In this article I will cover everything you need to know about watering a christmas cactus plant. I also touch on the topic of underwatering and the signs you can expect to see in an underwatered christmas cactus. Christmas cactus, like all succulents, is susceptible to root rot and other problems caused by overwatering so I cover this topic in detail also.
- Christmas cactus watering guide
- Does Christmas cactus need humidity?
- How to water christmas cactus
- Do you water christmas cactus from the top or bottom?
- How much should a Christmas cactus be watered?
- Overwatered vs underwatered christmas cactus
- Christmas cactus watering guide recap
Christmas cactus watering guide
The christmas cactus, scientific name Schlumbergera bridgessii, is a succulent plant that is native to the coastal areas of south-east Brazil. It is a member of the broader succulent plant family Schlumbergera that includes the thanksgiving cactus, holiday cactus and crab cactus (names that are sometimes mistakenly given to the christmas cactus) and the easter cactus.
Christmas cactus is a very popular houseplant in North America and gets its name due to its vibrant lilac or pink flowers that are cultivated to bloom in the US in winter (read this when your christmas cactus won’t bloom).
Unlike many other succulents, such as the desert succulent aloe that thrive in areas of scarce water and very dry air conditions, the christmas cactus grows naturally in rocks and on trees in areas of high humidity where moisture is constantly in the air.
Does Christmas cactus need humidity?
Before I cover the topic of watering your christmas cactus I must include information on humidity as this is related. Does christmas cactus need humidity?
Christmas cactus grows naturally in very humid environments and so it requires higher humidity than most other houseplants. It is therefore necessary to provide the cactus with sufficient levels of humidity to promote good health and blooms. There are a variety of ways to do this.
As I am sure you are aware high humidity levels are caused by water vapor in the air. This moisture helps christmas cactus to stay hydrated. It is therefore necessary for you to give your indoor christmas cactus plants adequate levels of humidity in their immediate environment if you want a healthy plant and vibrant blooms.
The water vapour in the air that creates the type of high humidity needed to provide moisture to a christmas cactus is almost always lacking in homes. The effect of humidity on humans makes temperatures feel higher than they actually are and this means the needed high humidity levels for growing christmas cactus feel very uncomfortable for humans.
Luckily though, there is no need to create a humid atmosphere in home, just to keep your christmas cactus happy, as it is possible to create an area of high humidity only in the localized area around your houseplant.
You do this by creating, what I call, a homemade humidity tray.
By using a tray underneath a christmas cactus plant pot, and filling it with some pebbles and a little water, it is possible to maintain the correct humidity levels around the plant. Thus you can ensure high moisture levels in the air without running the risk of overwatering the succulent (more on this later).
Simply place the cactus pot on a tray that has been filled with small pebbles and add some water to the tray. The water in tray will evaporate over time and the evaporated moisture will increase the humidity levels directly around the plant without affecting the overall room.
You will need to ensure the water in the tray is replenished as needed when it evaporates (usually every other day or every third day depending on the temperature in your home).
I also advise you to use a terracotta pot for christmas cactus because terracotta sweats moisture from the soil. This evaporation not only greatly lessens the risks of root rot (more on this later) but the evaporated moisture also helps to maintain high humidity levels around the plant. Plus, in my opinion, terracotta looks really good with succulents (read our christmas cactus soil and pot guide).
How to water christmas cactus
Although maintaining good humidity levels around your plant is important, it is crucial that you get the watering routine of a christmas cactus correct. Like all succulents, christmas cactus is very susceptible to developing some very serious problems if it is watered incorrectly.
So, below I give detailed instructions for the correct watering of christmas cactus.
Although each environment a christmas cactus houseplant will be growing in will be slightly different, as no 2 homes have exactly the same temperatures and humidity levels, the general advice given below is applicable to all areas of America because homes across the US are kept at fairly regular and consistent temperatures year-round in most states. Therefore the moisture evaporation from a christmas cactus in one state will usually be similar to one in another state.
People often ask me if they should water a christmas cactus from the top or from the bottom.
You should water christmas cactus from the bottom. Only water the plant when the top layer of soil has dried out. Sit the pot into a basin or sink filled with a few inches of water and allow the soil to soak up moisture for about 20 – 25 minutes. The watering will be complete when the top layer of soil is moist.
Most succulents do not like their foliage getting wet. As they grow is areas that get limited rainfall succulents have evolved to gather water from the environment in different ways from other plants and rarely rely on rainfall to fulfil their watering needs.
Christmas cactus leaves will get some of their water-needs meet from the high moisture content in the air – as long as you keep high humidity levels in the plant’s localized environment (see above section on humidity). And although christmas cactus leaves react well to high levels of moisture in the air they don’t like to be soaked or wetted. So, bottom watering is the preferred method for watering this succulent.
20 minutes is usually more than enough time for the soil to absorb enough water and become moist. Once removed from the basin or sink ensure excess water is allowed to drain away; the pot must have good drainage.
How much should a Christmas cactus be watered?
Now that you know how to water a christmas cactus you will no doubt be wondering how often it should be watered.
Christmas cactus should be watered when the top 2 inches of soil dries out. For most christmas cactus houseplants this will mean watering the succulent once every three weeks. Never drench the soil. The soil should be moist but never soaked.
As I will cover shortly giving a christmas cactus too much water is very dangerous for the health of the plant. Cacti have evolved to live on much less water than other types of plants and they have developed mechanisms for storing water for long periods. If you water cacti too much they will die.
Let’s take a look at the typical symptoms of overwatered christmas cactus and also briefly look at the symptoms of underwatering.
Overwatered vs underwatered christmas cactus
Although this may seem to be counterintuitive, the symptoms of an underwatered christmas cactus plant are often identical to those of an overwatered one. How can this be?
Well, when a christmas cactus is underwatered the plant will show signs of dehydration. This is pretty obvious and to be expected. However, when a christmas cactus is overwatered it will also often display the symptoms of dehydration.
Why is this?
Well, it’s because the plant is in fact dehydrated even though it has been given too much water!
You see, when plants are overwatered, and this is especially the case with succulents like christmas cactus, the excess water in the soil rots the roots of the plant. As the roots begin to rot they become incapable of absorbing moisture and thus cannot distribute that water to the rest of the plant. The plant becomes dehydrated.
Root rot is a very serious problem for any plant but because succulents should be watered much less than other houseplants they tend to suffer from overwatering much more. You see many houseplant owners will water all their plants with the same frequency and thus inadvertently overwater their succulents.
Obviously this can cause a problem when it comes to identifying whether a christmas cactus has been underwatered or overwatered. If the symptoms of underwatering and overwatering are the same (dehydration) how can you tell which is the cause for the ailing health of your christmas cactus so you can fix the problem?
Before we take a look at that let’s discuss just how long it is safe to leave a christmas cactus without water.
How long can a christmas cactus go without water?
So how long can your christmas cactus comfortably go with being watered?
A christmas cactus can go several weeks without water though as a general rule it should be watered every 3 weeks. After 6 weeks with no water a christmas cactus will start displaying signs of dehydration.
Although desert cacti can survive as long as 24 months without water not all cacti species are desert plants. The christmas cactus is not a desert succulent and requires much more watering than its desert cousins.
Christmas cactus also grows best in a humid environment where it can also get moisture from the surrounding air. If this succulent is left in high temperatures with dry air and no water it will quickly deteriorate.
How to tell if christmas cactus is overwatered or underwatered
Your initial investigation into the causes of the dehydration will need to focus on the soil.
If your plant has limp foliage and looks generally dehydrated then begin your check by by sticking your index finger down into the soil, up to the first knuckle (about 2 inches deep). If the soil is moist then there should be dirt debris on your finger when you remove it from the soil. If your finger is completely dry and free from dirt then the soil is also completely dry.
This would be a strong indication that your christmas cactus has been underwatered. Underwatering is possible even if you have been watering the plant every 3 weeks as suggested, if for instance your local environment is very warm and also lacks humidity. Dry air and very warm temperatures can quickly cause water evaporation from houseplant soil.
The obvious cure for underwatering is to water the plant. However, before you take that action I highly encourage you to look at the roots of the cactus just to be 100% sure they are not rotting.
If the soil is obviously moist, or even wet, then the plant dehydration is not due to a lack of water. Most likely it is due to too much water. Too much water leads to root rot.
Although sagging, limp foliage and stems that are mushy toward the bottom are strong indicators of overwatering and root rot, the only way to determine for sure if a christmas cactus is suffering from overwatering and root rot is to look at the roots of the plant. You will need to remove the plant from its pot to do this.
How to fix an overwatered christmas cactus
To fix an overwatered christmas cactus you must first investigate the root system.
If the roots are intact and healthy then repot the cactus into fresh soil that is only slightly moist and ensure the plant is in a location that gets daytime temperatures of about 70°F and at least 8 hours of good indirect light (see our article on christmas cactus light requirements). Use a good quality grow light if you need to give the plant an additional lighting source due to its location or the time of year when the hours of natural light are reduced.
Once the plant starts to recover you can begin a normal watering routine being careful to only water the plant when the soil dries out.
If you identify root rot or the beginnings of root rot then you must treat the plant immediately. This requires a cutting away of dead and damaged roots and repotting the plant in fresh soil.
In the article outlining how to treat aloe vera root rot I give detailed instructions for treating this problem. As aloe vera is also a succulent the advice in the aforementioned article applies equally as well to treating root rot in christmas cactus. The steps you need to take are identical. If you suspect your christmas cactus has root rot read that article and follow the advice laid down in it.
Christmas cactus watering guide recap
Below is a quick recap of the suggested routine for watering a christmas cactus houseplant.
Christmas cactus watering routine:
- Water a christmas cactus when the top 2 inches of soil dries out.
- In general, this means watering a christmas cactus houseplant every 3 weeks.
- Water the plant from the bottom.
- Sit the christmas cactus pot in a basin or sink filled with about 1″ of water.
- Leave for approximately 20 – 25 minutes or remove the pot when the top layer of soil is moist.
- Allow the excess water to drain away before replacing the plant in its permanent location.
- Never drench or soak christmas cactus soil.
Hopefully this quick christmas cactus watering guide has helped you to understand the watering needs of your succulent and also given you the information you need to avoid potential watering problems.