Plant Problems: Yellow Leaves, Brown Tips, Drooping, Powdery Mildew and Root Rot

Most sick plants show one of a handful of symptoms, and each symptom has a short list of likely causes. Pick the problem you see, check the signs for each cause, and fix the one that fits before reaching for a spray.

This is general plant-care guidance, not a laboratory diagnosis. Want an answer for your plant? Pick your symptoms in the free symptom checker or run a photo health check with the PlantoScan plant doctor.

Why are my plant's leaves turning yellow?

Yellow leaves are the most common plant complaint and have the widest range of causes. Where the yellowing starts tells you a lot: older, lower leaves usually point to watering, nitrogen or simple ageing, while yellow new leaves with green veins point to a micronutrient problem such as iron.

Before feeding or repotting, check the soil. Wet soil days after watering is the single most common cause of yellow leaves on houseplants, and fertilizer won't fix it.

Quick check: Is the soil still wet 2 in (5 cm) down several days after watering? Start with overwatering.

Likely causes

Overwatering and root rot

Watering

Soil that stays wet starves roots of oxygen, and rot fungi move in. The plant wilts even though it has water, because damaged roots can no longer take it up.

How to check

  • Push a finger or wooden skewer 2 in (5 cm) into the soil. Wet, cool soil several days after watering points to overwatering.
  • Slide the plant out of its pot. Healthy roots are firm and white to tan; rotten roots are brown or black, slimy, and the outer layer slips off.
  • Confirm the pot has a drainage hole and isn't standing in a saucer of water.

What to do

  • Stop watering until the top 1–2 in (2.5–5 cm) of soil is dry — fully dry for succulents and cacti.
  • If roots are rotten, trim every soft root with clean scissors and repot into fresh, well-draining mix in a pot with drainage, sized to the remaining healthy roots.
  • Skip fertilizer until new growth appears. If the stem base is mushy, root healthy cuttings as a backup.

Underwatering (drought stress)

Watering

A plant that runs dry wilts, curls its leaves to save water and sacrifices older leaves. It usually perks up within a few hours of a thorough watering.

How to check

  • Check the soil 2 in (5 cm) down: dust-dry soil and a pot that feels light confirm thirst.
  • Look for soil shrinking away from the pot wall — water then runs down the gap without wetting the root ball.

What to do

  • Water slowly until it drains from the bottom. If water runs straight through, set the pot in a basin of water for 20–30 minutes to rewet the root ball.
  • Water most tropical houseplants when the top 1–2 in (2.5–5 cm) is dry; check more often in summer and near heaters.
  • Trim fully crisp leaves — brown tissue does not turn green again.

Nitrogen deficiency

Nutrition

Plants move nitrogen from old leaves to new growth when supply runs low, so yellowing starts evenly on the oldest leaves and creeps upward.

How to check

  • Yellowing is even across the whole leaf (not between veins) and starts at the bottom of the plant.
  • The plant hasn't been fed for months or has sat in the same potting mix for 2 years or more. Rule out wet soil and root rot first — they cause the same yellowing.

What to do

  • Feed with a balanced fertilizer at the label rate during spring and summer, or repot into fresh mix.
  • Existing yellow leaves won't recover; new growth should come in greener within a few weeks.

Iron or magnesium deficiency (chlorosis)

Nutrition

Yellow leaf tissue between green veins is called interveinal chlorosis. On new leaves it usually points to iron; on older leaves, magnesium. High soil pH often locks these nutrients up.

How to check

  • Hold a leaf to the light: veins stay green while the tissue between them turns yellow.
  • Iron chlorosis appears on the newest leaves first; magnesium on older ones. Acid-loving plants in alkaline soil or hard water are most prone.

What to do

  • Use a fertilizer that lists micronutrients, including chelated iron, at the label rate.
  • For garden plants, test soil pH before adding amendments; many acid-loving shrubs want a pH of about 5.0–6.0.

Too little light

Environment

Light-starved plants stretch toward the window with long gaps between leaves, push out small pale leaves and let variegated leaves revert to plain green.

How to check

  • Stems lean toward the window and the spaces between leaves (internodes) are longer on new growth than old.
  • The plant sits more than about 6–8 ft (2 m) from a window, or in a north-facing room.

What to do

  • Move the plant closer to a bright window or add a full-spectrum grow light for 10–12 hours a day.
  • Stretched stems won't shorten: prune them back to encourage bushier growth once light improves. Water less until then, since plants in dim light use less.

Normal leaf aging

Normal

Every plant sheds its oldest leaves over time. One or two bottom leaves yellowing slowly while new growth looks healthy is normal.

How to check

  • Only the oldest one or two leaves are yellow, and the rest of the plant looks healthy.
  • New leaves are emerging at a normal size and color.

What to do

  • No treatment needed. Pull the leaf off once it detaches easily, or trim it at the base.

Often seen on: Peace Lily, Weeping Fig, Pothos, Monstera Deliciosa.

Why do my plant's leaves have brown, crispy tips?

Brown, crispy tips and edges mean the far ends of the leaf are losing water faster than the plant can supply it. Dry indoor air, uneven watering and a build-up of fertilizer salts are the usual reasons, and thin-leaved tropical plants such as calatheas, prayer plants and ferns show it first.

Brown tissue never turns green again. Fix the cause, then trim the tips with clean scissors following the leaf's natural shape; new leaves will show whether the change worked.

Quick check: White crust on the soil or pot rim? Flush the soil before anything else.

Likely causes

Low humidity or dry air

Environment

Thin-leaved tropical plants such as calatheas, ferns and prayer plants brown at the tips when indoor air is dry, especially in heated winter rooms.

How to check

  • Browning stays on the tips and edges while the rest of the leaf is green and firm.
  • The plant sits near a heater, fireplace or air-conditioning vent, or a hygrometer reads below about 40%.

What to do

  • Move the plant away from vents, group plants together or run a humidifier aiming for about 50% relative humidity.
  • Trim brown tips with clean scissors, following the leaf's natural shape. Misting only raises humidity for minutes.

Underwatering (drought stress)

A plant that runs dry wilts, curls its leaves to save water and sacrifices older leaves. It usually perks up within a few hours of a thorough watering. How to check and fix it

Fertilizer burn or salt buildup

Nutrition

Excess fertilizer salts and hard-water minerals collect in the soil and draw water out of the roots, which scorches leaf tips and margins.

How to check

  • Look for a white or yellowish crust on the soil surface or the pot rim.
  • Think back: fertilizer at full strength, fertilizer on dry soil, or feeding through winter all raise salt levels.

What to do

  • Flush the soil: run about 2–3 times the pot's volume of water through it and let it drain fully.
  • Resume feeding at half the label rate during active growth only. Repot into fresh mix if the crust returns quickly.

Sunburn (leaf scorch)

Environment

Leaves that suddenly get more direct sun than they're used to bleach white or tan in dry, papery patches — most often after a move outdoors or to a south window.

How to check

  • Damage sits only on the leaves or leaf sides facing the sun, and appeared within days of a change in position.
  • Patches are dry and papery rather than soft, with no halo or spreading ring.

What to do

  • Move the plant to bright, filtered light and reintroduce direct sun gradually over 1–2 weeks.
  • Scorched patches are permanent; trim leaves that are more than half damaged once new growth appears.

Often seen on: Peacock Plant, Prayer Plant, Boston Fern, Spider Plant.

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Why is my plant drooping or wilting?

A drooping plant is short of water in its leaves, but that doesn't always mean the soil is dry. Roots damaged by rot can't take up water either, so an overwatered plant wilts just like a thirsty one. The soil tells them apart: dry and light means thirst, wet and heavy means the roots are struggling.

Sudden drooping after a cold night, a move or repotting is usually shock, and the plant recovers once conditions are stable.

Quick check: Lift the pot: very light means water now; heavy and wet means check the roots instead.

Likely causes

Underwatering (drought stress)

A plant that runs dry wilts, curls its leaves to save water and sacrifices older leaves. It usually perks up within a few hours of a thorough watering. How to check and fix it

Overwatering and root rot

Soil that stays wet starves roots of oxygen, and rot fungi move in. The plant wilts even though it has water, because damaged roots can no longer take it up. How to check and fix it

Cold or draft damage

Environment

Most tropical houseplants are damaged by temperatures below about 50°F (10°C). Chilled leaves turn dark and glassy within a day or two, then collapse.

How to check

  • The plant touched a cold window, sat near an outside door, rode home in a cold car or stayed outdoors on a chilly night.
  • Damage appeared suddenly and is worst on the side that faced the cold.

What to do

  • Move the plant to a steady 60–80°F (16–27°C) spot away from drafts.
  • Wait for new growth before cutting back so you can see what survived; for garden plants, prune after your last frost date. Water sparingly while it recovers.

Relocation or transplant shock

Environment

Moving, repotting or bringing a plant home from the store changes its light, temperature and humidity at once. Figs in particular often drop leaves in response.

How to check

  • The plant was moved, repotted or bought within the last 2–4 weeks.
  • Roots are firm and healthy and there are no pests or spots.

What to do

  • Pick a good spot and leave the plant there; keep watering consistent.
  • Skip fertilizer for 4–6 weeks. New leaves are the sign it has settled in.

Often seen on: Peace Lily, Fiddle Leaf Fig, Hydrangea, Tomato Plant.

What are the white spots on my plant's leaves?

A white or grey powder that wipes off with a finger is almost always powdery mildew, a fungal disease that loves still air and crowded plants. White cottony tufts in the leaf joints are different: those are usually mealybugs, small sap-sucking insects.

Both spread to neighbouring plants, so move the affected plant away from the others while you treat it.

Quick check: Rub a spot: powder that wipes away is mildew; a waxy, cottony tuft with a small insect inside is a mealybug.

Likely causes

Powdery mildew

Fungal diseaseSpreads: isolate the plant

Powdery mildew coats leaves in white or gray powder that rubs off. Unlike most fungi it doesn't need wet leaves — still air, crowding and humid nights favor it.

How to check

  • Rub a patch with a finger: the powder wipes away, leaving yellowed tissue beneath.
  • It starts on upper leaf surfaces of susceptible plants such as begonias, roses, squash, zinnias and phlox.

What to do

  • Remove the worst leaves, space plants out and improve air flow and light.
  • Treatments based on potassium bicarbonate, horticultural oil or sulfur can slow it — test on one leaf first, follow the label, and don't spray oils above about 90°F (32°C).

Mealybugs

PestSpreads: isolate the plant

Mealybugs are slow, oval insects about 1/8 in (3 mm) long covered in white wax. They hide in leaf joints, under leaves and sometimes on roots.

How to check

  • Look in leaf axils, along stems and under leaves for white fluff that contains small segmented insects.
  • Unpot suspicious plants: white patches on the root ball are root mealybugs.

What to do

  • Isolate the plant and dab each mealybug with a cotton swab dipped in 70% rubbing alcohol (test a leaf first).
  • Follow with insecticidal soap or horticultural oil weekly for several weeks. Heavy infestations on small plants are often easier to discard.

Often seen on: Polka Dot Begonia, Garden Phlox, Zinnia, Zucchini Plant.

How do I know if my plant has root rot?

Root rot starts below the soil, so the first visible signs are often yellowing lower leaves, wilting in wet soil, a mushy stem base or fungus gnats around the pot. The only way to be sure is to look at the roots: healthy roots are firm and white to tan, rotten ones are brown or black, soft and often smell sour.

Caught early, most plants recover once the rotten roots are cut away and the plant is repotted into fresh, well-draining mix. If the stem base itself is soft, take cuttings from healthy growth as a backup.

Quick check: Slide the plant out of its pot and look: soft, dark, smelly roots confirm rot.

Likely causes

Overwatering and root rot

Soil that stays wet starves roots of oxygen, and rot fungi move in. The plant wilts even though it has water, because damaged roots can no longer take it up. How to check and fix it

Fungus gnats

Pest

Fungus gnats are small dark flies about 1/8 in (3 mm) long that breed in constantly moist potting mix. Adults are harmless; larvae can damage seedlings and cuttings.

How to check

  • Weak-flying gnats rise from the soil when you water or move the pot.
  • A yellow sticky card or a slice of raw potato on the soil for a day shows adults and larvae.

What to do

  • Let the top 1–2 in (2.5–5 cm) of soil dry between waterings, or water from below.
  • Trap adults with yellow sticky cards and treat larvae with a soil drench containing Bti (Bacillus thuringiensis israelensis).

Often seen on: Jade Plant, Zz Plant, Snake Plant, Aloe Vera.

Before you spray anything

  • Confirm the cause first: most problems on houseplants are watering or light, which no spray fixes.
  • Isolate plants with pests or a spreading disease so the problem doesn't move to the rest.
  • Use any treatment exactly as its label says, test it on one leaf first, and keep children and pets away from treated plants. If your pet ate a plant, contact your vet or animal poison control.

Frequently asked questions

Why are the leaves on my houseplant turning yellow?
Most often because the soil stays too wet, which damages the roots. Other common causes are underwatering, a lack of nitrogen after months without feeding, too little light, or simply old lower leaves being shed. Check the soil moisture first, then look at where on the plant the yellowing starts.
Should I cut off brown leaf tips?
Yes, if you like. Brown tissue won't recover, so trimming it with clean scissors is purely cosmetic and doesn't harm the plant. Fix the cause too, usually dry air, irregular watering or fertilizer salts, or the tips will brown again.
Can a plant recover from root rot?
Often, if enough healthy roots remain. Cut away every soft, dark root, repot into fresh, well-draining mix in a pot with a drainage hole, and water only when the top of the soil has dried. If the stem base is rotten, root healthy cuttings instead.
Is powdery mildew harmful to people or pets?
Powdery mildew is a plant disease. Some treatments used against it, such as sulfur or oils, should be kept away from children and pets and used exactly as the label says. If your pet ate a plant or a treated plant, contact your vet or animal poison control.
How can I tell what's wrong with my plant from a photo?
Take a clear photo of the affected leaves in daylight and run a health check in the PlantoScan app, which suggests the likely cause and next steps. On the web, the free symptom checker ranks likely causes from the symptoms you pick.
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