A plant that is going wrong usually shows one sign at a time: a yellow leaf, a limp stem, brown edges creeping in from the tip. The hard part is that the same sign can come from several different causes, and the wrong guess means watering a plant that is already too wet, or moving to a window that makes a light problem worse.
What the checker does
You tell it what you are seeing and what plant it is seeing it on. It comes back with a ranked list of likely causes, starting with the one that fits the symptom and plant combination best, and works down from there. Each cause comes with its pot and drainage implications flagged where they apply, because a lot of what looks like disease or pest damage is actually the container doing something the plant cannot cope with.
It never names a treatment product. Where the next step is a care change, pot swap or watering adjustment, it says so and points you to the relevant care guide, including the individual plant pages such as monstera care, peace lily care and calathea care, each of which gives watering depth and frequency for the plant in question.
Why pot and drainage keep coming up
Yellowing lower leaves, a sour smell from the soil, roots that look dark and soft rather than firm and pale: these are watering and drainage symptoms far more often than they are disease symptoms, and the pot is usually part of the cause. A decorative pot with no hole, a saucer that stays full, or a material that holds onto moisture longer than the plant wants will all produce leaf symptoms that look like something else is wrong.
Where a result points this way, it flags the pot and drainage angle specifically. The drainage guide covers what to do about a sealed pot or an overfull saucer, and the planter material guide explains which materials hold moisture and which let it go, so you can tell whether the container is working against the plant before you change anything else.
When the pot is the wrong size
A plant can also show stress because it has outgrown its pot, or because it was moved into one too large too soon. Roots that circle the inside of the pot, water that runs straight through without wetting the soil, or a plant that wilts between waterings despite damp compost all point to a sizing issue. If a result flags this, the Pot Size Calculator guide explains how to work out the next size up in centimetres and litres.
What it cannot tell you
The checker works from the symptom and plant type you give it, and it ranks likely causes. Several things can produce the same visible sign, and it can point you towards the wrong one, particularly where more than one issue is happening at once, such as a plant that is both root-bound and underwatered. It does not identify pests or diseases with certainty, and it is not a substitute for professional advice where a plant is seriously unwell or where you suspect a pest infestation that needs specific treatment.
Using the result
Treat the ranked list as a starting point for working through the causes in order. Check the top cause against what you can see in the pot and the soil before acting on it, and use the linked care guide to get the watering, light or repotting detail right for that specific plant.