Which of the following is a crucial step in watering container plants?

Ensuring that water drains out of the bottom of the container is crucial for healthy plant growth. This practice helps prevent water from pooling at the bottom, which can lead to overwatering and root rot. When water drains out properly, it ensures that the plant's roots are receiving adequate moisture while also allowing for aeration of the soil, which is essential for root health.

This drainage process ensures that excess water can escape, and it helps maintain the right moisture level in the soil. Without this drainage, the soil can become waterlogged, creating an unhealthy environment for the roots. Container plants, in particular, are susceptible to problems associated with water retention, making this step critical in their care.