Minecraft wiki entry for Zero-ticking, associated text: The farms worked by exploiting certain buggy behavior. When the block supporting a plant is instantly replaced with another of the same block, the plant forcibly receives a random tick. Chorus Plants require only a single random tick to grow, plants like Cactus and Sugar Cane require 16 random ticks to grow, and still other plants react differently to random ticks. In essence, the exploit allows the plants to grow and be farmed at very high speeds for relatively low build cost.