The short answer
It should not. Garden damage comes from run-off, so the job is planned around where the water goes. Plants and furniture are covered or moved, loosened moss is bagged rather than washed down, and any biocide is applied to the terms of its authorisation. Delicate beds directly under the eaves are the place to talk through before work starts.
The roof sits above your borders and lawn, so whatever comes off it has to be caught, not just cleared. Planning the ground comes before touching the tiles.
What actually reaches the garden
Three things come off a roof during a clean: loose moss and grit, rinse water, and whatever is left of any treatment product. Each needs a different answer.
Is the moss itself a problem on the ground?
No. Moss and lichen are plant material, and a heap of it is harmless in a compost bin. The trouble is volume and mess. A large amount dropping into a flower bed buries small plants, and moss swept into a gutter ends up in the downpipe and the drain. So we sweep it down the slope into a bag or onto a sheet rather than leaving it to fall.
Grit and the fine dirt that lived under the moss follow it. That is the reason a roof clean should be done from the top down: the roof first, then the gutters, then the ground, which is swept and left tidy.
Rinse water is the lightest of the three where the work is done by hand. A hand clean needs little water, so there is far less run-off to manage than with a long wash.
We tell you each day what is being done, so you can move pots or pets without surprises.
Covering plants and setting up the ground
Before anything starts we walk the edges of the house with you. Beds under the eaves, a greenhouse, a pond, a vegetable plot and a washing line all change how the ground is set up.
How are plants protected?
Delicate plants near the wall are either moved by you beforehand or covered with breathable sheeting, tied loosely so nothing is crushed, which keeps debris off without trapping heat on a warm day. Furniture, barbecues and children's toys are best moved right away from the house. Dust sheets or tarpaulins go down over patios and paths where moss will fall, and are lifted and shaken out once work stops for the evening.
Where the roof overhangs a bed that cannot be moved, we can work the downhill edge by hand and bag the debris instead of letting it drop. Lawns need less care than borders, since grass shrugs off a light covering of moss, but we rake it off afterwards, and any patch of gravel gets the same sweep.
If there is a water butt or pond close by, the separate answer on roof cleaning and water butts covers what changes.
Products, run-off and the rules they sit under
Moss treatments are biocides, meaning they are made to kill, and that is what makes their run-off worth thinking about. Article 17(5) of the retained Biocidal Products Regulation ties each use to the terms the product was authorised on, including where it can go.
Can treatment drift onto plants?
It can if it is sprayed carelessly in wind or applied far beyond need. HSE adds that professional-only products are not for the public. So we pick a product to suit the job and read it against its label, keep the quantity to what the roof needs, and hold off in wind or when heavy rain is forecast.
The product label, not this page, has the last word on any specific product. If you grow vegetables or keep an organic plot, tell us when you book and we plan around it.
For the full picture of the work, see roof cleaning and moss removal, and for the method behind it soft wash roof cleaning.
Tidying up and what to check afterwards
The job is not finished when the roof is clear. The ground, the gutters and the downpipes all get a final look.
What does a tidy finish look like?
Sheets are removed and shaken out away from the beds. Debris is swept off paths, patios and gutters, bagged and taken away with the rest of the waste. The downpipes are run through to confirm that nothing is stuck. Anything that was moved is put back with your agreement.
For the next few weeks keep an eye on the beds below the eaves, especially if the weather has been dry, and give them a watering if you wish. A scorched leaf or a patch of pale growth is worth telling us about at once; we can look at what was used and where the run-off went.
Moss will return in time if the shade and damp that fed it remain, so a clean is repeated when needed, not on a fixed calendar. Our answer on moss growing back after cleaning explains why.
To plan around your own garden, send a photo of the beds under the eaves. The survey that follows ends in one written total that already allows for the ground protection.
Garden worries answered
Should I cut back plants before the roof is cleaned?
Plants brushing against the walls or gutters are easier to protect if trimmed back a little, which also gives access for ladders and sheeting. Leave larger shrubs in place and we will cover them. Tell us what matters most to you, such as a favourite rose or a new planting, and we work around it.
Can I keep using the garden while the clean is under way?
Keep children, pets and washing away from the area directly below the work, and stay out of any section we have sheeted. The rest of the garden is fine to use. We tell you each day where we are working, so you know which part of the garden to avoid.
The full picture: Roof cleaning and moss removal in Taunton ยท More short answers