How To Tell if a Christmas Cactus Is Overwatered

An over-zealous or overly affectionate plant parent can harm their green babies more than a forgetful plant grower. Overwatering probably kills more plants than watering sparsely, especially in the case of the Christmas cactus. Not many Christmas cactus owners recognize the signs of overwatering and end up showering (the pun is intended) their plants with much more care than needed. 

You can tell your Christmas cactus is overwatered if its roots appear black and soggy, comthe stems are soft and mushy, there is crown rot, or you can smell a foul odor from the soil or any part of the plant. Yellowing or brown leaves, leaf drop, and buds not blooming are also signs of overwatering.

Recognizing the symptoms of overwatering in a Christmas cactus is essential and allows you to take action promptly to save your plant. In this article, I will list the signs of overwatering in a Christmas cactus and explain what you must do if you notice these symptoms.

1. The Roots Are Black or Brown and Appear Slimy

First up, let’s clear the fog around some terms I will use frequently (and interchangeably) in this article. 

Botanically, the Christmas cactus comprises leafless green “stems” made of flat segments. However, these stems function like leaves because they photosynthesize and provide the plant with food and energy. 

Some people refer to these flat segments of the stems as leaves. So, whenever I talk about “stems” and “leaves” in the article, you know which portion of the plant I am referring to. 

Black or brown roots with a mushy appearance are telltale signs of root rot. Root rot in the Christmas cactus is a classic symptom of overwatering. 

A Christmas cactus suffering from root rot has wilting leaves, and displays stunted growth and leaf loss. However, underwatering or exposure to too much direct sunlight can also produce these symptoms. 

So, you must remove the plant from the pot and inspect its roots to confirm root rot. Here’s how to do so: 

1. Wear gloves or cover the cactus with several layers of newspaper before removing the plant from its pot.
2. Hold the pot in one hand and the cactus with your other hand. 
3. Turn the pot upside down and tap the bottom to loosen the plant. 
4. Pull out the plant gently.
5. Shake or brush off the soil to expose the roots.

Healthy Christmas cactus roots are firm and white. A plant with root rot has blackish root tips. If the condition is severe, the roots turn entirely black or brown and look slimy. 

Don’t despair if you discover root rot in your Christmas cactus. You can save the plant if you catch the disease in its early stages. 

Here’s how you can save a Christmas cactus stricken with root rot that still has some healthy roots left:

1. Prune all blackened or brown roots after removing the plant from its pot. 
2. Rinse the remaining healthy roots with clean and lukewarm water.
3. Look for fungal growth and remove the infected parts of the root.
4. Remove dead, diseased, discolored, or mushy leaves and stems, if any.
5. Keep the plant in a warm, well-ventilated spot for a day to let it dry out.
6. Fill a new pot with fresh potting mix.
7. Repot the cactus.
8. Water the transplanted cactus after a day or two.
9. Ensure that you don’t overwater the plant anymore.

Christmas cactus is easy to propagate from stems. While trying to salvage a plant with root rot, it is a good idea to take cuttings from healthy stems and root them. I will explain how you can root stem cuttings in the next section.

Unfortunately, you cannot save a Christmas cactus with extensive and severe root rot. You have to discard the plant.

2. The Stems Are Soft and Squishy

Soft and squishy stems are common symptoms of overwatering a Christmas cactus. 

Cacti have evolved to survive without water for extended periods. They store water in their stems, which often have a fleshy appearance. Healthy cactus stems are plump but firm.

Soft stems may indicate root rot, and you can confirm this by lifting the plant out of the pot and checking the roots. You will have to repot the cactus if there is root rot. 

If only a few stems have turned soft and squishy, and you have confirmed there is no root rot, remove the affected parts of the plant with a pair of sharp and sterile garden scissors or pruning shears. Remove a portion larger than the affected area to ensure no diseased parts remain on the plant.

Do not water the plant for a few days to let it dry. 

You can also take a few stem cuttings and root them to create more plants in case the sick plant does not make it.

Here are the steps for rooting Christmas cactus cuttings:

1. Identify a few healthy stems.
2. Use sharp and sterile garden scissors to take cuttings from the stems.
3. Let the cuttings dry for a few days before potting them.
4. Dip the cuttings in the rooting hormone to speed up the rooting process.
5. Stick the cuttings in a container of perlite or vermiculite or place them in a jar of clean water.
6. Keep the perlite or vermiculite just moist but not overly damp.
7. Keep the cuttings in a warm place where they will receive bright light.
8. Prepare a mixture of one part potting mix, one part sand, and one part orchid bark, or use a commercial potting mix for succulents. 
9. Pour the potting mix into an unglazed terra cotta pot that will soak excess moisture and keep the soil dry.
10. Transplant the rooted cuttings into the mixture. 
11. Keep the cuttings in a warm spot where they can receive bright light.

Henceforth, watch out for overwatering. You can buy a soil moisture meter to ensure your Christmas cactus receives water in the amount it needs to thrive. It is a must-have gardening tool whether you own just a few plants or are a plant hoarder.  

3. There Is a Foul Odor

A foul odor from the soil or any part of the plant is a telltale sign of severe fungal infection and extensive root rot. Overwatering is the most common cause of fungus gnats breeding in the soil and causing root rot. 

Always check for root rot if you smell a strange or offensive odor. If most of the root system has rotted, your plant may not survive. Take stem or leaf cuttings if there is healthy, green, living tissue on the plant. 

If there is no healthy tissue, dispose of the plant and start afresh. Burn the diseased plant instead of dumping it in the compost heap. This prevents the soil-borne pathogens from infecting the compost pile and spreading among your plant population.   

Wash the pot that contained the cactus with warm water or sterilize it before reusing it. This ensures no fungus is transmitted to other plants or seedlings.

4. The Leaves Are Wilting

Limp and wilting leaves can be signs of under- and overwatering. 

Like all cacti, the Christmas cactus, too, can survive in dry conditions with little watering. 

However, the Christmas cactus cannot tolerate parched soil and drought-like conditions. They need more watering than their desert cousins.

So, too much neglect (underwatering) and too much TLC (overwatering) can stress your Christmas cactus. 

The following signs indicate that the limp leaves on your Christmas cactus are due to overwatering:

• There is stagnant water in the drainage saucer below the pot.
• The soil is damp to the touch.
• You have been watering your cactus every day.

Act immediately when you are sure that the wilting leaves on your Christmas cactus are due to overwatering. Do the following:

1. Dump the water into the saucer beneath the pot.
2. Hold back on watering. 
3. Prune the wilting leaves.
4. Check for signs of fungus on the stems. 
5. Check for root rot. 
6. Repot if there are signs of root rot. 
7. Take cuttings to root them if you cannot save the cactus.

5. There Is Leaf Drop

Plants shed leaves when stressed and have to conserve energy and prevent moisture loss through the foliage. Both over- and underwatering can cause leaf drop in Christmas cactus. 

Poke your finger into the soil to check if the top few inches feel dry. If the soil feels damp, the leaf drop is most likely due to overwatering. You can also use a soil moisture meter to check for dampness. 

If you are confident that your cactus has been receiving too much water, stop watering immediately. Dump any excess water that has collected in the drainage saucer.

If root rot has not developed and there is no fungal infection in the soil, your cactus will recover soon and show new, healthy growth.

Follow these best practices when watering your Christmas cactus:

• Ensure the pot has adequate drainage holes at the bottom and that soil clumps do not block the holes. You can check my other article, to learn more about this topic: How to Keep Indoor Soil Moist
• Water only when the potting mix is almost completely dry or the top ½ inch (1 cm) of the soil feels dry.
• Water thoroughly and deeply to ensure the soil is fully soaked. 
• Let the water drain out of the holes after watering before placing the pot on the drainage saucer.
• Throw out the water that may accumulate in the drainage saucer.
• Avoid watering when you notice symptoms of overwatering.
• Cut back on watering after repotting.
• Water minimally during winter, but do not let the potting mix dry out completely.
• Water your indoor Christmas cactus less than what you would if placed outside. 
• Hold back watering a few weeks before the blooming period.
• Keep the soil moderately moist when the buds are about to open and during flowering.
• Err on the side of underwatering. 

6. The Leaves Turn Yellow or Brown

Overwatering can cause the leaves of your Christmas cactus to turn yellow. The yellow leaves eventually wither and turn brown.

Check for signs of overwatering, and cut back on watering till the soil dries out almost completely. 

Yellow leaves can also be a manifestation of pest infestation. 

Nymphs and aphids can feed on the leaves of your Christmas cactus and turn them yellow. 

If you are confident that the yellow leaves on your Christmas cactus are not due to overwatering, examine both sides of the leaves to check for pests. Hose down the plant to wash the insects off the leaves. If the infestation is severe, use Neem oil to treat the plant.

The leaves of a Christmas cactus also turn yellow if the plant is infected with the Impatiens Necrotic spot virus. The plant develops white spots, and the leaves turn yellow. 

Repot the plant using a new potting mix. This should eliminate the virus, and the plant will recover soon.

In rare cases, yellow leaves on a Christmas cactus can be due to a lack of nutrients in the soil. However, this plant does not need too much fertilizer. So, confirm what is causing the yellowing leaves before fertilizing your cactus.

7. There Are Soft Black or Brown Spots on the Stems

Soft black or brown spots on the stems of a Christmas cactus are signs of a fungal infection most likely caused by overwatering. Here’s what you must do when you notice these symptoms:

1. Throw out any excess water that may have stagnated in the drainage saucer.
2. Wear gloves to avoid getting pricked by the spiny cactus.
3. Use a sterile knife or garden scissors to prune the infected portions of the stems.
4. Prune more area than is affected by the black or brown spots to ensure you remove all traces of infection. 
5. Take cuttings from healthy stems for rooting. 
6. Check for root rot.
7. Prune rotten roots, if there are any.
8. Repot.

Sometimes, the leaves or stems on a Christmas cactus can exhibit black or silver spots. This condition is called botrytis blight. It is caused by humid conditions, like when you splash water on the leaves, and they stay wet. 

You cannot save a Christmas cactus affected by botrytis blight. If you are sure the spots are due to blight, discard and burn the plant. 

8. There Is Crown Rot

Waterlogged conditions often cause basal stem rot in cacti. The Christmas cactus is no exception. 

Basal stem rot manifests as brown patches on the plant crown. Because this condition is caused by overwatering, the rot may have spread to the roots. 

However, you can save the plant if the rot is not extensive. Here’s how:

1. Cut the cactus below the brown rotten patch.
2. Remove the plant from the pot.
3. Check for root rot.
4. Cut all rotten portions of the root, if there are any.
5. Pour fresh, well-draining, and fast-drying soil into a new planter.
6. Repot your cactus. 
7. Hold off watering for a few days.

Sometimes, you may water adequately, but the soil does not drain well and causes waterlogged conditions. For instance, dense clayey soil does not drain well.

You can make your own light, airy, fast-draining potting soil or buy a cactus or succulent potting mix at a gardening center or online.

9. The Buds Are Not Flowering or Dropping Off

Christmas cactus buds not flowering or dropping off can be signs of under- and overwatering. 

Overwatering causes root rot. The root cannot take up nutrients from the soil, so the buds do not receive the food they need to bloom. Check for root rot, and repot the plant if the damage is not extensive. 

Conclusion

Unlike its desert cousins, the Christmas cactus does not thrive in drought-like conditions. Neither does it tolerate too much watering.

The key to not overwatering is to be mindful of your plant’s conditions. The golden rule to abide by is to water only when the top few inches of the soil feel dry.