Guides
How to Use Potassium Soap Against Aphids
Potassium soap works by contact. Wet the underside well and avoid burning in full sun.
Potassium agricultural soap is not a plant perfume: it dissolves the soft cuticle of aphids. If you don't wet the bug, it does nothing. If you spray at noon in August, you can burn the leaves.
Preparation
Dilute according to the label (one liter is enough for many backpacks). Use lukewarm water, avoid extreme hardness if possible. Do not mix with copper solutions in the same mixture unless authorized by the manufacturer.
Application
Evening or cloudy morning. Underside, shoots, and underside again. Gentle pressure. Repeat every 5-7 days because nymphs keep emerging. If there are ants, place gel around the perimeter or the aphids will return like protected livestock.
Limits
It is not systemic. Rain within two hours washes it away. In strong mealybug infestations, soap helps but is not enough alone. Test on 2-3 leaves if the plant is sensitive (some ficus and ferns may complain).
What We Recommend at Control Garden
Potassium agricultural soap 1 L, ready to dilute. It is the first resource in an edible garden when aphids have just appeared.
