How much humidity does spiraea betulifolia 'tor' need?

Spiraea betulifolia 'Tor' is comfortable at 40-70% — which is ordinary indoor humidity in most homes. This is the good news people rarely hear: spiraea betulifolia 'tor' does not need a humidifier, a pebble tray or daily misting. Typical living rooms sit between 30% and 50%, so unless you are running heating hard in a very dry climate, the air you already have is fine.

Nothing to do — normal room air suits it. If your home does get very dry in winter (heating on constantly, static in the air), simply moving spiraea betulifolia 'tor' away from the radiator does more than any humidity gadget.

Buying humidity equipment spiraea betulifolia 'tor' does not need. Misting in particular raises humidity for only a few minutes, and repeatedly wetting the leaves invites fungal spotting — the effort is worse than doing nothing.

Crisp brown leaf edges and browning tips are the reliable tell. Yellowing whole leaves is usually a watering issue rather than dry air, and slow growth in winter is normally low light — humidity gets blamed for a lot it does not cause.