17 Reasons Why Your Saguaro Cactus is Turning Yellow

Saguaro cactus is a unique and beautiful plant in the Sonoran desert. Indoors saguaro gets more care but turning yellow may hurt cacti lovers. In this article, I am going to share 17 reasons why it turns yellow.

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1.Underwatering 

Don’t misjudge your saguaro that it is a desert plant and it doesn’t need any water. It is not a holy cow.  It needs water. If goes many days without water, the saguaro starts to turn yellow. But, too much or too little both are extreme. Extreme never sustain. So don’t be extreme to your saguaro.
With little or no water in the soil, fungi and bacteria are also likely to grow, which might eventually kill your saguaro cacti. 

2.Overwatering

Some keynotes indicate that you are spraying too much to your saguaro.

1. Yellow shade: your cacti leaves turning into yellow because you are probably pouring too much water into your saguaro.
2. Darkening of leaves: overwatering your saguaro turns its leaves into the dark. At the end, it may end up to start rot.
3. Too much watering halt the air flow to the roots, and turn the leaves yellow.

The Saguaro requires about 10 inches of water annually.

4. In growing and blooming season, it starts to use its reserve water from its stem, and leaves which makes it look like shrievel. The plant may also turn yellow, and this is usually visible from the parts closest to the soil going upwards.
5. In winter dormant season, overwatering can  damage the saguaro cactus, and turn it yellow.

Until the soil is fully dry don’t pour water. And buy a moisture meter to make sure the moisture level in the soil.

As described University of Arizona Campus Repository, It is important to find a compromise between providing enough water and preventing over-watering. Water should be applied only when the soil surface begins to desiccate.

3.Not Enough Sun Exposure

1. Light is life. But too much light can be detrimental to your saguaro cacti.
2. Don’t attempt to put your saguaro to place on the windowsill or terrace where it gets direct sunlight. Don’t burn it. It will turn your cacti yellow.
3. Regularly follow up with your cacti. Is it getting enough light or not?  Is it turning from green to yellow?
4. Is your saguaro growing towards the window or sun direction? If yes, it means that your cacti is getting  less than it needs.
5. As per my experience, I recommend you to put your saguaro at south or west-facing.

4.Overheat

In summer, it’s really tempting to put a cactus outside in your garden. They can tolerate high temperatures, unlike humans. At  100 F (38 C), the Saguaro Cactus (Cereus giganteus) produce its large flowers. 

In the case of indoors, because of cooking and breathing the house humidity is high. Besides, closed windows and doors, unlike desert fresh and moving air, cause raise the humidity of the house.  The excess humidity is absorbed by the saguaro and turns it to yellow color.

5.Frost Damage

However, in wintertime, it’s important to keep them somewhere warm! Don’t let the temperature be below 15 degrees Celcius.  In order to maintain your cactus’ health and growth period throughout the year, don’t let them get cold.

Extremely low temperatures may cause a loss of turgor in saguaros.

University of Arizona

6.Lack of Minerals

Wherever there is some cause, there must be some effects. It can be in your life or can be in your plants. 

Don’t think that only human needs minerals, but your cactus also need minerals like food.

Insufficient minerals in saguaro show a yellowish color in the leaves and stems.

Saguaro demands mineral-enriched soil and fertilizer regular basis. This is the foremost requirement for a healthy saguaro, especially in spring and summertime.

Cactus growth is largely influenced by various minerals and trace elements. They are found in plant nutrition.

• Lack of magnesium and iron turns your saguaro into yellow.
• lack of phosphorus slows down growth, the plant turns pale;
• with a lack of calcium, the cactus root does not grow well.
• with a lack of nitrogen, the cactus stem will slowly grow;

Some more minerals deficiency also retard the growth of saguaro. These are lack of boron, copper, iodine, and chlorine. 

Roughly 18% of the dry mass consists of the biomineral weddellite (CaC2O4·2H2O). The C in the weddellite derives from atmospheric CO2 via photosynthesis.

7.Soil Type

Saguaro can prosper in a range of well-drained soils containing

1. Sand, 
2. Silt,
3. Loam,
4.  Including gravelly and
5.  Rocky soil. 

Saguaro doesn’t grow well in poorly- drained soil. The saguaro is a rare plant and it demands well-nurtured soil also.

8.Need a Transplant to another Soil

Saguaro is a very tough, pain-staking, resistant bearing plant. It doesn’t expect normal care from you. That doesn’t mean that it doesn’t need any care.

Survival is one thing, but growth is a much bigger issue for a saguaro.

If your saguaro is growing many days in the same spot on the same substrate,  it may not grow, went to yellowish, and lose elasticity of the outer layers of the skin. So why late to transplanting to new soil and new pot?

Make sure that your new pot is a little bit larger than the old one.

1. The container, I used,  is filled with a drainage layer. It’s composed of two materials-expanded clay or gravel.
2. Then a small layer of soil is poured on top.
3. Angling the cactus so that its roots evenly wrap around the circle of the pot, the final product will come out more beautiful overall.
4. The pot then gets filled with soil
5. If you are transplanting a large specimen, make sure to shake the soil off of it thoroughly by hand; cover it with gravel or clay.

9.Fall from Right Fertilizer 

A mixture prepared at home is also effective, with the following composition :

• 2.5 liters of water;
• 0.5 g of calcium sulfate;
• 1 g of potassium nitrate;
• 0.25 g of ferrous sulfate;
• 0.25 g of superphosphate.
  

From my own experience, I can say that don’t use ready-made soil mix because it has too much nitrogen.
In particular, the shoots lose their normal color due to a lack of potassium, calcium, nitrogen, and phosphorus.
Use your own handmade fertilizer during high growth season. Don’t spray fertilizer during the saguaro’s dormancy period. Again, nothing will return from pouring fertilizer at the damaged roots.
A saguaro lover should keep in mind that after transplanting and rooting using fertilizer will harm your cacti.

10.Pests

Proper treatment at home rarely can attack the saguaro cacti by pests. Pests are two types- one attacks into the roots and another affects fleshy stems.

As stated by UA Cooperative extension, the Young seedling saguaro is delicate and lacks strong defensive spines. They can be consumed by many kinds of insects, birds, and rodents, or damaged from rummaging and trampling.

When this happens, your cactus will begin to turn yellow as a way of showing its stress.

Though most cacti don’t have a significant problem with most pests, saguaro cacti have their own pest nemesis. 

The most harmfulness of insects can be determined by the yellowed fleshy stem, whitish bloom, various spots and depressions, and a thin cobweb.

Bird-excavated cavities are a potential entry point for bacteria. Bacterial necrosis is associated with most saguaro deaths.

The most common pests of  saguaro cacti are:

• aphid;
• spider mite;
• mealybug;
• scab;
• root felter.

11.Placement

Don’t place your cactus in a place where there is not enough sunlight. It doesn’t mean that you have to place your saguaro getting direct sunlight to be roasted.

A place where not too much or too little sunlight is available. 

A Saguaro needs to be planted in the same compass position so it will have same sun exposure as it had prior to transplanting to avoid sunburn. 

12.The Water Used

Although the idea of watering your plant with tap water may seem like it’s not a harmful thing, you should know that this is not always the case. If you have softened water and have inadvertently used it on your cactus, then there may be salt crystals forming on the soil surface which will eventually destroy the soil’s ability to retain moisture.

13.Environmental Shock

If your saguaro is starting to develop a yellowish tint to the leaves and showing drooping, it may be because of an environmental change. So what should you do?

1. Watering as per its daily requimments.
2. If not yellowish color turn to green, then do repotting.

14.The Pot is Too Small

The more stress on your saguaro, the chances to grow yellowish in color. But the reason behind that is the pot is too small. 

Warning:  Don’t use a too big pot. It will again rot the roots of the saguaro. Too much big pot will hold more water.

15.Physiological

Not only that saguaro turns yellow for over/underwatering,  minerals, extreme sun exposure, etc, it may occur also for physiological reasons also.

Possible physiological problems in saguaro are:

• Corking: it’s an aged issue of saguaro. The tough skin in the lower part of the saguaro stem. Luckily, at home with proper care it is saved from corking, saving your saguaro from lack of decorativeness.
• Diseases: called jaundice. If the cactus stem turned yellow, became soft or dense, but decreased in size, this does not necessarily indicate an infectious disease.
• Sunburn: In early spring or summer, in the heat, direct exposure to the rays leads to the formation of yellowness on the stem.

16.Diseases

Chlorosis: is a disease of yellowing saguaro cacti from green leaves. It happens due to a lack of chlorophyll in saguaro stems- The Morton Arboretum

One of the main problems concerning chlorosis is that it upsets the mineral balance( high PH) in the soil. But the more  reasons for chlorosis are: 

1. poor drainage, 
2. damage to the root system,
3.  unsuitable soil, 
4. Infections,
5.  Pests

The mineral imbalance and the above reasons deter the photosynthesis and production of chlorophyll. So the sum-up results of these are yellowish color in your saguaro.

 In Chenopodium quinoa, it caused systemic infection showed as chlorotic veins and intervenal yellow spots, stated in the Mexican Journal of Pathology.

17.Rhizoctonia or Wet Rot

Wet rot or Rhizoctonia is a disease that can turn your saguaro into yellow color.

As starting from the root, but reaching the tipping point of the cacti may cause death also.

Don’t let this disease happen this incident to your lovely saguaro but how?

1. Immediately cut off the affected parts.
2. Replace the old soil with fresh substrates.
3. If necessary, remove the top, root, even do grafting onto the rootstock.

Related questions

How do you know whether you’re providing the right amount of water for your cactus?

• Using your point  fingers
  If your pot seems dry, dig down into the bottom of the pot with your finger until you feel moist soil. If there is just some stored water left in the soil, give it a quick rinse.
• Use a moisture checking device
  You will also use an electronic moisture meter to help you make sure that your soil has enough moisture.
• Use bamboo stick
  Insert a bamboo stick in your pot to check whether the soil is wet or dry. From the stick, you can decide whether you water or not.
  
  Make sure that your soil is well-drained, gravelly, rocky,  and sandy. All other chemicals composition in the soil mix should not be such types that hold water.

Is Your Saguaro Cactus Cramped?

Observe yout saguro mother. Is it producing offshoots? Is it crowded with too many babies?
Make sure that mother saguaro gets more micronutrients to grow wealthily. Repot the babies as soon as possible. Otherwise, it will cause get yellowing the saguaro. Simultaneously, do the repotting for your main saguaro also.

Is Your Cactus A Yellow Variety?

Are you sure about the variety of your cactus? Some saguaro is yellow in nature. Why so much thinking when there is nothing wrong with your saguaro.

Why can a saguaro turn yellow at the base?

Yellowness at the base will occur for the following reasons:

1. Direct contact sun rays to saguaro base.
2. Micronutrients deficiencies in the soil substrates.
3. The roots are overwatered and getting started to rot on the way.
4. The flowers change color on one face while the other face turns to black spots.

When is it the norm?

What’s wrong with skin when it gets sagged over older age. So can be true for your saguaro also. With the older age, your saguaro cacti start to wear and tear. And, its lower part starts to turn yellow.

In the winter season, saguaro turns yellow. Lack of sufficient sunlight and humidity, it is very natural to get yellow.

Is it necessary to isolate a yellowing flower from other plants?

Yellowing of saguaro cactus flower is not a viral disease that you have to put unhealthy saguaro into quarantine. Just proper sunlight, soil, watering, and environment are enough to return your yellow saguaro to green. 

The apparently sick saguaro will not impose any risk on your healthy saguaro.