help, but don’t block too much light or your lettuce won’t be able to grow.

If your lettuce has been exposed to too much heat, you will need to uproot it and sow fresh seeds, because there is nothing you can do to remove the bitterness at this point.

For lettuce that has only taken on a bit of bitterness, you may be able to get around this by picking it early in the morning.

At this stage, it will have had a full night to recover from the heat stress. You can rinse it, place it in the fridge, and eat it for lunch.

What To Avoid: It is best not to try and grow lettuce in the real heat of summer, as it will often get heat-stressed and bitter even if you try to keep it cool.

Reason 4 – Nutrient Stress

Although feeding your lettuce too close to harvest time is not a good idea, not feeding your lettuce is a bad idea too, as lack of nutrients will make your lettuce bitter.

This is particularly true in an Aerogarden, where the lettuce is dependent on your nutrient additions, rather than gathering the resources it needs from the soil.

Don’t wait before feeding your lettuce if it is time for it to be fed; its quality will deteriorate if it goes hungry for too long.

A day or two shouldn’t make any difference, but if your lettuce leaves are bitter, check when you last fed it, and give it a top up if necessary.

Reason 5 – Old Lettuce

As your lettuce plant matures, its leaves will inevitably become more bitter.

Young leaves are always the best, sweetest, and tenderest, while the older leaves are tougher and less pleasant.

When your plant is getting old, it will quite quickly start to turn bitter, and you may find that even young leaves no longer have much flavor.

If this happens, it is time to strip the plant out and start again.

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Lettuce Aerogarden Yield guide

Most people pick lettuce by just removing a few leaves at a time, and this is a perfectly acceptable way to do it – but eventually, you will need to pull up the whole lettuce.

Use what leaves you can and compost the rest. You can then sow fresh lettuce seeds and get a new lettuce plant to enjoy.

Some people use old lettuce leaves up by cooking them, which removes some of the bitterness.

Mix them in with a soft or sweet green to help mellow the flavor and make them more palatable.

Works Well: You may also be able to soften the flavor by soaking the lettuce in cold water for about ten minutes, and then drying it and putting it in the fridge.


Bitter lettuce is not pleasant, and it can be very disappointing if you have grown it yourself.

However, there are many things that you can do to avoid your Aerogarden lettuce turning bitter, and hopefully this list will have helped you work out how to keep the bitterness down.

If all else fails, strip out your crop and sow some fresh lettuce seeds.

They should grow nice and quickly in an Aerogarden!

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