Yes. Drainage is of vital importance to ensure your plant’s best possible health. Using a planter without a drainage hole may cause water to pool at the bottom – when this happens, your plant is unable to absorb oxygen or nutrients. Without being able to “breathe,” your plant will suffocate. The excess water will also cause the growth of fungus, also known as root rot.
If your planter does not have a hole at the bottom, you can drill one in. Another tip is to use a plastic planter with a drainage hole inside a larger planter without a drainage hole.