When plants and mould take hold in an eavestrough, the trough is telling you something. This field guide helps you identify what is growing, remove it safely and stop it returning.
In This Article
Why anything grows in a trough at all
Growth needs four things: seeds, moisture, light and something to root in. A neglected trough provides all four. Fallen leaves, seed pods and roof grit break down into a dark, compost-like layer that holds water like a sponge. Wind and birds deliver the seeds, and spring warmth wakes them up.
That is why growth shows up in April, May and June, after maple keys and catkins have landed in last fall's leftovers. It is also why it comes back in the same places. Where water stands, a wet layer stays wet.
A field guide to what is growing
| What you see | What it likely is | What it tells you |
|---|---|---|
| Tiny trees with two leaves, often pale green | Maple or other tree seedlings | Seed pods landed in damp debris. Roots can work into seams, so remove them early |
| Grass or weeds along the trough | Wind-blown seed in a soil-like layer | There is a thick layer of debris, and it has been there a while |
| A soft green cushion | Moss | The spot is damp and shaded. Moss on the roof above can shed into the trough |
| A green or slimy film on the metal | Algae | Constant moisture, often on a shaded side |
| Black or grey spots on wet debris | Mould or mildew | Rotting leaves in standing water |
| Mushrooms or a fuzzy white web in the muck | Fungi | Long-term decay, so the trough has probably not been cleared for a full season or more |
Timing helps with identification. Seedlings tend to show from April through June. Moss and algae thrive in the damp, shaded weeks of summer. Mushrooms and mould often appear in autumn, once a wet mat of leaves has been sitting for a while. A trough that shows several of these at once has been left through more than one season.
The dark streaks that run down the outside face of a trough are a different problem. Black streaks on gutters covers their causes and removal.
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Handling mould and dust safely
Dry, mouldy debris throws off dust and spores when you disturb it. Take simple precautions.
- Wear cut-resistant gloves, safety glasses and a dust mask.
- Dampen the debris lightly with a hose before you scoop, so it does not become airborne.
- Work with the wind at your back, and stay on the ladder no longer than you have to.
- Bag the debris, wash your hands and wash the clothes you wore.
If anyone in the household has asthma, a mould allergy or a weak immune system, they should not do this job. Hand it to someone else, or to a crew.
Removing growth properly
- Take out the plants with their roots, along with the layer they are rooted in. Cutting off the tops leaves the seedbed behind, and regrowth follows.
- Scoop the whole muck layer down to bare metal, and bag it. Follow your municipality's current yard-waste rules.
- Scrub slimy film with a soft brush. If you use a cleaner, choose one labelled for your trough's finish, keep it off plants and rinse well, following the label.
- Flush the run with a hose, from the high end toward the downspout.
- Watch where the water lingers. Any puddle that stays is where growth will start again.
Do not pull hard on a stubborn plant. A tug that bends a trough or breaks a seam creates a bigger problem than the plant did.
Stopping it coming back
- Fix the slope. Standing water is what keeps the layer wet. Why gutter pitch matters explains how to spot a low spot.
- Clean before the seed drop and after the leaf drop. A trough with little debris has no seedbed.
- Treat the roof. Moss and algae on shaded shingles shed into the trough. Moss and lichen removal from roofs covers safe methods, and roof cleaning is a specialist job.
- Trim overhanging branches with an arborist to let in light and cut the debris. Stay clear of powerlines.
- Consider guards if the trees are not going anywhere. They reduce what gets in, though fine seeds and grit can still pass.
D&D Home Services offers gutter cleaning from $125 for a typical Kitchener-Waterloo home, and roof cleaning for the moss above it. Quotes are free and confirmed in writing before work begins.
Key Takeaways
- Trough growth needs seeds, moisture, light and a layer of rotting debris, which is why it appears in spring after seed pods land.
- Seedlings, grass, moss, algae, mould and fungi each point to a different level of neglect or dampness.
- Wet down mouldy debris, wear gloves, glasses and a dust mask, and keep anyone with asthma or a mould allergy off the job.
- Remove plants with roots and the whole muck layer, then fix any low spot that holds water, since growth returns there.
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