According to a study, manipulating light exposure and temperature can significantly influence flowering in Schlumbergera species.1
By implementing these seven expert-approved September hacks, you’ll be well on your way to a Christmas cactus bursting with blooms.
1. Dial Back the Watering
One of the key triggers for bud development in Christmas cacti is a dormancy period initiated by drier conditions. In September, start allowing the soil to dry out slightly between waterings.
This doesn’t mean letting the plant completely dry out, but wait until the top inch of soil feels dry to the touch before giving it a drink.
Overwatering is one of the most common reasons Christmas cacti fail to bloom. Too much moisture can lead to root rot and prevent the plant from entering the dormancy it needs to set buds.
2. Give It the Dark Treatment
Christmas cacti need 12-14 hours of complete darkness each night for about 6-8 weeks to form buds.
Starting in September, place your cactus in a dark room at night or cover it overnight with a box or bag. Be sure to provide bright, indirect light during the day, as the plant still needs this to thrive.
Even brief exposure to light at night can interrupt this process, so be diligent about providing long stretches of uninterrupted darkness. Set a reminder on your phone to help you keep the dark treatment on track until you see tiny buds begin to develop.
3. Keep Things Cool
Temperature is another important factor in getting Christmas cacti to bloom. They prefer cooler temperatures between 50-55°F at night during bud formation.
If your home tends to be warm in the fall, try placing the plant in a cooler room or near a drafty window. Avoid placing your Christmas cactus near heat sources like radiators, fireplaces, or heating vents, which can cause buds to drop.
Sudden temperature fluctuations can also stress the plant and inhibit flowering, so aim for consistent cool nights.
4. Pause the Fertilizer
While Christmas cacti benefit from regular fertilizing during the growing season, it’s best to hold off on feeding in the fall as you’re trying to encourage blooming. Excess nutrients at this stage can hinder bud development.
Wait to resume fertilizing until the plant begins actively growing again in late winter or early spring.
At that point, you can apply a balanced, water-soluble fertilizer at half strength every 2-4 weeks to support healthy growth.
5. Prune for More Blooms
Pruning your Christmas cactus in early September can encourage fuller, more abundant blooming.
Using clean, sharp scissors or pruning shears, trim back the stem segments, leaving at least three segments on each branch. The pruned pieces can be rooted in a moist potting mix to propagate new plants.
Pruning helps maintain an attractive, compact shape and stimulates branching, which leads to more flowers.
New flower buds will develop at the end of each stem, so more stems mean more potential for a spectacular floral display.
6. Boost the Humidity
As tropical rainforest natives, Christmas cacti appreciate extra humidity, especially during bud development.
If your home’s air is dry, consider running a humidifier near the plant or placing it on a pebble tray filled with water. Just be sure the pot isn’t sitting directly in the water.
Grouping your Christmas cactus with other humidity-loving plants can also help create a more hospitable microclimate.
Misting the plant occasionally with room-temperature water can also provide a humidity boost.
7. Ensure Proper Potting
A Christmas cactus cramped in its container is more likely to direct its energy toward flowering rather than growth. Keep your cactus slightly pot-bound, only moving it to a pot one size larger every 2-3 years as needed.
Make sure the pot has good drainage to prevent soggy soil. A well-draining potting mix is essential for Christmas cactus health and blooming.
Use a mix formulated for succulents and cacti, or create your blend with one part potting soil, two parts peat moss, and one part sand or perlite.
With proper care and patience, your efforts will be rewarded with a spectacular display of vibrant blooms just in time for the holidays.
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Nancy has been a plant person from an early age. That interest blossomed into a bachelor’s in biology from Elmira College and a master’s degree in horticulture and communications from the University of Kentucky. Nancy worked in plant taxonomy at the University of Florida and the L. H. Bailey Hortorium at Cornell University, and wrote and edited gardening books at Rodale Press in Emmaus, PA. Her interests are plant identification, gardening, hiking, and reading.