Our unique climate throws some serious curveballs at indoor plant enthusiasts. During our scorching summers, air conditioning sucks moisture out faster than a bushfire, while winter heating systems can drop indoor humidity to sahara-like levels. Your tropical mates—calatheas, ferns, and philodendrons—are used to steamy rainforest conditions sitting around 60-80% humidity, but most Aussie homes hover around a measly 30-40%.
This isn't just about plant aesthetics. When humidity drops too low, plants become stressed, making them vulnerable to pests like spider mites and scale insects—creating a cycle where frustrated gardeners reach for chemical sprays that can compromise family health.
While tropical plants often come from environments with 60–80% humidity, most homes don’t need to reach those levels for plants to stay healthy.
A more realistic target for indoor growing is around 50–60%, which supports plant health without increasing the risk of mould, condensation, or musty air.
Different plants respond differently, though. A simple way to gauge humidity needs is by looking at leaf thickness:
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Thin or delicate leaves lose moisture quickly and benefit from higher humidity
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Thicker, waxy or leathery leaves cope better in average household air
As a general guide:
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Aroids (Monstera, Philodendron, Anthurium): enjoy moderate to higher humidity
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Calatheas & Marantas: prefer consistent humidity and show stress quickly if air is too dry
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Ferns: appreciate extra moisture in the air
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Orchids: benefit from humidity but still need airflow around roots
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Succulents & cacti: prefer drier air and don’t need added humidity
Signs a plant may want more humidity include crispy leaf edges, curling leaves, or slowed growth. If leaves are yellowing or developing dark patches, however, excess moisture or poor airflow may be the issue instead.
The Family-Safe Humidity Solution
Perlite Tray Magic
This dead-simple technique can boost humidity by up to 15% around your plants using completely natural materials. Here's why it works brilliantly in Australian conditions:
What you'll need:
- A wide, shallow tray
- Perlite (medium grade) - those lightweight volcanic glass pebbles that won't harbour bacteria
- Clean water
The setup:
- Fill your tray with perlite—it's naturally antimicrobial and won't go mouldy like regular stones
- Add water until it sits just below the perlite surface
- Place your plant pot on top (the pot bottom shouldn't touch water)
- Watch the magic happen as water evaporates slowly, creating a perfect microclimate
The beauty of perlite is that it's sterile, lightweight, and designed for plant use—no nasty chemicals or treatments that could affect your family's air quality.
You’ll often see pebble trays recommended as a way to increase humidity. A pebble tray is simply a shallow tray filled with stones and water, with the pot sitting above the water line so roots stay dry.
As water slowly evaporates, it creates a small pocket of humidity around the plant.
We recommend perlite trays instead of traditional pebbles for a few reasons:
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Perlite is lighter and holds moisture across a larger surface area
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It dries more evenly, reducing stagnant water
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It’s less likely to trap organic debris that can encourage mould or pests
It’s also worth being realistic: trays don’t dramatically raise humidity across an entire room. They work best as a gentle, local boost, especially when combined with plant grouping and good airflow.
Misting and trays can help at a small scale, but they’re most effective when used as part of a broader approach rather than a single solution.
Any tray system should be checked regularly.
Empty and rinse trays occasionally to prevent insects breeding in standing water and to reduce fertiliser salt buildup. Keeping the area clean supports healthy humidity without introducing new problems.
Misting can temporarily increase surface moisture, but it isn’t a long-term solution for raising overall humidity.
It’s also not suitable for all plants. Plants with hairy or velvety leaves, such as African violets, can develop spotting or rot if water sits on the leaf surface.
If you do mist:
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Mist in the morning, so leaves dry during the day
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Use filtered or distilled water to reduce mineral marks
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Avoid misting in cool, poorly ventilated rooms
Think of misting as a short-term comfort measure rather than a replacement for proper humidity management.
Create Your Own Indoor Jungle Cluster
Plants are natural air purifiers and humidity generators through transpiration. Grouping your tropical plants together amplifies this effect, creating a self-sustaining humid microenvironment that benefits everyone:
For your plants: Higher humidity means healthier growth and natural pest resistance
For your family: More oxygen production and natural air filtration
For your wallet: Reduced need for expensive, energy-hungry humidifiers
If you only have a few humidity-loving plants, creating a microclimate can be more effective than trying to humidify an entire room.
Options include:
Glass cloches or domes
These trap moisture around a single plant, creating a stable humid pocket. Place them in bright, indirect light and lift the cover occasionally to allow fresh air in. Avoid direct sun, which can cause overheating.
Terrariums
Fully or partially enclosed containers work well for small tropical plants, provided there’s some ventilation and drainage.
Clear storage tubs as mini-greenhouses
A low-cost option for cuttings or smaller plants. Open regularly for airflow to prevent stale air or fungal issues.
Plant cabinets
Enclosed cabinets with controlled airflow are becoming popular for collectors. These can work very well when humidity and ventilation are balanced, but they still need regular monitoring.
With any enclosed setup, airflow is just as important as moisture. Stagnant air is far more likely to cause mould than humidity alone.
The Mould Prevention Game Plan
Here's where many plant parents get nervous about increasing humidity—and rightfully so. Mould can be a serious health concern, especially for family members with respiratory sensitivities. The key is creating moving humidity, not stagnant moisture.
Smart Airflow Solutions
Gentle circulation is your best mate here. A quality clip-on fan positioned to create gentle air movement around your plant cluster prevents stagnant air while maintaining that precious humidity. This isn't about creating a windstorm—just enough movement to keep things fresh.
Strategic spacing matters too. Keep plants at least 10-15cm away from walls and furniture. This simple trick allows air to circulate naturally and prevents moisture from building up in corners where mould loves to set up camp.
Monitor Like a Pro
Guesswork is the enemy of both plant health and family safety. A decent temperature and humidity monitor takes the guesswork out completely. You're aiming for that sweet spot of 50-60% humidity—high enough for tropical plants to thrive, but not so high that you're inviting mould problems.
Pro tip: If you're seeing condensation on windows or walls, you've gone too far. Scale back the humidity sources and increase air circulation.
Humidifiers can be effective, especially in very dry climates or during winter, but they need to be used carefully.
To reduce the risk of mould:
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Keep humidity below the point where windows or walls develop condensation
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Place the humidifier away from walls, furniture, and ceilings
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Clean the unit regularly to prevent mineral buildup and bacteria
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Use filtered water if possible
A hygrometer is essential when using a humidifier. If levels climb above your target range, reduce output or increase ventilation.
The Australian Advantage
Seasonal timing is everything in our climate. Right now, as we head into the warmer months, your plants are naturally more active and can handle—actually crave—higher humidity levels. This is the perfect time to establish these humidity-boosting habits before the harsh summer air conditioning kicks in.
Your tropical plants will reward you with:
- Larger, more vibrant leaves
- Natural resistance to common pests
- Faster, healthier growth
- Those Instagram-worthy unfurling moments we all love
FAQ
Do pebble trays actually work?
They provide a small, local humidity boost. They’re most effective when combined with grouping and airflow.
Is misting enough for tropical plants?
On its own, misting is usually not enough to raise ambient humidity for long periods.
What humidity is too high for a bedroom?
Consistently high humidity that causes condensation can increase the risk of mould. Staying within a moderate range and ensuring airflow is key.
Can high humidity cause mould indoors?
Yes — especially when paired with poor ventilation. Balanced humidity and airflow prevent this.
Which plants need 60% humidity or more?
Many calatheas, ferns, and some aroids prefer higher humidity, but most adapt well to slightly lower levels in a healthy home environment.
Beyond Plant Health: Family Benefits
Creating optimal humidity isn't just about plant care—it's about creating a healthier home environment. Proper humidity levels can help with:
- Reducing dry skin and respiratory irritation during our harsh summers
- Natural dust control (humid air traps airborne particles)
- Lower static electricity (ever noticed how your clothes stick together more in dry weather?)
Start simple: Grab some perlite and set up your first humidity tray this weekend. Add a basic monitoring system to track your progress, and consider a gentle fan for air circulation if you're grouping multiple plants.
The result? Lush, thriving tropical plants that contribute to a healthier home environment—all achieved naturally, without compromising your family's wellbeing or breaking the bank on expensive equipment.
And when the seasons flip, humidity won’t be the only battle. If you’ve ever watched your indoor plants sulk through short, cloudy days, Tired of Watching Your Indoor Plants Struggle Through Another Cloudy Australian Winter has the hacks you’ll need to keep them powering on year-round.
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