How to use a pebble tray to lift humidity for indoor plants
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Brown crispy edges on a fern or a calathea catch a lot of people out, because the obvious answer is to water it more and the actual problem is the air rather than the soil. Tropical plants come from places where the air is damp most of the year, and the inside of an Australian house in the middle of summer, or with a heater running through winter, is nothing like that. A pebble tray is the cheapest way to take the edge off it.
What a pebble tray is
A shallow tray of pebbles with water sitting in the bottom of it, with the plant pot standing on top of the pebbles rather than in the water. The water evaporates, which lifts the humidity in the small patch of air right around the plant. That is the whole idea, and there is nothing else to it.
Which plants want one
Ferns, calatheas, monstera, peace lilies and most things with thin soft leaves are the ones that notice. Succulents, cacti and snake plants do not want it and are better off without, because they are built for dry air and extra humidity around them is asking for rot.
Setting one up
- Find a shallow tray. A large pot saucer is ideal and it is what most people end up using, and it wants to be a fair bit wider than the pot so there is water surface on all sides.
- Fill it with pebbles. One layer is plenty. Decorative pebbles look better than gravel if the plant is somewhere you look at.
- Add water up to just below the top of the pebbles. The pot has to sit on stone, not in water, because a pot standing in water wicks it up into the mix and you have swapped a dry air problem for a wet root problem.
- Stand the pot on top. Check that the base of the pot is clear of the waterline once the pot is on there, because a heavy pot settles down between the pebbles.
- Top the water up. Once a week is usually about right, more often in a hot dry week.
What it will and will not do
A pebble tray lifts the humidity in a small pocket of air immediately around the plant. It will not change the humidity of the room, and it will not save a plant that is sitting in a draught from an air conditioner or right beside a heater, because moving air carries the damp away as fast as it comes off the tray. Move the plant out of the draught first and then give it a tray.
It also will not stand in for the basics. A plant still needs the right light, a free draining mix and sensible watering, and the tray is something you add on top of all that rather than instead of any of it.
A trick worth knowing
Group the humidity lovers together on one big tray. Plants lose water through their leaves all day, so a cluster of them holds a damper pocket of air between them than any one of them manages alone, and it looks better on a sideboard than five pots dotted around the house.
Keeping it clean
Standing water grows a film after a while, so tip the tray out and rinse the pebbles every month or two. If mosquitoes are about in summer, keeping the water below the top of the pebbles and refreshing it weekly is enough to stop them using it.
Shop related products
- Brunnings Sphagnum Moss 150g. Holds moisture beautifully as a top dressing on a pot, which works alongside the tray.
- Brunnings Premium Potting Mix 36L. The general mix for ferns and other leafy indoor plants.
- Brunnings Horticultural Charcoal 5L. Chunky and open, so it keeps a damp mix sweet rather than sour.
- Maxicrop Indoor Plant Food Concentrate 250ml. A gentle seaweed based feed for anything growing indoors.
Did you know we also stock the pebbles and the trays in the shop. Decorative pebbles in black, snow white and multicolour, in 5mm to 10mm and 10mm to 20mm, plus pot saucers from a 200mm terracotta one up to 500mm plastic. None of that is on the website, so give us a ring on (08) 8536 4333 to check what is on the shelf.
The mixes and the plant food are in the garden centre, and if you bring a photo of the leaf edges in we will tell you whether it is humidity or something else.
More from the garden
- How to stop root rot in your indoor plants
- How much light do indoor plants actually need
- How to care for a monstera and get the split leaves
A tray of stones and a bit of tap water is about as unglamorous as plant care gets, and it works, which is good enough for me. Ask me in the shop, I am usually there.
Cheers,
Candeece
