For most people, rosemary is considered the hardest herb to grow indoors. It needs very bright light, good airflow, and well-draining conditions, which are difficult to maintain consistently inside a home.

Rosemary naturally grows as a woody, sun-loving plant outdoors. Indoors, it often struggles with low light and excess moisture, leading to weak growth or root problems. Unlike softer herbs, it does not recover quickly from mistakes and grows slowly when conditions are not ideal.

Herbs become hardest to grow indoors when their natural growth habits do not match indoor limits. Plants that prefer strong sun, dry air, and plenty of space tend to perform poorly without special care.

In real indoor setups, beginners usually find rosemary challenging compared to more forgiving herbs like mint, basil, or parsley.