Why are my Monstera leaves turning brown?

Where the brown is, and what it feels like

The single most useful diagnostic with a browning Monstera (usually Monstera deliciosa, sometimes the smaller adansonii) is to look at where the brown sits and how it feels. Crispy brown edges and tips that crumble between your fingers mean the leaf dried out, from thirst, low humidity, or salt. Soft, dark brown or mushy patches mean the opposite problem, too much water and failing roots. Bleached or tan scorch on the one side facing a bright window is sun damage. Small brown spots ringed with yellow can mean a different issue again. Reading the location and texture first stops you from watering a rotting plant or drying out a thirsty one.

Most likely cause: drying out at the edges

The most common cause of brown Monstera leaves is the leaf transpiring faster than the roots can keep up, driven by underwatering and dry indoor air. Monsteras come from the humid forests of southern Mexico and Central America, where they enjoy roughly 60 percent humidity or more. In a heated or air-conditioned room that can fall below 40 percent, and combined with soil left dry too long, the thin leaf margins dehydrate and die back into crispy brown edges. Iowa State University Extension confirms that brown leaf tips and edges on houseplants commonly trace back to dry soil, low humidity, and salt accumulation rather than disease.

Confirm it by feel and pattern: the browning is dry and crisp, starts at the edges and tips, and the soil is bone dry, sometimes shrunk away from the pot wall. Water thoroughly until it drains, raise humidity toward 50 to 60 percent, and the next leaves should come in clean. Existing brown areas will not turn green again.

Other causes

These rank below dryness but each leaves a distinct mark.

• Root rot from overwatering. The opposite extreme. Browning is soft, dark, and mushy rather than crispy, the soil stays wet for over a week, and the base may smell sour.
• Too much direct sun. Harsh midday rays through unfiltered glass scorch the leaf. Look for dry, bleached, or tan-brown patches concentrated on the side facing the window.
• Fertilizer or salt buildup. Excess feed and hard-water salts burn the tips brown and may leave a white crust on the soil surface, often showing up soon after feeding.
• Cold drafts or temperature swings. Exposure to a chilly window below 55 degrees Fahrenheit (13 degrees Celsius), an AC vent, or a hot radiator browns patches and edges, sometimes with a darkened, water-soaked look.

A worked example

Suppose your Monstera deliciosa sits a few feet from a radiator in winter and several lower leaves have crispy brown edges. You pinch one: it crumbles, dry and papery, not soft. The soil is bone dry two inches down and has pulled slightly from the pot, and a cheap hygrometer reads 32 percent. That set of clues, crispy edges plus dry soil plus low humidity, points to dehydration, not rot. You soak the pot thoroughly, move the plant away from the radiator, and run a small humidifier nearby to hold 50 to 60 percent. You trim the dead edges back to the leaf shape, leaving a thin brown margin so you do not cut into live tissue, and watch the new growth open clean.

How to fix it

1. Diagnose the brown. Pinch the brown tissue: crispy means too dry, soft and dark means too wet. Let this guide everything below.
2. Water consistently. Soak until water drains from the bottom, then water again only when the top 1 to 2 inches are dry.
3. Raise humidity. Aim for 50 to 60 percent with a humidifier or a pebble tray, especially in heated or air-conditioned rooms.
4. Adjust the light. Move it out of harsh direct sun into bright indirect light, acclimating it to any brighter spot over a week.
5. Flush the soil. If you suspect salt buildup, run water through the pot several times to leach out excess fertilizer and salts, then ease off feeding.
6. Shelter from extremes. Keep it away from cold drafts, AC vents, radiators, and single-pane winter windows, ideally above 60 degrees Fahrenheit (16 degrees Celsius).
7. Trim and inspect. Cut off dead brown tissue with clean shears, and if browning is soft, unpot and trim any mushy roots before repotting in fresh chunky mix.