Most tropical houseplants prefer a relative humidity of 40 to 60%. The majority of popular species, Monsteras, Pothos, Philodendrons, Hoyas, tolerate the 40 to 50% humidity typical of a normally heated UK room without significant issues. More demanding humidity-lovers like Calatheas, Ferns, Anthuriums, and most orchids prefer 50 to 70% and will show brown leaf tips and crispy edges at consistently lower levels. Succulents and cacti, by contrast, prefer low humidity (20 to 40%) and do poorly in persistently damp conditions.
What Humidity Levels Are Like in UK Homes
In a UK home with central heating running through winter, indoor humidity typically drops to 30 to 45%. This is adequate for tolerant species but consistently below the preferred range for humidity-sensitive plants. In summer, UK homes without air conditioning tend to sit at 50 to 60%, which is comfortable for most tropical plants. The most challenging period for humidity-sensitive plants is October to February, when heating runs longest and outdoor moisture levels are lower.
How to Increase Humidity Around Plants
The most effective methods for raising humidity around houseplants in the UK are pebble trays, plant grouping, and humidifiers. Plant grouping raises local humidity through transpiration from the surrounding plants. A small ultrasonic humidifier provides the most reliable and measurable humidity increase, particularly for densely planted humidity-sensitive collections.
Misting is widely recommended but provides only a brief humidity spike of a few minutes. It isn't an effective substitute for a pebble tray or humidifier for plants that genuinely need higher humidity. See our full guide on whether misting is beneficial.
Which Plants Need High Humidity
Calatheas and Marantas are the most commonly kept high-humidity plants. They prefer 60 to 70% and show brown leaf tips and crispy edges at lower levels. Maidenhair Ferns require sustained high humidity (65 to 80%) and are among the most demanding common houseplants in this respect. Boston Ferns, Anthuriums, and most Orchids prefer 55 to 70%.
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Which Plants Prefer Lower Humidity
Succulents, cacti, Desert plants, Sansevierias, and ZZ Plants prefer 20 to 40% humidity. They are native to arid or semi-arid environments and do poorly in persistently humid conditions that favour fungal disease. The dry air of a centrally-heated UK home in winter actually suits these plants well. Grouping them with high-humidity species in a humidified area is not ideal for their care.