If your deck goes green and slippery every winter, you're not alone. In our damp NZ climate, moss, mould and lichen take hold fast on timber, composite and concrete — and by the time it's slippery underfoot, it's a safety issue as much as an eyesore.
The good news: you don't need a water blaster (which can chew up soft timber and force water into the grain), and you don't need to spend a Saturday on your hands and knees. Here's how to get it done properly.
Why your deck keeps going green
Moss and mould need three things: moisture, shade and a food source (dust, pollen, organic film). Kiwi decks tick every box, especially on the south side of the house. Water blasting only removes the surface growth — the spores and roots stay behind, so it's back within months. To actually stop the regrowth cycle, you need to kill the growth at the root, not just blast off the top.
What you'll need
A no-scrub outdoor treatment does the hard work for you. Our Moss and Mould Remover – Heavy Duty No-Scrub Outdoor Cleaner is designed exactly for this: you apply it, leave it, and let the weather rinse it. It works on decking, paths, concrete, pavers and fences.
Step-by-step
1. Sweep first. Clear leaves and loose debris so the treatment reaches the surface.
2. Apply on a dry, still day. Dilute and spray evenly across the affected area with the Moss and Mould Remover. No scrubbing needed.
3. Walk away. The treatment keeps working over the following days and weeks — the moss and mould dies off and washes away with normal rain.
4. Rinse only if you want to speed things up. A light hose-down lifts loosened growth, but there's no need for high pressure.
Water blasting vs treatment: which wins?
Water blasting is fast and satisfying, but it's a surface fix that can damage soft timber and leaves the roots behind. A chemical treatment is slower to show results but kills growth at the source, so your deck stays clean far longer. For most homes, the no-scrub treatment is the better long-term call — and it's kinder to your decking.
Keep it clean for good
Once your deck is clear, a light annual application before winter keeps regrowth away. While you're protecting outdoor surfaces, it's worth thinking about your outdoor fabrics too — our Fabric Protector range adds a water- and stain-repellent shield to outdoor cushions and covers, so the whole space stays fresher through the wet months.
Got green paths or a mouldy concrete patio as well? The same Moss and Mould Remover handles those too — one bottle, whole backyard sorted.
