The Christmas cactus is a fascinating succulent that blooms right in time with its holiday namesake (at least, ideally). Their Thanksgiving and Easter cacti relatives do the same. Christmas cactus (Schlumbergera x buckleyi) usually begins blooming in December and carries on through January. Its billowy, tubular blooms put on a show in red, white, pink, purple, coral, and bicolor shades.
Christmas cactus is an adaptable houseplant and has to be since mirroring its natural environment is a challenge. They originate in Brazilian rainforests, hanging out with orchids as epiphytes on the nooks of tree branches and crannies of rock crevices. They come to our homes from commercial greenhouses optimized for their successful growth – another challenge to mimic at home.
So, expect a little bud drop as the plants move between conditions, from the nursery to the home, a summer outdoors back inside, or to different display spots. They’ll likely lose a few buds as they acclimate to fluctuations in their growing environment.
If your cactus is losing a lot of buds, and to prevent buds from dropping in the first place, we’ll explore the primary reasons. Cultural conditions, especially temperature changes, lighting, or water issues, are often the culprit. With a few adjustments, your Christmas cactus can return to its happy, blooming glory.
Avoid Temperature Sweeps
Drastic temperature fluctuations are common as we move plants this time of year, but the resulting stress is a leading cause of bud drop. The cacti benefit from cool nighttime temperatures to initiate flowering, but quick extremes halt budding.
In their mountain forests at elevations of 3000 to 5000 feet, ideal daytime temperatures are between 70-80°F (21-27°C). Nighttime temperatures are around 55-60°F (13-16°C) in winter. Warm nighttime temperatures – 70°F (21°C) or higher – or extended periods beyond mid-September limit bud development or cause young buds to fall. Place pots in a cool room or near a window for lower temperatures.
To avoid sudden chill or heat and decreasing humidity, keep them away from drafts. Heating and air vents, open windows, space heaters, and fireplaces cause sweeping fluctuations that may inhibit budding. The movement of fresh, cool air is beneficial, but cold blasts or drying heat are hindrances.
Offer the Best Light to Initiate Budding
These tropicals require plenty of bright, indirect light to flourish. Near a bright window is a good situation. Insufficient light doesn’t support the energy needed to flower. Too much direct sunshine, especially afternoon rays, can scorch stems and buds and prevent them from holding.
Christmas cactus responds to shorter day lengths (and longer nighttime darkness) to develop strong buds. Along with cool nighttime temperatures from September on, they need 12 hours of darkness for the best budding.
Turn off the lights in the evening in the growing room. Some gardeners place a light-blocking cover over the specimen at night for several weeks to provide necessary hours of darkness and prompt a holiday bloom time.
Balance Water Needs
Water fluctuations are a top cause of losing viable buds. In nature, the epiphytes absorb plenty of rain and moisture from the air, and their roots don’t sit for prolonged periods in wet soils. Christmas cacti are true cacti, but not as xeric as desert-dwelling types. They benefit moisture in moderation.
Water thoroughly when potting media feels dry one inch below the surface. Frequency is usually once a week or two, depending on the growing environment. Err on the dry side rather than overwatering, but don’t allow soil to dry out completely. Well-draining potting mix is best; it may warrant watering more regularly than those that hold moisture.
Overwatering damages roots and leads to their inability to uptake water and nutrients necessary for flowering. Underwatering causes the plant to enter preservation mode, directing any moisture to roots and foliage rather than supporting buds. The stress can cause bud drop.
Some growers recommend lessening water sessions slightly from August to September as buds begin to form. The reduction prompts strong stems and bud initiation. Resume regular sessions as the buds swell (and don’t allow soils to dry out).
Hold Off on Fertilizing
In the wild, the cacti receive nitrogen through raindrops and other nutrients from decaying plant material on trees. Houseplants get a boost from balanced, low-grade, diluted formulas. An overload of nitrogen, though, promotes foliar growth but inhibits bud development, resulting in less flowering. Stop fertilizing Christmas cactus in September or October to promote budding and strong stems.
Pick up fertilizing again in early spring. Opt for an organic houseplant fertilizer (like 10-10-10) and use it at ¼ strength. Apply it every other watering session in the warmer months or once a month if using full-strength applications.
Assess Potting Needs
The easy-care growers seldom need repotting. They prefer tight quarters and need slightly crowded roots to produce blooms. They can live for years in a single container. The threshold to repot comes from indicators of reduced vigor like halted new growth, lack of budding, bud drop, and withered young stems. You may also see roots protruding from drainage holes or popping up on the surface. Stems may wilt, and soil will dry out quickly.
After inventorying moisture, light, and temperature conditions, assessing living quarters is a good next step. A main reason to repot houseplants is to refresh soil nutrition. Potting mixes break down with regular water and root development. They lack nutrients and aeration with reduced oxygenation necessary for health.
The best time to repot Christmas cactus is right after flowering. Transplanting at other times can affect foliar growth and budding. The process may entail fresh soil and root pruning or moving to a slightly larger container.
Scout for Pests and Diseases
Fortunately, the epiphytes have few pest and disease problems. Scale, mealybugs, and spider mites may be visitors. Root rot from overwatering can occur.
Insects
Scale are common pests that pierce leaves and stems to feed on sap. You may notice a sticky residue. The little legless blobs usually appear on the undersides of leaves and stems as black, gray, or silvery dots. Leaves may yellow and drop, with stems dying back in heavy infestations. Remove affected leaves (and branches, if severe).
Mealybugs are soft-bodied and look like tiny tufts of white cotton on leaves and stems. Infestations are visible by the insects themselves and by yellowing, wilting, or stunted leaves.
Spider mites are common in houseplants and live on the undersides of leaves, indicated by webbing and light yellowing of leaf surfaces. Outdoors, beneficial predatory insects like ladybugs and predatory mites help control populations.
Scale, mealybugs, and spider mites gravitate toward specimens stressed by under or overwatering. For small populations, run plants under a stream of water to displace the pests. Dab them with a Q-tip or cotton swap soaked in isopropyl alcohol. Insecticidal soaps and horticultural oils are effective as more potent treatments.
Root Rot
A common fungal disease to look out for is root rot. Overwatering creates saturated conditions that promote development. Rot causes the roots to turn brown and mushy; as they decay, they can’t function to support growth.
Plants in overly soggy media with poor airflow may show yellowing and wilting leaves. Check the roots and clip off those that are brown or damaged.
Replant the cacti in fresh media and water thoroughly. Continue with a watering regimen that prevents prolonged oversaturation. If caught early, you may see rebounding growth. Since Christmas cacti propagate easily from stem cuttings, it may be wise to take a few in case the roots can’t recover.
