Why Is My Cactus Turning Yellow?

You’ve wondered why your cactus turning yellow. You’ve been taking care of it and from one day to the next, it dawns yellow. I’ll give you some helpful tips so you can diagnose what’s happening to it.

Why Is My Cactus Turning Yellow?

  • Burn from too much sun exposure
  • Etiolation from lack of sunlight
  • Rot from too much water
  • Dehydration from lack of watering
  • Burn from environmental shock
  • Discoloration due to lack of fertilizers
  • Burn due to very cold temperatures
  • Diseases

We will be analyzing each of these factors so that you can find out exactly how to find out and get to work to recover your yellowing cacti.

Cactus Turning Yellow Too Much Sun Exposure

Most cacti indeed require many hours of light, however not all need the same amount. We will have to observe if it is suffering discolorations to be able to judge how much sun it needs.

Cactus exposed to too much sun become yellow, lighter green and some even become whitish.

In these cases, we should relocate them to shady places for a few hours and monitor their condition.

Cactus burned by the sun, are usually those that were in more sheltered places and from one day to the other were exposed to sunlight. As they are not used to the full sun, they get burned.

If one decides to change the place of a cactus, or it is a recently bought cactus that in the nursery was under a shade, we will have to make a gradual change of place. This way our cactus will get used to the sunlight little by little, and will not get burned.

cactus turning yellow too much sun exposure

Cactus Yellowish Color Due to Etiolation from Lack Of Sunlight

Cactus are not plants that need the little sun or like to live in the shade. With a lack of sunlight, they begin to change their green to lighter green or yellow.

A cactus that is indoors without light will suffer etiolation or have its epidermis weakened by lack of sun. Etiolation causes the cactus to elongate in search of sunlight, yellow, and weaken. With etiolation, the cactus loses part or all of its chlorophyll pigments, hence its yellow or even whitish color.

All these symptoms are telling us that the cactus needs sunlight, but be careful not to bring it suddenly into direct sunlight, because it will burn.

In these cases, the cactus should be habituated, little by little, to the sunlight it needs and closely monitor its improvement.

Cactus Turning Yellow Too Much Water

Excessive watering causes cacti to turn yellow, this is because the roots suffocate and the fleshy body rots, which can kill the plant.

A cactus should be watered every 15 days and its substrate should not always be wet, for this we should always check before watering the state of the substrate.

If your cactus is turning yellow due to rotting, you should repot it into a new pot with a porous substrate that has good drainage, placing a good gravel base. Perhaps the reason for the rot is very compact soil or substrate.

If the rot is in an advanced stage, we will have to resort to something more drastic. Cut below the yellow spot to be sure to remove all the rot. You should cut down to where the center is healthy. The healthy part of the cactus that is left, let it dry in a bright place but not in direct sunlight for a week, and then plant it.

Remember that the cuts must be made with a sharp instrument and disinfected with alcohol for example. After each cut, disinfect again, to make sure that you will not pass any disease to the healthy part.

cactus turning yellow too much water

Cactus Yellowing from Dehydration Due to Insufficient Irrigation

Cactus that suffer from lack of water, to survive, consume all the stored water they have. This stored water is found in the fleshy body and works as a reserve for these cases, but if they lack water is prolonged in time, it will begin to change its color and wrinkle until its water reservoir ends and it dies.

A simple solution is to always check the humidity level of the substrate. If it is dry, you should water it, but never to the point of flooding because its roots will rot. To avoid waterlogging the succulent, the substrate should be light (Soil for Cactus Order here).

If the cactus is already in its final stage and you see it dehydrated and wrinkled, one way to save it is to repot it. Remember to do it carefully because it is really weak. The new substrate and the measured sunlight should recover it.

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Cactus Yellowing Due to Environmental Shock Burns

Generally, cactus recently bought in nurseries or hypermarkets have not been in full sun, so they are sensitive to its rays. We will have to acclimatize them little by little.

It is customary to think that cacti, being desert plants, can withstand direct sun and high temperatures, so when we buy them we make the mistake of taking them from a place where they are sheltered, to a place with full sun and that is when we burn them.

cactus yellowing enviromental shock burns

Cactus Turning Yellow Due to Lack of Fertilizers

The yellowing of our cactus is accompanied by deficiencies in growth. It can be slower or irregular growth.

Fertilizers stimulate the growth of our cactus by providing micronutrients and amino acids. This prevents cacti from losing elasticity, yellowing, and softening.

It is quite common for cacti to discolor due to lack of fertilizer because cacti require drained soils and these have low organic matter. If we do not fertilize our cacti regularly they will have a lack of macronutrients and will turn yellow (Order Fertilizer here).

Renewing the substrate every year helps, not only to improve the soil structure but is also an extra supply of nutrients. But it should always be accompanied by fertilization.

Fertilization of cacti to be effective should be carried out in spring and summer. It is important to do it once a month and with your cactus watered beforehand.

Cactus Turning Yellow Due to Very Cold Temperatures

The freezing temperatures cause disorders in our cactus, causing burns or burning them completely if the cold is too intense.

A good way to protect them is to cover them with anti-freeze blankets or some plastic you have at home, which will trap the hot air and will not let the cold burn them.

If it is in a pot, the idea is to take it to a place where it is sheltered from the intense cold for a few days until the frost season passes.

cacti cold temperature

Cactus Yellowing Due to Diseases

Our cactus can turn yellow due to diseases. The most known is the fungus, which is usually formed by excess moisture. In this case, repotting it to a new pot with a good substrate and drainage should be done so that the plant can recover. A fungicide should be applied, specific for fungi or we can make one at home. This will allow us to control the infection and prevent it from spreading.

Another disease that cacti can get usually occurs when we prune with elements that are not properly disinfected or we make a cut and do not disinfect again to make the second cut, thus carrying the disease to the healthy part of the cactus.

A bad cut or a cut that was produced by a fall can also be prone to make our cactus sick. It is advisable to put cinnamon in each cut that we leave on the plant. Cinnamon is a mild fungicide, but of great help in these cases.

Why Is My Cactus Turning Yellow? – Final Conclusions

As we have seen, cactus change their color due to health problems. Many times several of these factors can come together, such as too much sun and lack of water or rotting due to a compact substrate or poor drainage.

The important thing is that we can identify each one and start working on its recovery. Of course, you will be left with scars that will remind you of the blunder but you will have learned not to make the same mistakes in the future.

Learn more about How to Grow Cactus from Seeds and How to Take of a Cactus for Beginners.

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cacti yellow final conclusions
About Henry Morgan

We are the Morgans, Henry, and Julia, both agronomists from the University of Michigan, where we met. We are experts in putting our hands in the soil and developing organic foods and improving production processes for decades. Likewise, we have worked for companies such as Mondelez International, BASF, Monsanto, etc. currently in our role as science writers for TheGardenStyle.com as well as advisors in promoting large scale food growing in urbanized areas. In this website, we share what we are most passionate about, gardening and farming. Enjoy and see real photos on our website.