Why is My Christmas Cactus Dropping Buds?

Why is my Christmas cactus dropping buds

Have you ever got all excited about your Christmas cactus flower, only for the buds to all drop off? Same here! This happened to me when I first started growing my Christmas cacti. However, since I now work in a garden center and studied botany, I have been privileged enough to talk to some expert growers and the taught me all the secrets and techniques to prevent the buds fall off…

I discovered that the reason my Christmas cactus’s buds were falling off was because I was unintentionally exposing my cactus to too much artificial light…

Christmas cactus drop flower buds because of drought stress, fluctuating temperatures, or due to artificial light interrupting the 12 hours of darkness required for the development of flower buds.

I learned that Christmas cacti are ‘short day’ plants, which means they require more consecutive hours of darkness than light to form flower buds.

To establish why the buds fall from Christmas cacti, I think it is important that we know the optimal conditions for bud formation.

This is because the cause of bud drop is usually due to a sudden change in conditions or a significant deviation from the optimal growing environment.

The Optimal Conditions for Christmas Cactus Flower Bud Formation

The flower buds of Christmas cactus form most often in September.

The following conditions are required to ensure your flower buds develop properly:

  • 12 or more hours of uninterrupted darkness from September onward every evening for at least 6 weeks. Christmas cacti are short-day plants that require more hours of darkness than light during bud formation. This is due to adaptations to detect a seasonal change in its environment, which stimulates flowering.
  • Cooler temperatures during bud formation than usual. The optimal temperature for bud formation is around 60°F (15°C) during the 12 or more hours of darkness. This temperature change emulates the cooler seasonal temperatures at this time of year in its native Brazilian environment.
  • Bright indirect light during the day gives the Christmas cactus the energy required for bud formation. Too much shade can contribute to flower buds falling off.
  • Watering around once per week so that the surface of the soil is dry to the touch between bouts of watering is the optimal balance of moisture, for Christmas cactus during bud formation. Mist the plant once or twice per week and keep it out of any significant air currents.
  • Do not apply any fertilizer from late Summer when the flower buds are forming. Additional fertilizer can stimulate foliage growth rather than the formation of buds.
  • A consistent environment without moving the plant or turning it around. Christmas cacti get very accustomed to their surroundings and do not like to be moved when the buds are developing.

If your Christmas cactus experiences conditions contrary to this, then this is the likely cause of flowers not forming or dropping off.

Keep reading to learn why your buds are falling off before they can display flowers…

(I have listed the causes of bud drop in order of which is most common).

Underwatering and Low Humidity Causes Buds to Drop off

As our Christmas cacti are native to the mountainous rainforests in Brazil, they thrive in high humidity and frequent rainfall.

This is in stark contrast to other desert-dwelling species of cactus that we know and love, which thrive in hot and dry conditions with little rainfall.

If the humidity is too low in your home, the flower buds drop off Christmas cactus during their formation. (This has happened to me before!)

Houses tend to have low humidity anyway, but I have noticed that some things can exacerbate the lack of humidity and increase the risk of bud drop, such as:

  • Air currents from air conditioning.
  • Fluctuating heat and airflow from forced air.
  • Draughty areas of the house.
  • Convection currents are caused by sources of heat during Winter.

My solution to this is to try to locate your Cactus in a relatively still area of the house (although moving the plant during bud formation is not advised).

To counteract these causes of low humidity and to mimic the conditions of the cactus rainforest habitat, I used to spray mist on the leaves two or three times a week, but now I have a humidifier because I have so many topical plants in need of humidity! From experience, the misting worked well for retaining my Christmas cactus’s buds, but the humidifier is a lot more convenient.

This helps to reduce water loss (transpiration) from the leaves to mitigate drought stress and creates more favorable conditions for the Christmas cactus to develop its flowers.


I think because people associate cacti with drought tolerance and desert conditions, the topical Christmas cactus is often underwater, which causes drought stress and harms the formation of flower buds.

From my conversation with a houseplant specialist at my garden center, they taught me that the correct balance of watering is critical to avoid flower buds dropping.

Typically, I water around once per week so that the soil is evenly moist but the surface is dry to the touch between bouts of watering, meets the moisture requirements of the cactus, and avoids any problems with overwatering or underwatering.

However, there are many variables to watering, so I recommend that you read my article on how often and how much to water Christmas cactus and for all the best watering practices.

Interrupted Darkness Interferes with the Formation of Flowers

Christmas cactus displaying its numerous flowers.
This is my Christmas cactus displaying its numerous flowers after I learned they should be in uninterrupted darkness.

I had to do a lot of research for this bit! Christmas cacti are relatively unusual in that they are ‘short day‘ plants, which means they rely on shortening day length to stimulate the formation of flowers.

There must be more hours of darkness (more then 12 hours) then light for your Christmas cactus to form flowers properly.

If you turn on a bright light in the middle of the night, even for a short time, this interrupts the plant’s period of darkness and can either cause the plant to not display flowers or the developing buds to fall off exactly the reason my Christmas cactus kept dropping its buds! At first, it was so mystifying!

If it is difficult to find a room in your home that is typically dark without any artificial light for more than 12 hours (as I did) then I recommend using a light excluding cloth over your Christmas cactus for the 6 weeks or so whilst the buds are developing.

You can also use a cardboard box over your plant, as long as you remember to take it off after the 14 or so hours!

I personally use a thick table cloth, which works perfectly well. As you can see in the photo above, my Christmas cactus is now flowering abundantly, to my heart’s joy!!

(If your Cactus does not display any flowers at all, then read my article Why is my Christmas cactus not blooming for the solutions).

Moving the Christmas Cactus can Cause Flower buds to drop off

When I first heard the 12 hours of darkness rule for Christmas cacti, my first instinct was to move my plant not into a cupboard underneath the stairs in my house, but I’m glad I didn’t!

A common mistake that results in bud drop is relocating the cactus whilst the flowers are developing.

I’ve learned that Christmas cactus requires quite a specific sequence of conditions for flowering, so moving the plant can disrupt the environment to which the plant is familiar which causes flower bud drop.

Interestingly enough, a change in airflow is often a culprit of bud drop, as is a difference in the direction of the light source. I think we need to just consider how specific that is for a moment, it can be the difference in light direction!

When preparing Christmas cacti for sale, the growers make sure that the Christmas cactus has one solid, consistent direction of light so that it can develop its buds and flower when on display for sale.

I turn a lot of my houseplant around 90 degrees every time I water to ensure even growth, but do not do this for your Christmas cactus.

Turning the plant around or moving it to a different window sill changes the direction of light. What I’ve observed is that the flower buds often grow toward the new source of the brightest light and then drop off as a response.

Ensure that your cactus stays in one consistent place during the flower bud formation from around September and try not to move it or turn it around for any reason to reduce stress and prevent the buds from dropping.

Saturated Soil Causes Flower Buds to Drop

Whilst Christmas cacti are rainforest plants they are epiphytic which means they grow on other trees branches and off the ground, which means they do not tolerate their roots being in Damp or boggy soil.

The secret is to keep the soil evenly moist but well-draining.

Too much moisture around the roots can cause root rot, an overall drooping appearance, and flower buds to drop.

Several factors cause damp soil and result in buds falling off:

  • Overwatering. Typically, watering once per week is enough during bud formation.
  • Pots without drainage holes in the base. Christmas cactus does not tolerate its roots in standing water. Ensure that your pot has drainage holes in the base and that they do not become blocked with compacted soil or roots.
  • The use of saucers, trays, and decorative outer pots. Excess water should be able to escape freely from the bottom of the pot. If the saucer, tray, or outer pot pools water then the soil can stay too damp and the flower buds fall off due to stress.

Ensure that your potted Christmas cactus plants have good drainage to maintain the optimal balance of moisture during bud formation and avoid the flower buds falling off.

Decorative outer pots can prevent water from draining properly .
Here is my friend’s Christmas cacti; they asked me to diagnose why the buds were falling off. I lifted the plastic pot out of its Decorative outer pot and discovered it was sat in a pool of water, which was of course the main problem!…

(If your Christmas cactus is excessively drooping or wilting read my article why is my Christmas cactus wilting for the solution).

Fluctuating Temperatures

I’ve found that Christmas cacti are fairly adaptable when growing g vegetatively outside of flowering. Mine is in the kitchen and often gets a range oof temperatures but fluctuating temperatures whilst the flower buds are forming often causes them to drop off.

As we’ve discussed, Christmas Cactus are native to mountainous Brazilian rainforest regions and they are accustomed to cooler temperatures and shorter days whilst the flower buds develop.

My Best Tip: The advice I received from expert growers is to try to keep the temperature at around 60°F (15°C) from September for around 6 weeks in order for buds to develop. Any temperatures that are considerably different from this can cause the flower buds to drop.

Once the flowers have emerged, a temperature of 68°F (20°C) is thought to prolong the flowering time.

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

Key Takeaways:

  • The reasons for the Christmas cactus dropping its flower buds are drought stress, fluctuating temperatures, overwatering, and too much artificial light at night.
  • Christmas cacti require evenly moist soil, higher humidity, and more hours of darkness than light for 6 weeks from September to form buds.
  • If you relocate the cactus during flower bud formation and change the direction of the brightest light, then the flower buds often try to turn towards more light and then drop off as a sign of stress.
  • Keep Christmas cactus at lower temperatures during bud formation and spray the leaves to increase humidity.

Leave a Reply

Your email address will not be published. Required fields are marked *

Recent Posts