What’s the problem?
There is a chalky white crust on the top of my spider plant’s potting mix, and the leaf tips are turning brown. Why is this happening and how do I fix it?
Diagnosis
This is a buildup of mineral salts from hard tap water or fertiliser. As water evaporates, salts are left behind and come to the surface. Over time, they concentrate around the roots, drawing out moisture and scorching sensitive tissues, which shows up as brown, papery leaf tips and edges. It can also throw off the soil pH, so plants struggle to absorb nutrients.
Prescription
Run tepid tap water through the mix for a few minutes until plenty of water drains out. Repeat a week later. If the crust is heavy or the mix is compacted, repot in fresh, free-draining, peat-free compost and clean the pot before reusing it. Trim crisped tips with clean scissors, mirroring the natural shape of the leaf. Switch to rainwater, filtered water or boiled and cooled tap water. Feed only in spring and summer.
Prevention
Flush containers monthly to prevent salt buildup. Water deeply but less often, and always empty saucers of residue. Match your fertiliser use to growth periods and if your water is very hard, use rainwater.
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