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Why are my lemons not turning yellow?

A contributing reader, (Marge Adams), recently asked a great question about citrus fruit ripeness. Like many, she would like to know why her lemons are not turning yellow.  Since this issue may become a common dilemma for more people due to climate change, I thought it would be useful to write a short article about it.  

Paraphrased reader question:

‘I have a healthy looking Meyer Lemon tree but the fruit is NOT turning yellow.  Any ideas as to why my lemons look like large limes and do not turn yellow?’

 

Color for ripeness:

Fruit color is usually a great indicator for ripeness.  Crops ranging from peaches to guava typically develop beautiful-rich appealing colors when they are ready to eat.  However, there are some fruits, such as citrus, that may not always change color as expected.

Half yellow lemons at bottom and flowers at top of picture

Half yellow lemons at bottom of the picture and flowers at top of picture

 

Warm weather green: 

As it turns out, many citrus require a temperature dip to stimulate the fruit to change color.  Therefore, when the weather is persistently warm, your lemons may not turn yellow as you would expect.

To complicate things, sometimes only part of the fruit changes color. This finding may be an indicator that it is on it way to ripeness… or that something else is going on.  If the partial color change is sharply demarcated, it might be a sign of sunburn. Sunburn is often (though not always) also associated with areas of browning on the fruit surface. Sunburn can result from sudden intense sun exposure to previously shaded areas after tree trimming or from spraying chemicals such as oils at the wrong time of day.  For more info about appropriately spraying your citrus trees check out my article titled, Citrus Leafminer: Diagnosis and Treatment.

This warm weather green citrus fruit phenomenon is actually a common in some parts of the world.  For example, in the tropics, it is expected that some citrus fruit varieties will never lose their green color the way they would in subtropical climates such as California.  Of course on the other hand, Limes are expected to be green when ripe even in subtropical areas.  For more info on growing limes check out my article titled Bearss Lime Tree Care

Even more surprisingly, sometimes citrus fruit will turn their expected yellow/orange color and then later turn back to green. This may happen if the weather becomes persistently warm again.  I know, that is crazy right?

 

Developing Kumquat fruit showing signs of sunburn

Developing Kumquat fruit showing signs of sunburn.

 

So now how do you determine ripeness?

When your citrus fruit do not turn their characteristic yellow or orange, you need to utilize other indicators for ripeness. I use 3 additional signs of citrus fruit ripeness when my citrus don’t change color on schedule.

Note: Citrus are not known to ripen off the tree like many other fruits.  Therefore, once picked, they are not going to get any sweeter.  This can be a bit confusing because many citrus that are picked green will also change to their expected bright yellow/orange color as they sit on the kitchen counter.

Meyer lemon fruit dropped before turning yellow

Meyer lemon fruit dropped before turning yellow

 

One of the best indicators: 

One of the best indicators of citrus ripeness for me is the firmness of the fruit. This is because citrus fruit typically soften a bit to the touch when they are ripe. Different types of citrus soften to different degrees, so the firmness indicator takes some experience for a particular variety of fruit.

Overall, if your citrus fruit are not turning yellow/green as expected, then it is time to, ahem… to start fondling them.  If the fruit is the softness of ripeness, (the way you remember from experience), pick one and try it out.

Squeeze your lemon

Squeeze a few of your overdue green lemons

 

Another indicator of ripeness: the drops: 

Another indicator of ripeness is that citrus fruit will drop off the tree on their own when ripe (or over ripe).  Now sure, sometimes fruit will drop off a plant on its own when if the plant is stressed or diseased.  Therefore, this indicator is not perfect.

Better still, to identify fruit that will fall off the branch with a gentle tug.  Sometimes just looking at the stalk (where the fruit attaches to the branch) will let you know its time. A stalk will sometimes look markedly angulated or start to pull away at the edges when a fruit is extra ready.

In addition, when you allow the fruit to ripen to the point of dropping on its own you run the very real risk of waiting too long.  Since citrus sweeten and lose their acidic tang over time, waiting to this point may also change the flavor profile.

None the less, if everything else looks good and healthy, when your tree starts to drop the fruit you should pay attention because you might be missing the boat… or your tree might be sick.

A half yellow Meyer Lemon. The stalk is bent and just looks like it wants to be plucked

A half yellow Meyer Lemon. The stalk is bent and pulling away. It just looks like it wants to be plucked.

 

The moving on indicator, flowering: 

Another useful indicator that I have noticed is that many citrus trees start to flower when the hanging fruit is ready or near ready to pick.

This indicator is not perfect either, but it is another one of those things to pay attention to.  If your citrus is flowering massively then it might be cycling through to the next round of fruit.

Ripe meyer lemon and flower buds.2

Ripe Meyer Lemon and flower buds.

 

Wonderful Meyer lemon flowers

Wonderful Meyer Lemon flowers

 

Overall strategy:

Overall, in these warm weather conditions, I tend to utilize all of these markers for ripeness.  It is also important to sample the fruit conservatively because once picked, your citrus fruit will stop ripening.

More Meyer Lemon info:

Prolific Meyer Lemon tree

For great info about how to grow Meyer lemons, check out my article titled Growing Meyer Lemons

You like lemonade? You will love Meyer Lemon Lemonade. Here’s a link to an article I wrote about how to make it yourself at home Meyer Lemonade Recipe

About Thomas Osborne, MD

Dr. Osborne is a Harvard trained Radiologist and Neuroradiologist who loves to share his insight about medicine and gardening.

11 comments

  1. Dear Friend
    Good day, this is frank from china, I am a farmer and I have a lemon orchard, so I am interesting to know is there a equipment to make lemon turn yellow from green color?

    • Thomas Osborne, MD

      Hi Frank
      Thank you for the question.
      There is some debate about if a lemon will ripen off the tree.

      Bottom line is that you can get some early picked green lemons to look more ripe (they may look more yellow), but that does not mean that they will taste any better than they did when they were green.

      Some additional details about my observations below:

      If you pick a lemon early, it may still turn from green to yellow after being picked. The later in the season you pick the better your chances are at getting a green lemon to turn yellow. However, if you pick too early, then they will never turn yellow before they dehydrate/dry up and look really sad.

      Some say that lemons will turn from green to yellow if you put them in a cool sunny spot (like a kitchen counter). However, the longer you do that, the more they will dehydrate.

      Importantly, a lemon turning yellow after being picked is not necessarily a sign that you have a good tasting lemon. Ripening on a tree longer will allow the fruit to get bigger, juicier and tastier. If you pick too early (when green and small), there may not be that much pulp in the inside of the fruit.

      If you are growing at home, it is ideal to wait till the fruit is at least starting to turn a little bit yellow on its own before picking to eat. Ideally, when close to home, what till the lemon is fully yellow before picking.

      However, it is not uncommon for commercial farmers to pick lemons when they are a little bit more green. The main reason to do this is for shipping reasons. A somewhat greener lemon is tougher and can tolerate shipping better/longer. On the same note, a really juicy ripe lemon may not last the shipping time or time sitting on a store shelf. That is one of the reasons why the lemons that you may get at a store are typically smaller, less juicy and less tasty than what you can get in your back yard under optimal conditions.

      Hope this helps,
      Best,
      Tom

  2. We get Meyer lemons in the super market, they don’t keep well so must be bought and used basicaly the same day. I’m used to ordinary comercial lemons so find the flavour of Meyer lemons quite strange, a bit grape fruity which is not so nice for cooking as the tartness is replaced by touch of bitterness paired with a bland sweetness commercial lemon don’t have. Do you think this is normal or only on the new “Improved Meyer” which was basicaly bred and invented from scratch to combate the citrus disease “Citrus greening”. Everyone raves about them but Im not feeling the same enthuisiasm. Maybe they have the originals still?

    • Thomas Osborne, MD

      Hi Anton
      Thanks for your note.

      Yea, Meyer lemons don’t last as long as typical lemons and their skin is more delicate. When I pick Meyer lemons fresh/ripe off the tree, they usually last a week on the counter before they start looking ‘a bit off.’ Perhaps the time on the road traveling from orchard to grocery store gives them the extra limited shelf life that you have noticed.

      Agree, Meyer lemons do taste a good deal different from typical lemons… Most noticeably for me, they are less acid and a bit more fruity as you said. For that, they are not a good one-to-one substitute for typical lemons. Meyer lemons do not seem to do as well for cooking either. But when fresh and ripe, they are delicious in noncooking applicaitons. Therefore, most people I know of use Meyer lemons for non-cooking foods like salads or lemonade (Cooked fish/chicken seems to be better with traditional lemons). I have not noticed ant grapefruit undertone with Meyer lemons; perhaps that may be present if commercial growers pick the fruit too early in attempts to extend the shelf life.

      Thanks!
      Tom

  3. I have a Meyer lemon with lots of fruit. It is small, golfball size, green and getting soft. We have had a very hot summer. /is the fruit rotting? Ripe?

    • Thomas Osborne, MD

      Hi Amy
      Doesn’t sound good. Although its hard to tell what the problem is from here. However, since you mentioned it has been hot, one consideration is that your tree is dehydrated and sucking out the moisture from the fruit to stay alive. Of course could be other things. Cutting some fruit open may help to uncover the cause.
      Best,
      Tom

  4. Hi,
    Is there any way to upload a picture? I cut one open and it is not particularly dry. The tree is in a pot and we water is twice a week.
    Thanks,
    Amy

  5. Hi Tom,

    I live in the tropics and am growing lemons here. The climate here is very hot as you would expect. 8 months of the year the weather is mostly dry while the rainy season lasts for approximately 4 months. Currently, we’re about 6 weeks into the dry season.

    I have three lemon trees on my property and have recently planted another one on a large plantation plot I own.

    I bought two trees at the same time and planted one in full sun and the other in partial shade. Both trees are two years old. The third tree is also planted in partial shade but is only around a year old. I’ve only gotten fruit off of the 2-year old planted in partial shade. It’s doing well, but some fruit are discolored like yellowish-darkish while only about half become the distinctive yellow color.

    Why is this? That tree receives perhaps 3-4 hours of sunlight a day as the rest of the time it is in the shadow of my house. However, given how hot it is here, perhaps too much sun would be the greater problem.

    Interestingly, the tree planted in full sun has never even borne a single flower, let alone a fruit. What is going on there?

    There are no signs of disease and I did a good prune on that tree around half a year ago just in case it might help revitalize it.

    Thanks for your help

    • Thomas Osborne, MD

      Hi “Lemonator”

      Thanks for your question.
      It can be challenging to know the exact cause for plant problems… esp with just a note. However, with the great information you provided, there are some possibilities to consider.

      1. Many fruit trees don’t produce anything… or minimally in the first few years. Since your trees are only a few years old, that may be a factor.
      2. Lemon trees do great in a lot of hot conditions so long as you keep up with their requirements. As you know, they need adequate water and fertilizer. Keeping up with water demands during a prolonged dry season can be challenging. Many people will water smaller amounts frequently, which is not great because this encourages superficial root growth and the moisture evaporates quickly. Ideal watering with the same volume of water happens when you water deeply but less frequently so the water goes down deep. This may require a brim to keep the water in place while it soaks down.
      3. There is come controversy about this, but many citrus growers are strongly against pruning… believing it is hard on citrus trees. This is true in my experience as well. I would avoid pruning citrus trees unless necessary for dead/diseased branches or walkways.
      4. Transplant shock can take a while to recover from. this can set a plant back a season as they try to get established.

      Best of luck,
      Tom

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