White crust and salt buildup
A white crust on the soil surface, the pot rim, or the outside of a clay pot means soluble salts have been accumulating in the mix — from fertilizer, from hard water, or from both. As salts build up, roots take up water less easily, and leaf tips and edges are often the first parts to show damage.
Salt buildup is a slow problem with a simple fix, but it is easy to misread as underwatering: adding more fertilizer to a plant already suffering from salts makes it worse.
General beginner information only — not a substitute for advice from your local agricultural extension service. For edible plants, use only a product that is labelled for that particular edible crop, for indoor use, and follow any harvest interval on its label; try non-chemical steps first, and never use a product that is not labelled for indoor use on that plant.
Checklist to diagnose
- Is there a white crust on the mix surface, the pot rim, or drainage holes?
- Are leaf tips or edges brown and crispy while the mix itself is not dry?
- Has the plant been fed often, or at rates above the product label?
- Is your tap water hard, or has softened water been used?
- Has the plant been in the same mix for a long time without flushing or repotting?
Rescue steps
- Scrape off the visible crust and the top layer of mix if it is heavily crusted.
- Flush the pot with plain water until water runs freely from the drainage holes, let it drain, and repeat the flush so salts wash out rather than resettle.
- Empty the saucer so the plant never sits in the flushed water.
- Hold off feeding until new growth looks healthy, and then feed only at the product's labelled rate, less often rather than more.
- If the mix is old and compacted as well as salty, repot into fresh mix when the plant is actively growing — see the repotting page.
When to give up
- Salt damage alone rarely kills a plant once flushing is done. Discard only if roots are rotted or the plant shows no new growth after flushing and steady care.
Plants on this site
This page gives general indoor advice: it applies to indoor-grown plants generally and is not a claim about any particular plant on this site.