Why are my Christmas cactus buds falling off? 5 potential causes, and what to do about them

If you're a fan of festive plants but have noticed your Christmas cactus buds are falling off, it's imperative you get the need-to-know information quickly, to give your bloom the best chance of thriving throughout the festive period and beyond.

As one of the best Christmas houseplants, we all want our Christmas cacti to do well. But as the top Christmas cactus care tips will tell you, these plants are delicate, and the wrong conditions - such as changes in temperature and humidity - can cause their buds to fall off.

So if dropping buds is one of the Christmas cactus problems you've been experiencing lately, you're in the right place. We've asked the experts what causes Christmas cactus buds to fall, and what can be done about it.

Why are my Christmas cactus buds falling off?

When we asked the experts why your Christmas cactus buds might be falling off, they explained that these plants are very sensitive to changes in their environment.

'Most often, Christmas cactuses are bought from garden centres or other places where they were placed in a greenhouse with a controlled temperature, moisture levels and lighting,' says Graham Smith, gardening expert at LBS Horticulture. 'Sometimes, simply moving a cactus into your home after it has been in this climate can cause bud drop, as this is their response to a change in their environment.'

But if there's been a delay between bringing your Christmas cactus into the house and their buds falling off, there could be a number of other factors to blame.

1. Issues with watering

Knowing how often to water a Christmas cactus is key if you want to prevent buds from falling off. These plants need to be watered every two to three weeks, and an inconsistent watering schedule can lead to droppage.

'Fluctuations in moisture levels can cause plants to become stressed, which will affect bud set,' Graham explains. 'To avoid this, maintain a consistent watering schedule and allow the soil to dry out fully between waterings.'

If you've been watering your Christmas cactus more than once a fortnight, this could be causing the buds to fall off.

2. Lack of humidity

Increasing the humidity levels is a good method for perking up a Christmas cactus plant, and it turns out that lack of humidity can also be responsible for dropping buds as well.

'As they are tropical plants, Christmas cactuses thrive in 50% to 60% humidity, which is higher than the humidity of the average home,' Graham says. 'They can survive in levels slightly lower than this, but if the air is too dry this can cause bud drop.'

Use a plant mister to spritz your Christmas cactus regularly to mimic the humid environment it thrives in. 'Or, try placing the plant pot atop a shallow tray of pebbles filled with water,' Graham suggests. 'But don't allow the roots or the soil to sit in water.'

3. Temperature

Another common cause of Christmas cactus buds falling off is the wrong temperature. For optimal production of buds, the plant needs temperatures of around 18°C, which is why getting Christmas cacti to flower during winter can be tricky.

The recent drop in temperature could therefore be a likely culprit for your plant's dropping buds. 'Avoid keeping your Christmas cactus in draughty spots,' advises Kate Turner, gardening expert at Miracle-Gro. 'But equally, keep it away from radiators and other direct heat sources like an open fire.'

4. Light levels

The amount of light a Christmas cactus gets can also have a big influence on the health of its buds.

'In the run up to its flowering period, the cactus will need long periods of darkness to initiate blooming,' Graham explains. 'From September to October onwards, the plant should be placed in a room where it will receive at least 13 to 14 hours of darkness a night.'

Ideally, Christmas cacti will naturally be able to get this darkness as the days shorten over winter, but any interruptions can affect the plant. As such, moving your Christmas cactus around in a bid to find the best location can cause buds to drop, as can keeping it in direct sunlight - indirect sunlight is best.

5. Soil fertility

Lastly, if the soil fertility is off, this can also cause buds to fall. 'If the soil the Christmas cactus is in has poor fertility, this can mean that it will fail to flower,' Graham says. 'Depleted soils can lead to several deficiencies in nutrients, such as nitrogen and magnesium, which are essential to plant growth.'

Use peat-free compost and a pot with good drainage to house your plant, and it can help to add a soil fertiliser if it's really struggling. You might want to repot your Christmas cactus if you think the soil conditions aren't right.

FAQs

How can you tell if a Christmas cactus is overwatered?

Gardening expert Kate Turner says that overwatered Christmas cacti have a few telltale signs, including:

• Bud drop – if the plant's buds keep dropping, yet it’s in an optimum position, check the moisture levels.
• Soft, mushy leaves – caused by the plant starting to rot due to overwatering.
• Yellowing or shriveled stems/leaves – this can be a sign of overwatering as well as underwatering.
• Plant wilting – if the plant isn’t draining the water away, the roots suffocate, unable to take up oxygen and start to rot.

It's important to get the watering schedule just right to avoid any of these issues. You can save an overwatered plant by reducing the watering frequency immediately (Christmas cacti only need a drink every 2-3 weeks).

What does a stressed Christmas cactus look like? 

'The main signs of a stressed Christmas cactus will be wilted leaves, drooping buds and leaf discoloration,' former Royal Gardener Jack Stooks says on behalf of Spin Genie. 'This is usually due to the wrong temperature or being in direct sunlight.'

Jack explains that Christmas cacti don't like extreme temperatures, and it's best to keep it in a room where the temperature is pretty consistent.

'If the buds are falling off your Christmas cactus, the most common reason is because you would have brought it on from a regulated temperature into a cold area. Say you've bought the plant and you put it in a cold car for a while before taking it in indoors, that's going to stress the plant, so the buds will fall off over the next few days.'