(7 Reasons) Why your Christmas Cactus Isn’t Blooming

So Christmas has rolled around, and your aptly named Christmas Cactus isn’t blooming? What Gives?

I had the same problem. My Christmas cactus buds either fell off or did not emerge. So I did some research and consulted some experts at work (I work in a garden center) who taught me all the tips, secrets, and techniques to get a Christmas cactus blooming.

It turns out that Christmas cacti need a very specific set of conditions to bloom. From my first-hand experience, I take you through all the tips that helped me identify why my Christmas catus wasn’t blooming and the techniques to ensure it blooms in time for Christmas in a step-by-step guide…

If you only have 2 minutes, here is a quick explanation…

The Christmas cactus does not bloom because of drought stress or too many hours of light, as it is a short-day plant. Christmas cacti are adapted to rainforests with high humidity and rainfall. They do not flower if they are dry or if there are too many hours of light during flower formation.

FYI there are Christmas cacti and Easter cacti which are both very similar and flower during the corresponding holidays so, if your CHRISTMAS cactus is not flowering I would check the label to ensure it is not an EASTER cactus!! I’ve seen a lot of people get caught up in this one!

Several other factors can prevent Christmas cactus (Schlumbergera) flowering, which I have summarized here:

Keep reading to learn why your Christmas cactus is not flowering, the best practices, and how to implement solutions so that it can display flowers.

1. Under Watering and Low Humidity

So I was taught that in order to make your Christmas cacti to flower you have to simulate some of te conditions of its native environment…

Christmas cactus is a plant that is native to the tropical rainforests of Brazil where it grows in hot and humid conditions with relatively high rainfall, and whilst shaded by the canopy of trees.

This is, of course, in stark contrast to how we think of most cacti species, which grow in hot sandy deserts with low humidity and infrequent rainfall and have several adaptations to cope with drought.

When people hear the word ‘cactus’ when referring to the Christmas cactus, the associations with the desert-dwelling species cause people to assume that the Christmas cactus does not need much watering when the opposite is true.

What I’ve seen first hand is that drought stress prevents Christmas Cactus from flowering. If the cactus is underwatered, the soil dries out too quickly and the humidity is too low Christmas cactus does not flower due to drought stress.

This is a mistake that I personally made and my cactus did not flower properly until I recreated some of the conditions of the cactus native environment with higher levels of humidity and watering more often.

To encourage a Christmas cactus to bloom, I followed these steps…

• Water your Christmas cactus more often. I did some experimentation and found that, for me, watering once per week provided my cactus with the optimal balance of moisture to meet the water requirements without causing root rot so that the cactus could bloom without any undue moisture stress. The advice I had was to wait until the top inch of soil feels dry before watering, which, for me, took a week, but I recommend that you test this yourself to establish how long it takes for the top inch of soil to dry out on your plant as there are some variables (such as climate) that are specific to you and your Christmas cactus.
• Spray the cactus with mist regularly, particularly if you live in an arid climate. Houses tend to be lower in humidity anyway compared to outdoors and much lower than rainforests, so I was advised that misting is essential to create a humid micro-climate to slow water loss from the leaves and recreate the plant’s ideal conditions. For best results, I spray the leaves at least once a week in temperate climates and 2 or 3 times a week in dry climates.
• Water the cactus with a generous soak. Watering too lightly causes the water to not infiltrate the soil properly, and the moisture does not reach the roots, causing drought stress, which prevents flowering.

Another potential problem when it comes to underwatering is if the cactus is planted in potting soil that contains peat as peat repels water off the surface when it dries out.

I saw this first hand when my friends Christmas cacti appeared to be suffered from underwatering despite waterng once per week. I learned that when peat dries out it can repel water off its surface. This can prevent water from infiltrating the soil properly and the roots are not able to uptake the moisture they require.

So the solution that I tested for this was to submerge the soil in a basin of water for 10 minutes to ensure that water can absorb properly to reach the roots.

This of course worked for a short time but eventually I replant the cactus in more porous soil amended with horticultural sand or grit which allows water to reach the roots much better to avoid the problem of dry soil.

With regular watering and higher levels of localized humidity due to spraying mist on the leaves to emulate the natural environment, the Christmas cactus has a better chance of blooming in your home.

(Read my article to learn how often and how much to water your Christmas cactus according to your climate and conditions).

2. Christmas Cactus Requires at least 12 Hours of Darkness to Flower

Okay, so this is the sort of thing that, if you weren’t taught this, it is unlikely that you would discover it on your own! I’ve learned that Christmas cactus is rather unusual in that it is a ‘short day plant‘ which means requires at least 12 hours or more of unbroken darkness to form flower buds.

If the 12 hours or more darkness is interrupted by turning on lights in the middle of the night then this can interfere with the development of the cacti flower buds and prevent it from flowering.

So if your Christmas cactus is in your kitchen and you pop in there for a midnight snack, then the light that is on even for a moment can disrupt the period of darkness to the extent that the Christmas cactus does not flower!

This is due to the Christmas cactus being adapted to sense seasonal change by detecting changes in daylight hours to initiate flower bud formation.

Most plants detect a seasonal temperature change, which then promotes the formation of flower buds, whereas Christmas Cactus relies on both day length and temperature change in its native rainforest environment to stimulate the formation of flower buds and signal the right time for flowering.

To promote blooms at around Christmas time ensure that your cactus is in a room that stays dark at night as even turning a bright light on for a few minutes can interfere with the development of flowering.

One potential solution is to place a light-exuding cloth over the top of your Christmas cactus to ensure that it has a long enough period of darkness to promote flowering. Which is exactly what I do to keep it dark.

Avoid this common mistake: Do not put your Christmas cactus in a cupboard overnight (which was my first instinct!) as Christmas cacti are fussy about being moved a lot! Every time you move them they have to get used to a new set of conditions which, from experience, can also interfere with bud development and flowering.

(Read my article for more, if your flower buds are forming and then drop off, why are my Christmas cactus buds dropping?)

3. Prefers Being Pot Bound for Flowering

So when I spoke to my colleagues at the garden center they taught me Christmas cactus actually has a preference for smaller pots with their roots being somewhat restricted and pot-bound.

The reason I discovered this is Christmas cacti don’t necessarily flower if they are not under some kind of stress.

If your Christmas cactus is planted in a large pot then their energy tend to be redirected into growing out the roots system rather then into flowering.

I have noticed this effect happen with some of my garden plants too, with roses tending to flower better after 2 or 3 years after planting.

When the Cactus is pot-bound, it prioritizes producing flower buds over the growth and development of the plant, as flowering is the plant’s way to reproduce as a strategy to survive even in hostile environments. Which, if you ask me, is a shrewd survival strategy.

If the plant is perfectly content with its conditions, then there is less incentive to produce flowers as there is less of an urgent threat to its survival.

So to get your Christmas cactus flowering, I recommend Planting your Christmas cactus in a pot just larger than the root ball (rather than a large pot with excessive capacity) to help promote blooming.

I personally leave it 3 or 4 years between repotting and my Christmas cactus flowers very well. Even when I do repot it, I do so in a pot that is only around 1 size up from the last pot to further incentivise flowering.

4. Too Hot or Too Cold Can Prevent Christmas Cactus from Flowering

From my research, I ascertained that the optimal growing temperature for Christmas cactus is around an average room temperature of 68°F (20°C) but it can tolerate a wide range of temperatures due to its adaptability to fluctuating conditions in its mountainous rainforest environment.

In the Northern Hemisphere, Christmas cactus starts to develop its flower buds in September.

Important tip: The flower buds then develop for 6 weeks with an evening temperature slightly on the cooler side of approximately 60°F (15°C), but once the flowers have emerged, they tend to last longer with a more consistent temperature of 68°F (20°C).

Remember we talked about simulating the conditions of the plant’s native environment? This sequence of temperatures replicates the same cycle for bud formation in the Christmas cactus’s native environment.

Whilst these temperature ranges are best practices for promoting flowers, I have personally seen an excellent display of flowers year after year when my plant is placed on a kitchen window sill, which receives indirect bright light, slightly cooler temperatures, and higher levels of humidity than other areas of the house without necessarily following a strict pattern of temperature change.

However, if your cactus is not flowering, then keeping it nice and cool during bud formation is going to give it the best chance of flowering.

I think the most common mistake that catches people out is that their plant is on a window sill above a radiator. The radiator increases the heat in the room at night, which is in contrast to how the Cactus grows in the wild, where it experiences cooler temperatures at night.

So find a nice unheated spot for your cactus, such as a window sill away from a radiator.

5. Overwatering Prevents Blooming

As we discussed, our Christmas cactus thrives and flowers best with an optimal balance of watering.

Christmas cactus is an epiphytic plant (grows on trees) that attains water from the air or moist areas of the tree or plant where it grows.

Therefore Christmas cactus has a preference for porous, aerated soil that holds some moisture yet allows water to drain quickly.

If you water Christmas cactus too often or plant it in relatively compact soil, then this can exclude air from around the roots which can prevent effective root respiration and cause root rot which causes the cactus to droop or wilt and turn yellow.

(There can be several reasons why Christmas cactus wilts other than overwatering, read my article why is my Christmas cactus wilting for the solutions).

When the cactus is in overly damp soil, it does not flower.

Other causes of too much moisture around the roots are:

• Potting soil that has not been amended with sand grit or perlite. We need to amend the soil to increase the drainage.
• The use of saucers, trays, and decorative outer pots. Empty any saucers, trays, or pots regularly that are used to prevent excess water from spilling in your home. This prevents watering pooling around the roots which keeps the soil too damp and causes root rot.

As I work in a garden center I am able to observe what potting soil commercial growers use for potting up Christmas cacti. I even had some direct correspondence with them asking their opinion for the best potting soil to ensure that the plant flowers.

Pro Tip: They told me that you should ideally, plant the cactus in soil that is 3 parts potting soil and 1 part grit or perlite to maintain porous soil structure.

They told me that the large particle size of grit and perlite allows air in the potting medium to allow water to drain efficiently and to prevent root rot.

However, they emphasized that good soil has to be in conjunction with the right watering practices. Therefore, we need to water our Christmas Cactus once a week with a generous soak and mist the leaves but allow the surface of the soil to dry to the touch to allow for an exchange of gas for root respiration.

This helps to achieve the preferred balance of moisture for your cactus so that it can flower rather than suffer moisture stress or root rot.

6. Too Much Sun Impacts Flowering

Whilst most cacti prefer full sun, Christmas cactus is a plant that has adapted to growing in bright, indirect light under a tree canopy.

I have observed that if the cactus is located in an area of sun, the leaves turn purple or red as they try to prevent sunburn.

Full sun is contrary to the conditions to which it is adapted, and the stress of too much sun prevents flowering and can cause drought due to drying out the pot too quickly and lowering humidity.

Therefore what we need to do is to place our cactus in an area of bright indirect light (rather than shade) to give the plant enough energy to flower but not to suffer sunburn or drought stress.

7. Too Much Fertilizer In Fall Prevents Flowering

So the advice from professional growers is that Christmas cacti are not necessarily heavy feeders and do not necessarily require fertilizer for flowering.

If you have been applying fertilizer during the period of bud formation from September, then this is likely to prevent flowering, and the plant can grow droopy.

However, according to research a half strength liquid ordinary house plant fertilizer applied once per month during Spring and Summer can prevent any nutrient deficiency that can reduce flowering.

It is worth emphasizing that you should always apply at half-strength only feed once per month and avoid fertilizing from late Summer for optimal bud formation and more flowers.

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

I’d love to see pictures of your Christmas cacti and hear your perspective. What has or hasn’t worked for you? Do you have any questions?? Let me know in the comments below!!

Key Takeaways:

• Christmas cacti don’t flower if they suffer from drought stress due to underwatering, low humidity, and too many hours of light during flower bud formation. It requires frequent watering and regular misting and at least 12 hours of darkness for 6 weeks before flowering.
• The Christmas cactus prefers cooler temperatures of around 60°F (15°C) from September while the flower buds are forming to emulate the natural conditions in its native habit. For optimal growing conditions, the Christmas cactus prefers temperatures around 68°F (20°C).
• Overwatering can cause cactus stress and root rot, which prevents flowering.
• Too much sun can burn the plant and dry it out quickly, causing drought stress, which can also prevent flowering.