Houseplant
Christmas cactus
Schlumbergera truncata · Cactaceae
Also called: Thanksgiving cactus, Holiday cactus, Crab cactus, Zygocactus
Christmas cactus (Schlumbergera truncata) is a low-water houseplant well suited to Tucson and the low desert.
Christmas cactus at a glance
- Water use
- Low (established)
- Sun
- Bright indirect light indoors; in Tucson it must be grown as a houseplant or in deep/filtered shade on a covered patio. Direct low-desert sun scorches and reddens the segments.
- Mature size
- Typically 1-2 ft wide and 6-12 in tall, with arching, trailing flattened stem segments; spreads wider with age.
- Growth rate
- Slow to moderate; long-lived (can survive decades as a passed-down heirloom plant).
- Bloom
- Pink, red, white, salmon, orange, or purple depending on cultivar, Late fall to winter (Nov-Jan). Bloom is triggered by ~6 weeks of long (13+ hr) uninterrupted darkness and cool nights (~55-65°F) in fall.
- Cold hardiness
- Frost-tender; keep above 50°F, best 60-70°F. Bring indoors when nights drop below ~50°F (typically Nov-Mar in Tucson) and protect from any hard freeze.
- Soil
- Fast-draining, organic-rich mix (potting soil cut with perlite/bark, or a peat-based cactus/orchid blend). Slightly acidic. Always use a pot with drainage.
- Native range
- Coastal mountains of southeastern Brazil (epiphytic, growing on trees/rocks in shaded, humid forest)
- Best used as
- Indoor houseplant, Holiday gift/heirloom plant, Hanging basket, Shaded covered-patio container, Color accent
- Wildlife
- In its native range pollinated by hummingbirds; indoors it offers no significant wildlife value in Tucson.
- Toxicity
- Non-toxic to dogs, cats, and humans (per ASPCA). Safe around pets and children, though fibrous stems may cause mild stomach upset if eaten in quantity.
How to grow Christmas cactus in Tucson & the low desert
Watering
Water when the top inch of mix dries; this forest epiphyte wants more moisture than desert cacti but must drain freely. Cut back during its post-bloom and mid-summer rest. Never leave it standing in water.
Fertilizer & nutrients
Feed monthly spring through early fall with half-strength balanced houseplant fertilizer (e.g., 20-20-20) or a high-potassium bloom formula; a little extra magnesium (Epsom salt) aids blooming. Stop feeding late fall through bloom.
Pruning & care
Pinch or twist off a few stem segments after flowering to encourage branching and more blooms; the removed segments root easily as cuttings.
Notes
True S. truncata is the 'Thanksgiving cactus' (pointed, claw-like teeth on segments); the classic 'Christmas cactus' is the hybrid S. x buckleyi (rounded, scalloped segments). In Tucson grow it indoors or on a fully shaded, frost-protected covered patio. To re-bloom, give cool fall nights and long uninterrupted darkness; avoid moving it once buds set, as drafts, light changes, and over/under-watering cause bud drop. Not a sun-tolerant desert cactus.
Sources: University of Arizona Cooperative Extension; Arizona-Sonora Desert Museum; ASPCA Toxic and Non-Toxic Plant List; Missouri Botanical Garden Plant Finder