When to Water Agave and Cacti
The time of day you water makes a huge difference in the desert, especially for agave and cacti.
To minimize water losses and have optimal irrigation efficiency, I water my greenhouses at night. Especially during a summer day, watering in the heat can cause your plant to undergo heat stress, which can damage your plants significantly.
Why Water at Night?
High daytime heat (often above 90°F) drives rapid evaporation, so daytime irrigation rarely reaches the plants’ tissues.
CAM physiology: Agave and cactus open their stomata only at night (Crassulacean Acid Metabolism), absorbing CO₂ and water under cooler, more humid conditions and closing during the day to conserve moisture.
Seedling Considerations
Young agave and cactus seedlings rely almost entirely on nocturnal absorption through their stomata because their root systems are still developing. Night watering ensures maximum uptake without runoff.
Once plants mature and establish deeper roots, you can switch to watering in the cool morning or early evening—always avoiding peak sun.
Temperature-Driven Transpiration
A nighttime temperature drop (for example, from 90°F to 50–60°F) creates a 30–40° differential that drives water movement and transpiration, letting these succulents thrive on minimal irrigation.
Key Takeaway
For any agave or cactus nursery—especially when raising young plants—nighttime watering aligns with their natural CAM cycle, minimizes evaporation, and maximizes water use efficiency.
Enjoyed this explanation? Watch the original video below to see the full demonstration: