I would add it to your compost pile if you have one. I would not take the chance of digging great quantities of viable moss directly into your garden soil, it might take hold in your flower or vegetable bed and be very difficult to eradicate from then on.

I have done this in the past and it does rot down well but it takes time and needs to be well covered to stop it photosynthesising. Luckily it cant root as they don't have any. any that is on the surface can just be turned over. But as Loosestife says better to put on compost heap [no light to keep it going].

If you've got lots of hanging baskets or wall mangers to plant up later, keep the moss moist and use it to line them with. Otherwise, compost it.

Pleased to know that roof moss can be composted. In the past, it has gone in my council green waste bin because I read somewhere that it takes too long to break down. I will always take notice of my GOY friends!

Just thought I might mention that once you have taken the moss off the roofing of your outbuildings, check the roofing. Moss and the action of its removal can displace shingles and cause water leaks which can lead to wood rot and cracking.

What sort of roof is it? I'd leave the moss in place - it will be providing a little eco-system for insects and birds.

PS if the roof is visible you could even make a feature of it as a green roof by adding sedum, sempervivum etc. do an Internet search for 'green roof' - there are several mat systems (like turf) to give you an idea of the types of plants you could use - they don't need lots of soil. A photo of the roof would be useful.

But if you don't want the moss to regrow I read that fixing a copper strip along the top of the slates will prevent it.

It's now five years since the last comment, but here is my penn'orth. I live near the sea and the seagulls - I assume it's them - scratch the moss off the roof, (tiled). I picked it up and though hmm, I wonder if that would be good for the garden. It is usually pretty dried out when it arrives so probably not going to take over the garden. I have been just tossing it in to the beds to add a little something to the soil.

Just goes to show you, answers to garden questions, like hope, springs eternal.