How to Save a Cactus That is Turning Yellow


How to save a cactus that is turning yellow

Has your cacti, one day, gone from a healthy green to a yellow, soft, mushy plant? Then you are not alone! The very same thing happened to me when I had my first cactus, and I went on a research mission to learn why this was and how I could save it.

These days, I have lots of experience reviving cacti and succulents in my job supplying garden centers.

I have also been fortunate enough to speak with expert cacti growers who taught me all their tips and tricks to not only keep a cactus healthy but save it even when it has turned yellow…

Most often, the reason I see cacti turning yellow is usually because of overwatering. Cacti are drought-resistant plants that do not tolerate consistently damp soil. If the soil is too damp and does not dry out between bouts of watering, the cacti develop root rot, which causes the cacti to turn yellow and soft.

My cacti turned yellow in Winter because of a combination of overwatering and temperatures lower than 40°F. Cacti are dormant during Winter, significantly reducing their demand for water and leaving them at a higher risk of root rot due to overwatering.

Another common culprit that doesn’t;t involve watering that I have encountered is that cacti can turn yellow at the top due to sunburn if they are moved from an area of relative shade to full sun without time to acclimatize to a higher light intensity.

This is rare, but I should mention that cacti can also turn yellow and wrinkled if they are not watered often enough or watered too lightly.

To save my yellowing cactus, I replicated the conditions of its native environment by watering when the soil has dried out, ensuring a temperature range of 55°F to 85°F (13°C to 29°C), and removing any diseased roots with a sterile pair of pruners.

Keep reading to learn how to pinpoint the reason for your cacti turning yellow and for my top secret techniques to save it.. …

Why is My Cactus Turning Yellow, Soft, and Mushy?

Whenever I see a soft yellow cactus, the first thing I do is check if the soil is damp and take note of the temperature…

This is because the reason for a cactus turning yellow and soft is almost always overwatering and cold temperatures. Cacti are drought-resistant plants that need the soil to dry out between each watering and prefer a temperature range of 55°F to 85°F. If the soil is too damp and cold, the cactus turns yellow and mushy, which is exactly what happened to my cactus one Winter.

To save our cacti, I always think it is best that we understand how they grow in the wild so we can seek to emulate these conditions in our houses…

Cactus are drought-resistant plants that have specifically adapted to thrive in warm and dry environments with well-draining soils and infrequent rainfall.

To grow a cactus successfully and to avoid the leaves turning yellow (note that I see some cacti turn yellow AND brown due to overwatering), what we need to do is recreate the conditions of the native environment by planting cacti in gritty, well-draining potting soil and only watering when the soil around the roots has dried out.

If the soil is consistently damp around the roots of the cactus, due to overwatering or slow draining soils, parts of the cactus can turn yellow and brown with a soft mushy texture which can indicate root rot.

I. should say that it is not just overwatering that causes damp soil. I often see saucers, trays, and decorative outer pots underneath cacti, which prevent water from escaping from the pot and cause it to pool around the roots and can be the cause of root rot and result in a yellow, mushy cactus.

How I Saved My Yellowing, Soft Cactus

  • I scaled back how often I watered my cactus. If you are watering your cactus more often than once per week, then this is the reason your cactus is turning yellow and soft. Cactus plants should only be watered when the soil around their roots has dried out completely. In my case, this typically takes around 14 days, but I have observed that this can vary according to the pot size, the climate, and the soil drainage.
  • Lift the cactus out of the pot, remove the soil, and inspect the roots for root rot. If your cacti roots are healthy, they should feel firm and thick and look a whitish color (or slightly brown due to the potting soil, which I realize can be confusing), whereas diseased roots are mushy and rotten with a bad smell and brown. I used sterile pruners to cut any diseased roots back to healthy growth. Sometimes, I had to cut the roots back to the base of the cacti. I recommend wiping the blades of your pruners with a cloth soaked in disinfectant (I use hand gel, which works great) between each cut to prevent potentially spreading pathogens from diseased roots to otherwise healthy roots.
  • I re-poted my cactus in new soil. I must insist that you pot the cactus in specially formulated ‘succulent and cacti soil,’ replicating the gritty, well-draining soil of the cactus’s native environment. Normal potting soil holds onto moisture too long for the drought-adapted cactus to tolerate and is often the reason for a cactus turning yellow (a classic mistake!). ‘Succulent and cactus soil’ significantly reduces the risk of root rot from overwatering, and it is available in garden stores or online for a reasonable price.
Succulent soil
This is the succulent and cacti soil I bought online. You can see how gritty it is. In my experience, this is probably the most important factor in mitigating root rot.
  • Always plant a cactus in a pot with drainage holes in the base and empty saucers and trays regularly. Cacti can be planted in various pots if the pot has drainage holes in the base, allowing excess water to drain effectively to prevent root rot. Terracotta or clay pots are my favorites as they have a porous structure that allows the potting soil to dry out more evenly, which suits the cactus’ preference for dryer conditions.

Pro tip: Plant cacti in pots proportionate to their size as larger pots contain more soil and, therefore, a greater capacity for holding moisture, which slows the rate at which the soil dries out and increases the risk of root rot.

To establish when the cacti potting soil has dried out around the roots, I feel the soil at the bottom of the pot through the drainage hole in the pot’s base.

Expert tip: If the soil feels damp, then I delay watering the cactus for a few days. When the soil starts to feel dry, this is the perfect time to water your cactus.

Watering your cactus when the soil has dried out, effectively emulates the natural conditions of -rainfall followed by drought- cycle to which the cactus is specially adapted.

Once you have addressed the causes of why your cactus is turning yellow, soft, and mushy and implemented the appropriate watering schedule, then the cactus can start to recover.

However, if the root rot is extensive it can be very difficult for the cacti to recover, which it was for me, Therefore the best option I had was to propagate my cactus from any remaining healthy growth.

I also cut any yellow, soft, and mushy sections of your cactus off with a sterile pair of pruners, which also helps to prevent the rot from spreading.

Almost all houseplant cactus plants propagate easily from pads, offshoots, and even healthy portions of the stem. My cactus that I saved was a bunny ear cactus (Opuntia microdasys), which had a healthy pad and was so easy to save as it readily propagates.

My cactus
This is my bunny ear cacti that I propagated from a pad 3 years ago and as you can see it has grown many more pads from the original propagated pad…a propagation success story!

Watch this helpful YouTube video for how to easily propagate a cactus plant from pads, cuttings, and offshoots to save your cactus:

Why is My Cactus Turning Yellow in Winter

The reason for a cactus turning yellow in Winter is usually also due to root rot from overwatering. You need to consider that in Winter, cacti are dormant and stop growing due to low temperature and less light, which reduces their demand for water, which makes them vulnerable to overwatering, turning them yellow and mushy.

Cacti are more susceptible to overwatering in Winter because:

  • Cacti are dormant with fewer hours of light and cool temperatures, and they practically stop growing during Winter, so they do not need as much water. During Winter, the roots do not draw up moisture, which means the soil stays moist for longer, and the damp soil promotes the conditions for root rot.
  • With cooler temperatures and less light, the rate at which the soil dries slows down considerably, which means the soil around the roots stays damp for longer and increases the risk of root rot, which turns the cacti yellow.

My Tips for Saving Cactus That is Turning Yellow in Winter

  • Scale back how often you water cacti in the Winter. Exactly how often to water your cacti depends on the temperature of the room, the size of the pot, and the size of the cactus. Typically, I water my cacti every 2 weeks in Winter, but I recommend always feeling the soil at the pot’s base through the drainage holes in the base to check whether the soil is dry before watering.
  • I would move the cacti to an area of more light. The more light, the better during Winter, so I move my cactus to the sunniest window sill in the house.
  • Keep the temperature in the preferred range of 55°F to 85°F (13°C to 29°C) and avoid temperatures lower than 40°F. Most houseplant cacti are native to hot and dry areas, so keep it in a room with the preferred temperature range. This helps to ensure the soil does not remain damp for too long after a bout of watering.

When I lived in my apartment, I only had a southwest-facing window, which was angled, so I didn’t really get enough light from my cactus in Winter.

Pro tip: If, like me, your cacti struggle in the Winter, then I recommend using a grow light above your cacti. I supplement my cacti’s light in Winter, and since then, my cacti have been far more resilient, and they have not suffered from root rot. Trust me, it makes a huge difference.

The steps of saving a yellowing cactus in Winter are otherwise the same steps set out above for saving an overwatered cactus that is yellow and mushy.

This means replacing the soil and checking the roots for root rot. Cut back any diseased roots with a sterile pair of pruners and repot the cactus.

I would recommend propagating any offsets, pads, or cutting from any healthy remaining growth to help save the cactus, as if the root rot is severe, the main cactus stem can be difficult to save. Overwatering is the most common cause of a dying cactus.

Cacti Can Turn Yellow Due to Sun Burn (Ironically!)

Now, I know this seems implausible given that cacti live in the desert, but I can assure you this is true as I have seen it myself!

The reason for a cactus to turn yellow at the top can be because of sunburn. Cacti can scorch yellow when they are moved from low light to full sun without any time to adjust to the increase in light intensity. The sudden increase in light turns the cactus yellow with a scorched appearance.

Most houseplant cactus plants are native to hot and dry conditions and often tolerate full sun.

However, you need to consider that they are often cultivated or stored in the store or nursery before sale in an environment with lower levels of light.

Cactus plants are very adaptable, and what they do is adjust to their environment, even in low light conditions that are less than ideal.

But crucially, it is when they are moved from a shadier location to full sun or even outdoors the cactus is not accustomed to intense blazing sunshine, and the sudden contrast in light intensity is the reason the cactus turns yellow.

Fortunately, I can assure you It is often easy to identify whether sunburn is the reason for your cactus turning yellow (rather than over or under-watering) because the side of the cactus that is most exposed to the sun has the most scorched yellow appearance.

The sudden increase in light intensity is also associated with an increase in temperature, an increase in the rate at which the soil dries out after watering, and usually a decrease in humidity, which can also stress the cactus and contribute to the yellowing. So consider whether a combination of these stress factors is causing your cactus to turn yellow.

How I Save Cactus from Sun Burn

A cactus can adjust to full sun after a period of relative shade. However, the expert growers I talked to told me that they should be exposed to the higher light intensity gradually by locating the cactus in the sun for 20 minutes longer each day over the course of 2 weeks or so.

They assure me that this allows the cactus to acclimatize to the increase in light intensity over a period of time, which prevents the cactus from scorching yellow.

If the cactus has been scorched yellow then unfortunately, I’m afraid it does not turn green again as the surface of the cactus does not have the capacity to recover from sunburn.

However, whilst the sunburned areas of the cactus do not look aesthetically pleasing, they should not necessarily harm the plant (assuming it has been protected from further sun damage).

Your cactus should continue to grow as long as the conditions are favorable (do note that cacti go practically dormant during Winter and do not grow noticeably).

Perhaps the best way I have found of saving a yellow, sun-damaged cactus is to propagate cactus is to propagate it from any offsets that have grown, pads or cuttings of healthy undamaged tissue, which allows you to grow more cacti which can grow a healthy green color.

Why is My Cacti Yellow and Wrinkled? (Underwatering)

Cacti turn yellow because they are not watered often enough or watered too lightly. Cacti require a -soak and dry- watering cycle to ensure the water has reached the cacti’s roots. If the cactus is watered too lightly, the cactus can wrinkle and turn yellow due to drought stress.

I know it is confusing that cacti can turn yellow due to both underwatering and overwatering, but I can report that yellowing is much less likely due to the cacti’s drought resistance, but I have seen it still happen.

A common mistake when caring for cacti is to misinterpret the advice that ‘cacti do not need much water‘ to mean that a cactus only requires a small trickle of water when watering.

What I find is that people water their cacti too lightly, so only the top inch or so of the soil becomes moist, and the water does not reach the roots where it is required.

Cacti store water in their fleshy stem. If there is not enough moisture in the soil available, the cactus draws upon the moisture reserves in the stem. As the cactus depletes its moisture reserves, it shrinks in size, causing it to turn yellow and have a wrinkled appearance.

The cactus also turns yellow with a wrinkled appearance if it is not watered often enough. Factors such as high temperatures, more sun in Summer, and low humidity can also contribute to a yellow, drought-stressed cactus.

My Tips for Reviving a Yellow, Underwatered Cactus

  • Water the cactus with a generous soak so that excess water trickles from the base. This ensures that the soil is evenly moist and the water has reached the roots where it is required. However, you should ensure that any saucers or trays underneath the pot are regularly emptied of excess water to avoid root rot.
  • Water the cactus when the soil feels dry at the pot’s base. Typically, I water my cactus every 2 weeks, but it can depend on your climate, the temperature of the room, and the potting medium. Always feel the soil through the drainage hole in the pot’s base to determine whether the soil is dry before watering. This is important to avoid overwatering your cactus.
  • Keep the cactus in a room that is between 55°F to 85°F (13°C to 29°C). This is the preferred temperature range of most cacti. If the cactus is turning yellow and wrinkled, it can be because it is too close to a source of indoor heat, which dries out the soil too quickly.

I have recovered yellow, wrinkled cacti in as little as 2 or 3 watering cycles. A thorough watering allows the cactus to draw up moisture to replace its depleted reserves in the stem, which should restore its appearance. You can literally see the cactus plumping up after a few days!

I should emphasize that a cactus can recover from a yellowing appearance because underwatering is much easier than overwatering, so always check that the soil is dry before watering.

Will a Yellow Cactus Turn Green Again?

If the reason for the cactus turning yellow is root rot, then no, the soft yellow parts of the cactus do not turn green again and should be cut out of the cactus to prevent the rot from spreading throughout the cactus.

If the cactus has been scorched yellow by sunburn, the cactus does not turn green again. Protect the cactus from full sun and propagate any undamaged offshoots, pads, or cuttings to grow a new green cactus. But sunburn is not fatal, and the cactus can recover.

If the cactus is turning yellow and wrinkled from underwatering, then my cactus turned green again after I watered the cactus generously so that the soil was evenly moist. This helps the roots replenish the cacti’s moisture reserves to restore the cactus’s yellow appearance back to green and healthy.

(Read my article, how to revive a dying cactus).

Key Takeaways:

  • Cacti turn yellow at the base because of root rot due to overwatering. Cacti are drought-resistant plants that require the soil to dry out between each watering. If the soil is consistently damp and the temperature is lower than 40°F, the cactus develops root rot, turning yellow, soft, and mushy.
  • Cactus turn yellow in Winter because of root rot. Cacti are dormant in Winter and need watering less frequently. Damp and cold soil due to overwatering during winter promotes conditions for root rot, which causes the cactus to turn yellow and mushy.
  • Cacti can turn yellow at the top due to sunburn if they are moved from a relatively shady area to full sun without time to acclimate to a higher light intensity level. The sudden contrast in light conditions can scorch the cacti yellow.
  • Cactus plants can turn yellow and wrinkled if they are not watered often enough or watered too lightly. Cacti store water in their stem. If it’s not watered often, the cactus depletes its moisture reserves, causing the cactus to turn yellow and wrinkled in appearance.

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