What brown tips actually mean
Spoiler: it's usually not overwatering. Here's how to actually read the signs.
Brown tips on houseplants cause a disproportionate amount of anxiety. They shouldn't. Brown tips are information — usually useful information, if you know what to look for.
The most common cause is low humidity combined with dry indoor air, particularly in winter when central heating is running. The leaf tips are the furthest point from the roots, so they're the first to show the strain when the plant can't pull enough moisture. This is especially common with ferns, calatheas, and peace lilies. The fix is to increase humidity (a pebble tray, grouping plants together, a small humidifier) rather than watering more. More water to the roots doesn't help if the air around the leaves is too dry.
The second most common cause is inconsistent watering — specifically, the plant drying out completely between waterings. The roots suffer, the vascular system struggles, and the tips are the first to show it. This is different from underwatering in general; it's the boom-and-bust cycle that does the damage. Consistent moderate moisture is usually better than irregular heavy watering.
Brown tips can also come from tap water that's high in fluoride or salts. Spider plants and dracaenas are particularly sensitive. If your water is hard and your spider plant has been crispy at the tips for months, try switching to filtered water or water that's been left to stand overnight.
Cold drafts from windows or air conditioning vents cause similar symptoms and are easy to miss. Plants that sit on a windowsill in summer and get moved away in winter might be sitting somewhere that gets cold air from a draft you've stopped noticing.
What brown tips are rarely caused by: overwatering. Overwatering typically shows as yellowing, not browning. If the leaves are yellow and soft, that's overwatering. If they're brown and dry at the edges and tips, look at humidity, consistency, and water quality first.