Salt damage
Leaf burn and stunted growth caused by too much salt in the soil or water, from sea spray, road salt, hard water or heavy fertiliser use.
Also known as: Salt burn, Salt injury
Symptoms and identification
Leaf tips and edges turn brown and scorched, starting on older leaves, and plants look stunted and wilt even when the soil is moist. A white, crusty layer may form on the soil surface or the outside of clay pots. Roots may be small and dark.
Causes
Salts build up when soil is watered with salty or very hard water, when too much fertiliser is used, or when drainage is poor and water evaporates from the surface. Winter road salt and coastal wind carry salt to plants.
Organic treatment
Flush the soil or pot slowly with plenty of clean water, letting it drain freely, to wash salts down and out. Scrape off crusts, repot houseplants into fresh mix if salts are severe and trim burnt leaf tips.
Prevention
Use rain or low-salt water where you can, water thoroughly so that excess drains out, and avoid over-fertilising. Do not use rock salt near planting beds, and improve soil drainage with organic matter.
Chemical treatment (use with care)
On heavy soils, gypsum can help displace sodium, but only use it after a soil test shows sodium is the problem.