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Anthurium has a small number of problems that account for nearly everything people ask about. Find your symptom here, then read the section named in the last column rather than treating the leaf you can see.
| What you see | Most likely cause | Where to read |
|---|---|---|
| Lower leaves going yellow one after another | Roots too wet, or the plant is simply hungry | Yellowing lower leaves |
| Healthy leaves but no flowers for months | Not enough light, or too much nitrogen | Why it stopped flowering |
| Brown crisp leaf edges | Dry air, a draft, or fertilizer salts | Brown edges and tips |
| The whole plant limp with wet compost | Root rot | Root rot and how to save the plant |
| Fine webbing and pale stippling on leaves | Spider mites | Pests worth knowing |
| Sticky leaves and white fluff in the leaf joints | Mealybugs | Pests worth knowing |
| Dark water soaked patches spreading fast | Bacterial blight | Diseases |
Yellowing lower leaves
This is the most common anthurium question there is, and it has three different answers. Losing the single oldest leaf every couple of months is normal turnover and needs nothing done. Losing several in a few weeks is not.
If the mix has been staying wet, the cause is the roots. Let the pot dry hard, then slide the plant out and look: firm pale roots mean you can simply water less, brown hollow roots mean go to the root rot section. If the mix has been drying properly and the leaves are yellowing anyway, particularly with a pale green cast on the newer leaves too, the plant is short of feed and probably overdue a repot.
- Check the pot before you cut anything Push a finger in. Wet at depth after a week points at the roots. Dry and light points at feeding or pot exhaustion instead.
- Remove a fully yellow leaf Once a leaf is more than half yellow it will not recover and it is drawing resources. Cut the stalk at the base with clean snips rather than pulling it off.
- Count how many in how long One old leaf a month is normal. Three in a fortnight is a root problem until proven otherwise.
Yellowing that starts at the leaf edge and moves inward with a brown dry margin is usually fertilizer salts or dry air, not overwatering. Flush the pot with plain water and reconsider the feed.
Why it stopped flowering
An anthurium that grows leaves happily but never flowers is almost never diseased. It is short of one of three things, and they are easy to separate.
Light comes first: a plant three feet or more from a window keeps its leaves and stops flowering, and moving it to the glass changes that within a couple of months. Feeding comes second: a general houseplant feed high in nitrogen builds leaves at the expense of flowers, so switch to a feed with a higher phosphorus figure at quarter to half strength every two to four weeks in the growing season. Temperature comes third: below about 65F (18C) the plant simply will not initiate flowers, however good the light is.
| Condition | Signal you would also see | What to change |
|---|---|---|
| Too dark | New leaves smaller, longer stalks, plant leaning | Move to an east window or right up to the glass |
| Too much nitrogen | Large lush leaves, vigorous growth, no buds | Switch to a bloom feed at half strength |
| Too cold | Growth has visibly stalled | Move somewhere that holds 68F (20C) or more |
| Pot far too large | The mix stays wet for weeks after watering | Repot down a size into fresh chunky mix |
| Exhausted mix | It has been three years or more in the same pot | Repot into fresh mix in late spring |
A spathe that opens green rather than colored, or opens small, usually means light. Cut the spent flower stalk at the base once it fades so the plant is not carrying it.
Root rot and how to save the plant
Root rot is what kills most anthuriums, and it is recoverable if you act on the day you notice it. The signal is a plant that looks thirsty while the compost is wet, often with a sour smell from the pot.
- Unpot it and wash the roots Slide the plant out and rinse the mix off under a tap so you can see what you have. Do not guess from the top.
- Cut away everything soft Firm pale roots stay. Brown, soft roots that slide apart between finger and thumb come off with clean snips, back to healthy tissue.
- Reduce the top to match If you removed half the roots, remove roughly half the leaves. The remaining roots cannot support the old leaf area.
- Repot into fresh chunky mix, one size down Never back into the same wet mix and never into a larger pot. Less mix around the roots is what you want now.
- Water once, then wait Water it in and then leave it until the mix is genuinely dry. Keep it warm, bright and out of direct sun while it rebuilds roots.
Do not feed a plant that has just had rot cut out. Fertilizer on freshly cut roots does damage. Wait until you see a new leaf, usually four to six weeks.
Pests worth knowing
Anthurium picks up the standard indoor pests, and all four below are easier to catch early than to clear later. Check the leaf undersides and the joints where leaf stalks meet the crown once a fortnight.
| Pest | How you spot it | What to do |
|---|---|---|
| Spider mites | Fine pale stippling, webbing in leaf joints, worst in dry heat | Rinse both leaf surfaces, raise humidity, treat with insecticidal soap weekly for three weeks |
| Mealybugs | White cottony fluff in the crown and leaf joints, sticky leaves | Dab each one with a cotton bud dipped in rubbing alcohol, then treat the whole plant |
| Scale | Small hard brown discs on stalks and leaf undersides | Scrape off by hand, then treat with a horticultural oil twice, two weeks apart |
| Thrips | Silvery streaks, deformed new leaves, spoiled flowers | Remove affected flowers, treat repeatedly, isolate the plant |
| Fungus gnats | Small flies from the surface after watering | Let the surface dry hard between waterings. They indicate overwatering more than they cause harm |
Isolate any newly bought plant for three weeks before it joins the others. Almost every indoor infestation arrives on a new plant.
Diseases
Anthurium has one disease worth taking seriously indoors. Bacterial blight shows as water soaked patches, often starting at a leaf margin, that spread outward with a yellow halo and can take a plant down in a fortnight in warm humid conditions. It spreads on wet leaves and on cutting tools.
There is no home cure. Cut out affected leaves well beyond the visible damage, sterilize the blade between every cut, stop misting entirely, improve the airflow around the plant, and isolate it from everything else. If more than half the plant is involved, take a clean division from an unaffected part if you can and discard the rest rather than trying to nurse it.
Anthurium sap contains calcium oxalate and irritates skin, mouth and eyes. Wear gloves when you cut, wash your hands afterwards, and keep cut material away from children and pets.
Keeping a record
When something goes wrong, note the date, the symptom, what the mix felt like, and what you changed. Anthurium responds slowly, so the effect of today's change appears in three or four weeks and you will not remember what you did.
Note the date you first saw each pest as well. Mites and thrips return at roughly the same point each year in the same room, and knowing that date is what lets you start checking a fortnight before instead of a month after.