Brown leaves are the most common thing gardeners bring to us, and the pattern of the browning usually tells you the cause before you check anything else. Brown tips mean something different from brown edges, which mean something different again from whole leaves going brown at once. In Australian gardens the usual suspects are heat, wind, water and salt rather than disease, and most of them are fixable in a weekend.
Quick diagnosis
| What you see | Most likely cause | First thing to do |
|---|---|---|
| Brown crispy tips only | Dry air, underwatering, or salt build-up | Water deeply; flush pots with plenty of water |
| Brown edges, green centre | Heat or wind scorch, or fertiliser burn | Check recent feeding and afternoon sun exposure |
| Papery bleached patches | Sunburn, usually after a hot spell | Provide afternoon shade; do not remove all damaged leaves at once |
| Whole leaves brown and dropping | Root problem - too wet or too dry | Dig down 100 mm and feel the soil |
| Brown from the lowest leaves up | Overwatering or root rot | Check drainage before anything else |
| Brown spots with yellow halos | Fungal leaf spot | Improve airflow, remove affected leaves |
| Brown after a cold night | Frost damage | Wait until spring before pruning |
The Australian causes, in order of likelihood
Heat and sunburn
Australian summer sun is intense enough to burn leaves that would be perfectly happy in a European garden, and the damage arrives fast - a single 40°C day with hot wind can scorch a plant that looked fine the morning before. It shows as bleached or papery patches on the most exposed leaves, worst on the western side of the plant.
Afternoon sun does the damage, not morning sun. Plants against a west-facing wall or light-coloured paving cop reflected heat as well as direct sun. Move sensitive plants, provide temporary shade cloth through heatwaves, and water deeply the evening before a forecast hot day rather than during it.
Watering, in both directions
Underwatering browns leaf tips and edges first, and the plant usually wilts before it browns. Overwatering browns whole leaves, starting from the bottom, and the soil stays damp days after watering. The two look similar on the leaf, which is why the reliable test is the soil, not the foliage - push a finger 100 mm down before deciding anything.
Water deeply and less often rather than lightly and daily. Shallow frequent watering keeps roots near the surface, where they cook in the first hot week of summer.
Wind and salt
Hot dry inland wind desiccates leaves faster than the roots can replace the moisture, browning the edges of the most exposed foliage. On the coast the same effect comes with salt, which burns leaf margins on anything that is not salt tolerant. Both are position problems rather than health problems - the answer is a windbreak, or a tougher plant in that spot.
Fertiliser burn
Too much fertiliser, or fertiliser applied to dry soil, draws moisture out of the roots and browns leaf edges within days. It is common after someone feeds a struggling plant to help it. If browning follows a feed, water heavily to flush the soil and do not fertilise again until the plant recovers.
Frost
In Melbourne, Canberra, Adelaide Hills, Tasmania and frost-prone inland districts, overnight cold blackens or browns soft growth, usually on the top and outer edges where the plant is most exposed. Leave the damage in place over winter - it shelters the growth beneath it - and prune back to live wood in spring.
Root problems and drainage
If whole leaves brown and drop while the soil stays wet, the roots are the problem. Heavy clay, a pot with a blocked drainage hole, or a saucer left full will all cause it. Australian summer storms can waterlog a bed for days. Check drainage before treating for anything else, because a plant with rotting roots cannot take up water no matter how much you give it.
Brown leaves on indoor plants
Indoors, brown crispy tips are almost always low humidity, which is worse in an air-conditioned Australian home than most people realise. Group plants together, stand pots on a pebble tray, or move them somewhere naturally more humid.
The second common indoor cause is salt build-up from fertiliser and tap water, which shows as browning tips and a white crust on the soil surface or pot rim. Flush the pot thoroughly every few months - water until it runs freely from the base, several times over.
What to do next
- Check the soil first. Finger 100 mm down. Dry, damp or soaking tells you more than the leaves do.
- Look at the pattern. Tips, edges, whole leaves or spots each point somewhere different - use the table above.
- Think about the last fortnight. A heatwave, a windy few days, a fertiliser application or a cold snap usually explains it.
- Check the position. Western sun, reflected heat off paving, or an exposed corner will keep causing the problem until the plant is moved.
- Do not strip every damaged leaf. Even browned foliage shades the growth beneath it. Remove leaves gradually as new growth replaces them.
- Fix the cause, then wait. Damaged leaves never turn green again. Recovery shows in the new growth, which takes weeks.
Preventing it
- Match the plant to the position. Most brown-leaf problems are a plant in the wrong spot rather than a plant that is unwell.
- Mulch to 50-75 mm, kept clear of stems. Mulch moderates soil temperature and moisture more than any watering routine.
- Water deeply, early in the morning, so plants are hydrated before the heat arrives.
- Improve drainage before planting, especially in clay soils.
- Feed lightly and onto moist soil, never onto dry ground.
- Plan for heatwaves. Shade cloth over vulnerable plants for two or three days costs little and saves a season of recovery.
Frequently asked questions
Why are the tips of my plant's leaves turning brown?
Brown tips usually mean the plant is not getting enough water to the leaf edges - from dry soil, dry air, or salt build-up in the potting mix restricting uptake. Indoors, low humidity from air conditioning is the most common cause. Water deeply, and flush pots thoroughly every few months to clear accumulated salts.
Should I cut off brown leaves?
Not all at once. Damaged leaves still shade the stems and growth beneath them, which matters during an Australian summer. Remove them gradually as new growth comes through, and after frost leave the damage until spring.
Can a brown leaf turn green again?
No. Once leaf tissue browns it is dead and will not recover. Judge whether your fix is working by watching the new growth, not the damaged leaves.
How do I tell overwatering from underwatering?
Check the soil rather than the leaves, because the foliage looks similar either way. Push a finger 100 mm down: soaking soil with browning lower leaves means overwatering, while dry soil with wilting and crispy edges means underwatering. Overwatered plants often also smell sour at the roots.
Why did my plant brown suddenly after a hot day?
Sunburn and heat stress, which can happen in a single day above 40°C, especially with hot wind. Damage appears worst on the western side. Water deeply the evening before forecast heat, and shade vulnerable plants through the worst of it.
My plant browned after I fertilised it. What happened?
Fertiliser burn, most likely from feeding onto dry soil or applying too much. The salts draw water out of the roots. Flush the area heavily with water and hold off feeding until the plant is growing normally again.
Still not sure?
If the browning does not match anything above, or it keeps returning after you have corrected watering and position, it is worth checking for pests and disease. Our guide to understanding leaf burn covers scorch in more detail, and identifying common plant pests and diseases covers the fungal and insect causes.
Sometimes the honest answer is that the plant is in the wrong place. If a spot keeps killing things, browse our hardy plants for tough spots for species that will actually cope with it.
