Brunnings Sphagnum Moss, and how not to rot an orchid

What sphagnum moss is for, and the mistake that comes with it

Sphagnum moss holds something like its own weight in water many times over, and that single property is the reason it works and the reason it kills things. Used on a plant that keeps drying out faster than you can keep up with, it's the answer. Used on a plant that was already getting enough water, it turns the root zone into a permanently damp sponge and the roots go black.

Work out which orchid problem you've actually got

A healthy orchid root is plump and firm, and it looks silvery when it's dry and turns green within a minute or two of being watered. That silver is normal and it fools a lot of people into watering a plant that's perfectly happy.

A genuinely dehydrated root is thin and papery, and it stays that way even after a good soak. A rotted root is the opposite, brown or black and squashy, and it collapses to a thread when you squeeze it. Those two look nothing alike once you've seen both, and they want opposite treatment, so it's worth tipping the plant out of the pot and having a proper look before you change anything.

Brunnings Sphagnum Moss is for the first of those. If the roots are already soft and dark, more moisture retention is the last thing that plant needs.

Where it earns its keep

• Around the roots of an orchid that dries out too fast, particularly a small plant in a big airy bark mix that water runs straight through.
• Mounting a staghorn or elkhorn, where there's no pot at all and the moss is the only thing holding moisture against the plant.
• Lining a hanging basket, which is the classic drying-out situation because wind gets at a basket from every side.
• Wrapping an air layer on a shrub you're propagating, where you need a damp pocket held against a cut for weeks.

Watering changes once the moss goes in, and this is the whole game

An orchid in bark wants watering often, because bark sheds water. The same orchid in sphagnum wants watering far less often, because the moss is still holding the last drink days later. If you move a plant into moss and keep to the old schedule, you'll rot it, and it'll look fine for a fortnight first.

The check is your finger rather than the calendar. Push it into the moss and if it comes out damp, leave the plant alone. Squeeze a pinch of the moss too, because moss that's holding water will release a drop and moss that's spent will crumble.

Pack it loosely as well. Sphagnum crammed in tight excludes the air an orchid root needs just as much as it needs the water, and a loose wrap gives you both. It breaks down over about a year or two, and once it's gone soggy and structureless it holds water without releasing it, so it wants replacing rather than topping up.

One thing not to do

Do not lay a wad of moss in the bottom of a pot as a reservoir. It does the same thing a layer of gravel does, which is raise the wet zone up into the root ball instead of lowering it, and you end up with the soggiest part of the pot sitting exactly where the roots are. If the plant dries out too fast, the moss goes among the roots or over the surface, never underneath as a sump.

Wear gloves, and this one is not optional

Sphagnum moss is the classic source of sporotrichosis, which most people know as rose gardener's disease. It's a fungal infection that gets in through a scratch or a splinter and it turns into a nasty, slow ulcer that needs weeks of medication to shift. Wear gloves when you're handling it and keep it away from any cut you've already got, then wash your hands properly afterwards. Damping the moss down before you pull it apart keeps the dust out of the air as well.

Shop related products

• Brunnings Sphagnum Moss 150g. For an orchid or a basket that dries out faster than you can keep up with.
• Brunnings Orchid Potting Mix 15L. The bark based mix most potted orchids are happier in.
• Brunnings Perlite 5L. For opening a mix up if the problem turns out to be the opposite one.
• Multicrop Take Root Cutting Powder. For the air layering job, where the moss holds the damp.

Did you know we carry gardening gloves in the shop, which is the thing you actually need before you open a bag of this. They're not listed online, so give us a ring on (08) 8536 4333 to check what's on the shelf, or have a look through the garden centre while you're in.

Read next

• How to stop root rot in your indoor plants
• Choosing a potting mix, and what the ticks on the bag mean
• Houseplants for a humid room, and what they actually do

I check orchid roots with my fingers rather than my eyes, because the silver ones look thirsty to me every single time and they almost never are.

Cheers,
Candeece

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