Module 1 · Light — the one that actually matters
lesson 1.3
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Lesson 1.3 · 5 min
The shadow test
After this you can grade the light in any spot in about ten seconds, for free.
You do not need an app or a meter to start. On a bright day, around midday, hold your hand about thirty centimetres above the spot where the plant will sit and look at the shadow it casts. The sharpness of that shadow tells you the light level — sharp edges mean strong light, blurry edges mean weak light.
The shadow test
| Shadow you see | Light level | What belongs there |
|---|---|---|
| Crisp, hard-edged shadow | High / bright light | Cacti, succulents, most flowering plants |
| Soft-edged, fuzzy shadow | Medium / bright indirect | Pothos, monstera, most foliage plants |
| Faint, barely-there shadow | Low light | Snake plant, zz, cast-iron — survivors only |
| No shadow at all | Too dark to grow | Nothing thrives here — add a lamp or move on |
Do the test at a couple of times of day if you can, because a spot that is bright at noon can be dark by four. The light audit tool below turns this into a repeatable check and lets you save a reading per spot, so you stop guessing and start matching plants to places you have actually measured.