Why is my Aloe plant turning brown?

Soft brown rot versus dry brown scorch

The single most useful thing about a browning Aloe is that the brown itself comes in two distinct textures, and they point to opposite problems. Wet, soft, water-soaked brown means rot from too much water. Dry, crispy, papery brown means scorch from too much sun, cold, or thirst. Pressing the discolored tissue with a finger tells you which one you have before you change anything.

Overwatering is the top cause. Aloe vera is a succulent that stores its own water and is built for long dry spells, so soggy soil starves the roots of oxygen and they rot. That rot then travels up into the short stem and lower leaves as brown, mushy, sometimes smelly tissue. The University of Missouri Botanical Garden notes that overwatering is one of the most common ways houseplants are killed, and Aloe, with its desert wiring, is especially unforgiving of a pot that stays wet. The giveaways are browning that starts at the base, soft squishy texture, and soil that has stayed damp for days, often in a pot with no drainage.

Worked example: brown patch after a windowsill move

You moved an Aloe from a shaded spot straight onto a bright south-facing sill, and within a few days a brown, reddish, crispy patch appeared on the leaves facing the glass. Press it: it is dry and papery, not soft, and the soil is dry too. Dry brown on the sun-facing side after a sudden light increase is sunburn, not rot. You pull the plant back a couple of feet from the glass and reintroduce direct sun gradually over about two weeks. The scorched tissue stays brown, since it cannot heal, but no new burning appears and you trim the worst leaves once new growth establishes.

Other causes that brown an Aloe

• Sunburn. Brown or reddish-brown dry patches on the side facing the window after a sudden move into intense direct sun.
• Cold damage. Leaves turn brown, mushy, or translucent after exposure to temperatures below about 50F (10C) or a cold draft near a window.
• Underwatering. Tips and edges go thin, brown, and crispy while the leaves curl and the soil is bone dry.
• Salt or fertilizer buildup. Brown leaf tips with a white crust on the soil follow heavy feeding or hard tap water.

How to fix it

1. Check the base. Press the lower leaves and stem. If they are soft and brown, treat it as rot and act fast; if firm, the problem is light, cold, or thirst.
2. Stop watering. Let the soil dry out completely, and only water again when it is bone dry several inches down.
3. Cut out rot. If the base is mushy, unpot the plant, slice off all soft brown tissue with a clean blade, and let the cut callus for a day or two.
4. Repot in gritty mix. Use a cactus or succulent soil in a pot with drainage holes, and never let it sit in standing water.
5. Fix the light. Give bright light but move it back from intense midday glass, acclimating to direct sun slowly over two weeks.
6. Keep it warm. Hold the plant above 50F (10C) and away from cold drafts and frosty windows.
7. Flush salts. If you see crust on the soil, water thoroughly to flush it through, then cut back on fertilizer and feed only during active growth.