3 Reasons Why Your Lemons Are Brown Inside

Have you got a lemon that has turned brown and looks unpleasant inside? This is a surprisingly common issue, but you might not be sure what causes it.

Quite a few things can cause lemons to turn brown inside, including deficiencies and pests. Working out what has caused the problem might help you to decide whether you are happy to eat the lemon or not.

In this article, we’ll look at the 3 main causes of brown spots inside lemons, as well as some tips on how to solve these issues.

What Makes A Lemon Go Brown Inside?

lemon brown inside

Cutting open a lemon to find the inside has gone all brown and unappetizing is not an enjoyable moment, and you might wonder what has caused the browning and whether it makes the lemon unsafe to use.

There are a couple of potential causes for lemon brownness, including:

  • Pests
  • Mineral deficiencies
  • Boron deficiencies

Any of these could be the cause of browning inside your lemon, so let’s explore them all in more detail. Note that you may not always be able to tell what has caused a lemon to go brown inside, but understanding more about the potential causes gives you a better chance. If you grow your lemons, it’s particularly important to take the time to check this.

Reason 1) Pests

One of the commonest causes of brownness inside lemons is the pests that they suffer from. One species is especially known for causing brown spots inside lemons, without visibly harming the surface of the fruit.

This is known as the spined citrus bug, and it pierces the lemon’s rind, driving its mouthparts into the fruit so that it can suck out the juices. This compromises the protection that the rind usually provides the fruit with, and leaves the inner part vulnerable to decay.

This damage may stay localized, or it can spread out from the point at which the fruit was pierced, causing browning as the cells oxidize. Sometimes, attacks by spined citrus bugs will cause patches of brown stickiness on the outside of the lemons too.

You may also find that your lemons fall off the tree before they are fully ripe, which can be particularly annoying. Spined citrus bugs aren’t easy to control, but you can reduce their numbers by manually removing the adults from the tree.

This is labor-intensive, but it’s one of the most effective ways to get rid of insects, especially if you wish to avoid pesticides. Getting rid of the adults will help to break the lifecycle, but you will need to be vigilant and get rid of them before they have the opportunity to breed.

Reason 2) Mineral Deficiencies

Often, brownness inside lemons is as simple as a mineral deficiency. If the tree does not have access to the right vitamins and minerals when it is developing its fruits, there is a risk of the fruits developing brown flesh inside.

The lemon may not show any signs of having a problem on the outside, because the deficiency affects the fruit as it is growing, and does not need to access the flesh from the outside. It is, therefore, possible for a lemon that looks good externally to have brown patches within.

This can be very frustrating, and if you are growing your lemons, you might want to do a soil test to see if there is a deficiency that could be causing the brown flesh inside. This is particularly worthwhile if lots of the lemons seem to have this problem.

If you do discover that mineral deficiencies are causing problems in your lemons, you will need to feed your lemon trees to resolve the issue. You should then find that the next year’s crop is much better, and the brown flesh has disappeared.

Reason 3) Boron Deficiencies

Boron deficiencies are a type of mineral deficiency, but it’s worth listing them separately because they are common and certainly something that you should test for if your lemons are brown inside.

Again, you can test for a boron deficiency pretty effectively by using a soil test kit. Boron is critical for many parts of the fruit’s growth, including the flowering stage, the growth of the pollen tube, and the fruiting.

If your lemon tree is not getting enough boron, you are very likely to see the lemons turning brown in the centers. Fortunately, this can again be rectified by increasing the amount of boron in the soil around your tree before your lemon fruits again.

You can do this by adding about 4 teaspoons of borax to every 1000 square feet. Don’t add more borax than this, because it can be toxic in high quantities.

Can You Eat Lemons With Brown Inside?

If you’ve found a lemon with a brown patch inside it, you should inspect this brown patch carefully before deciding whether to eat the lemon or not. First, check that there are no signs of mold appearing on the flesh, as this would indicate that it was not safe to eat.

Next, smell the lemon carefully. If it smells fresh and sharp, it should be okay to eat. If it smells musty or unpleasant, there is a chance that the fruit has gone off, and it should be discarded.

On the whole, whether they are caused by nutrient deficiencies or pest damage, brown spots inside a lemon are not dangerous. They may make the lemon drier and less pleasant, but they shouldn’t hurt you.

However, it is always a good idea to check whether or not a fruit smells and looks okay before eating it, even if the flesh doesn’t appear to be damaged. Inspect brown lemons with care before you decide to eat them.


Brown spots inside a lemon can be annoying, but they aren’t usually a major issue. You can cut the brown part out or use it in your recipe, and most of the time, there is no risk. However, get rid of lemons that have turned moldy, slimy, or black inside.