PlantpH.
A logarithmic measure of acidity or alkalinity from 0 to 14, where 7 is neutral and each unit is a tenfold change in hydrogen-ion concentration.
What it means for your plants
Most soilless houseplant mixes perform best at about pH 5.5–6.5, where nutrients are most available. Hard tap water gradually raises media pH; check runoff with a meter or test kit before acting, and avoid household vinegar or baking soda.
IN PRACTICE
A gardenia watered for months with hard water develops yellow new leaves as rising pH locks up iron.
Put it into practice
Feed houseplants every 2–4 weeks in spring and summer, pause in low winter light, and never feed dry or damaged roots. A grower’s guide to dose, timing and warning signs.
Fertilizing houseplants: how much, how often and when to stop
