A white Christmas cactus (usually a variety of Schlumbergera) isn’t built for harsh summer conditions, so the goal is to protect it from heat stress while keeping it gently growing. Here’s how to handle it:

☀️ Light (this is critical)
Keep it in bright, indirect light. Direct summer sun can scorch the leaves, especially midday. A spot near a window with sheer curtains or shaded balcony works well.

💧 Watering
Water when the top 2–3 cm of soil feels dry. In summer, that usually means a bit more frequent watering, but never let it sit in soggy soil—root rot is its biggest enemy.

🌡️ Temperature & humidity
It prefers 18–26°C. If you’re in a hot climate, keep it away from heat sources and give it good airflow. It loves humidity, so mist lightly or place a tray of water nearby.

🌱 Soil & drainage
Use a well-draining mix (cactus mix + perlite works great). Make sure the pot has drainage holes—this plant hates “wet feet.”

🌿 Feeding
During summer (its active growth phase), feed lightly every 3–4 weeks with a balanced liquid fertilizer at half strength.

✂️ Pruning (optional)
You can pinch off a few segments to encourage bushier growth—but don’t overdo it in extreme heat.

⚠️ What to avoid

  • Harsh direct sun
  • Overwatering
  • Sudden temperature swings (like strong AC blasts)

If you keep it comfortable through summer, it’ll reward you later with blooms around the holiday season. If you want, I can also show you how to trigger blooming when fall comes.