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10 Reasons Behind Cactus Turning Yellow

Though the Cactus is hardy succulent, yellowing and browning stems in the plant are no exception. The potted Cacti are more prone to these problems as they have not hardened off enough. 

Generally, Cactus turning yellow shows watering issues, improper light, temperature stress, nutrition deficiency and overfeeding, pests and diseases infestation, wrong soil, and pH, etc. 

Once the Cactus gets yellow completely, you have only propagation as an option. So, read this article to fix the early signs of yellow Cactus. 

Why is my Cactus Turning Yellow? (Causes & Solutions) 

Under stress, Cacti and Succulents often change their color to red, yellow, brown, and purple.

Once your Cactus is discolored or yellowed, there’s no going back, and you cannot revive it back to green. However, you can always save them from dying. 

Let’s learn more about the reasons for Cacti turning yellow and also find out some practical solutions to treat them. 

1. Overwatering Issue

Cactus is a Succulent that stores water in its trunk, thus requiring minimum watering.

The soil gets over-saturated when you frequently pour water. 

Soggy soil deprives the roots of Cacti of air and encourages anaerobic activities. Such activities invite bacterial and fungal growth, causing root rot. 

Excess watering is detrimental to root rot causes drooping and yellowing.
Excess watering is detrimental to root rot, causing drooping and yellowing.

Thus, if your Cactus has turned yellow, it has probably undergone root rot. 

Practical Solutions  

  • Cut off the parts that are yellowed or discolored. 
  • Let the soil dry up entirely, and avoid watering during this period.
  • If the plant is excessively yellowed, you can dig into its root and check for root rot conditions. 
  • Cut off dark mushy roots, if any, and apply some fungicides. Leave the Cactus for a day or two until the root dries up, and then repot in a new potting mix.
Water your Cactus once in 10-15 days during summer and every 20-30 days during winter.

However, watering requirements change according to climate and environmental condition, so water your Cactus only when the top 25% of the soil is dry. 

2. Drought Condition

If you delay irrigating your Cactus only once a month during growing seasons, the plant gets underwatered. 

Water deficiency can hinder nutrition uptake and other physiological functions, so provide your Cactus with plenty of water.

When it is deprived of water, its leaves and trunk shrink, turn yellow, and the tiny baby Cactus sprouts fall off. 

Practical Solutions

  • Check the soil; if the top portion is dry or cracked, water it immediately.
  • The best way to revive it is to water from the bottom method. Submerge the pot in a pool of water and leave it until the topsoil is saturated with water.
  • Move your Cactus to a place where the sun is not intense, as it can be a potential cause for the quick drying up of soil.
If the soil is pulled away from the pot, push it towards its surface to prevent water seepage from the sides of the pool.

3. Intense Sunlight Exposure

Although Cacti thrive in dry and hot climates in deserts, you should still protect them from high-intensity sunlight.

Baby sprouts or Cacti can easily get scorched and turn yellow under the intense sun as they are tender.

Besides, harsh sunlight causes quick evaporation of water present in the soil. So, if you have placed Cactus in a sunny spot, it demands more frequent watering.

However, it might turn brown and yellow if you fail to meet its water requirements.

Practical Solutions

  • If the parts are severely damaged, get rid of them, as they spoil the looks of your Cactus. 
  • Consider placing the plants near open east or north-facing windows within a distance of 1-2 feet, where they can experience some humid air.
  • Use a drape or light curtain to protect the harsh midday sun from scorching your indoor Cactus. 
Move your plant to a location where it receives morning and evening sunlight. 

4. Low Sunlight Exposure

In their natural habitat, Cacti grow in deserts where they experience a good amount of sunlight, so you need to provide them with enough light.

Succulents like Cactus and Jade require direct sun exposure of 10-12 hours daily. 

When deprived of enough light, their photosynthesis and other physiological functioning are disturbed; as a result, they turn yellow. 

Practical Solutions 

  • Immediately move your Cactus to a well-lit area where it experiences full sunshine. 
  • Avoid moving your Cactus from a brighter to a medium light or darker area. 
  • Alternatively, you can use artificial light, a fluorescent tube producing about 3000k light for about 6-10 hours at a distance of about 6-12 inches, to supplement optimal light for Cacti. 
Move the Cacti outside during winter, where they get sufficient sunlight. 

5. Excess or Deficient Fertilization

Though Cacti are not heavy feeders, they need a balanced fertilizer (diluted to half) to thrive. 

Depriving Cacti of essential nutrition prevents them from getting energy, and they start degenerating, usually starting from yellowing and browning.

Similarly, overfertilizing the plants builds up salt in the soil, which causes the burning and yellowing of Cacti.

Practical Solutions 

  • Most experts state that fertilizing Cactus once a year is ideal. However, you can fertilize them twice, once before the advent of spring and the next during spring, to boost healthy growth.
  • Also, you can follow a nursery method called fertigration to fertilize your Cactus. 
  • Avoid fertilizing Cacti during winter as the plant becomes dormant. 
To wash off excess fertilizer, drench the pot in tepid water for about 15-30 minutes. This helps to flush out excess salts through osmosis and prevent further yellowing. 

6. Wrong Potting Mix 

Cactus likes chunky and sandy soil that drains water thoroughly, holding only optimal moisture.

Hence, if your potting mix retains water for a long time, your Cactus is probably experiencing root rot issues.

Besides, soil pH plays a vital role in absorbing nutrients and toxins.

cactus completely yellow
Improper soil can make the plant pale outside.

So, if the soil pH is not balanced, nutrition deficiency or absorption of harmful chemicals might lead to the Cactus turning yellow.

Practical Solutions

  • Use chunkier, sandy, porous, light soil mix instead of regular potting soil. Succulent mix like Miracle-Gro is excellent for Cacti.
  • Maintain slightly acidic soil pH between 5 to 6.5.
  • Add pine bark, mulch, and organic compost to acidify the soil.
Soil Recipe for Cactus: 3 parts potting soil+3 parts coarse sand+1 part perlite or pumice + 1 part pine bark (optional)

7. Temperature Stress

The ideal temperature for Cacti is anything that hovers around 45-85°F. 

If your area experiences hot summers and warm winters, your Cactus will hit dormancy during summer and grow during warm winters or the rainy seasons.

Meanwhile, the opposite will happen for places experiencing cold winters and warm summers.  A temperature lower than 40°F and above 90 °F harms your Cactus.

All these extremes cause stress in Cacti, turning them yellow and brown and possibly dying. 

Practical Solutions 

  • Increase humidity and watering frequency during extreme heat to help Cacti cope with water loss. 
  • Avoid exposing Cacti to the direct sun of midday during the hot summer. 
  • To prevent Cacti from a cold, bring the plant indoors at night during winter. 
  • You can also place a heating mat underneath the plant to protect it from the cold. 
  • Alternatively, you can place your Cacti in the greenhouse or terrarium place or use a frosting bag to prevent cold. 
Low-temperature cause defrosts of the cellular water, thus damaging all physiological functioning of plants. In contrast, extreme temperature causes excess evaporation that compels Cacti to shrink.

8. Pests Infestation

Pests like mealybugs, scales, and spider mites can also cause yellowing, browning, and black spots on Cacti.

These pests suck the sap out of the plant and drain the plant out of nutrition, leading to the Cactus turning yellow. 

You can easily spot the infestation signs through brown spots. 

Practical Solutions

  • Firstly, quarantine your Cactus from other plants to avoid spreading the disease. 
  • Apply Neem or commercial horticultural oil over the plant to mitigate pest attacks. 
  • Alternatively, you can use a cotton ball dipped in about 75% diluted isopropyl alcohol and dab it along the pest-infected parts.
  • You can handpick these pests using tweezers if their numbers are less. 
You can apply pesticides on the Cactus every two weeks to prevent infestation. 

9. Disease Problem  

One significant problem for the Cactus turning yellow is chlorosis, which generally occurs in Cacti because of insufficient nutrition, underwatering, overwatering, etc.

The first sign of chlorosis is turning the Cactus into a lighter green with speckles that, in severity, turn yellow or brown.

Similarly, fungal disease like  Cephaleuros wilt, caused by the fungus Verticillium dahliae (Vd), is also responsible for Cacti turning yellow.

Practical Solutions

  • Cut off all of the affected parts to prevent the further spread of diseases. 
  • To treat root rot, cut off mushy roots, apply fungicide and repot in a new potting mix. 
  • To remove chlorosis, repot your Cacti into a new succulent potting mix and address watering issues.
Apply fungicides on your Cacti every 1-2 weeks to prevent bacterial or fungal diseases.  

10. Exposure to Chemicals

Some chemicals, such as chlorine and fluorine, found in water or fertilizers, can create toxins in the soil. 

Also, when you use harsh water rich in salts and other toxins, it gets stored in the soil. 

Accumulation of such salts and toxin build-up changes the pH of the soil from acidic to alkaline.

Incorrect soil pH means less nutrition absorption and increased toxins absorption by Cacti, causing discoloration and yellowing. 

Practical Solutions 

  • Flush off all the toxins and salts by submerging the Cactus pot in rainwater for 15-30 minutes. 
  • Check your water for salt and toxin levels, and use it only after it is free of harmful chemicals and salt.
  • Take Cactus from such contaminated places, including sprinklers used on lawns.
  • Alternatively, you can use filtered water to hydrate your plant.   

From Editorial Team

Grow No Fuss Cacti 

If you don’t want to get stressed about your succulents, grow Gymnocalycium, Mammillaria, Echinopsis, Hatiora, and Rhipsalis plants. 

You can grow these Cacti outside in the spring and summer and bring them indoors during winter.