Basil is the herb most people try first and the one they kill first. It is not that you have a black thumb; basil is simply fussy about a few specific things, and indoor conditions get all of them wrong by default.

Mistake 1: Not enough light Basil is a sun worshipper. It wants six to eight hours of direct light, and a typical kitchen window gives far less, especially in winter. A basil plant stretching tall with big gaps between leaves is screaming for more light. Move it to your brightest window or add an inexpensive LED grow light a few inches above it.

Mistake 2: Overwatering The grocery-store basil you bought was grown in a tiny plug crammed with too many seedlings, sitting in constantly wet peat. Indoors that combination rots roots fast. Water only when the top inch of soil feels dry, then water thoroughly until it drains out the bottom.

Mistake 3: Leaving it in the original pot That supermarket pot holds a dozen plants fighting for the same root space. Within days they exhaust it. Split the clump into two or three pots, or transplant into one larger container with fresh potting mix.

Mistake 4: Never pinching it Basil left alone bolts to flower and turns bitter. Pinch off the top set of leaves every week or two, just above a lower leaf pair. This forces side branches and keeps the plant bushy, productive, and sweet for months instead of weeks.