When to feed and how much

Two rules cover almost everything. Feed only during active growth — spring and summer for most houseplants — and feed at a fraction of the strength the bottle tells you. A plant that is actively pushing out new leaves can use a light, regular top-up. A plant that is resting cannot, and the extra just accumulates in the soil.

Why stop in winter? Because most houseplants slow right down when the days are short and the light is low. They are barely growing, so they have little use for extra minerals. Keep feeding through winter and you are pouring salts into soil that cannot spend them — which is exactly what causes the build-up in the next lesson. The fertiliser calculator below turns a label rate into your half-strength dose so you are not doing the maths by eye.