6. Keep tropical cacti at a steady, warm temperature. While desert cacti in their natural environment are routinely exposed to extreme temperature swings (from extremely hot during the day to extremely cold at night), tropical cacti enjoy balmy, consistently warm weather. Thus, it's a wise idea to grow tropical cacti in locations where they won't experience intense, direct sunlight during the day or chilly cold at night. Try to keep tropical cacti at a temperature of roughly 70-75o F (21-24o C) — greenhouses are great for this.