The only way that I found to use leylandii clippings was to lay them directly as a path material in the veggi garden. They are too soft for my shredder so I now take them directly to the re-cycling centre.

I wouldn't recommend using them as a mulch, will take to much nutrient from the soil to rot down.

Regarding composting the offcuts of leylandii, if you shred them up very small and add to a hot composting system, they'll rot down within 3-6 months, but if you have the more usual cold composting system, even shredded up, they'll take 1-5 years to degrade.

What happens to the chemical in them which inhibits the growth of other plants & enables them to colonise whole hillsides? Surely it must be still present & in the resulting compost? People take all the stuff they wouldn't dream of putting in their own heap to the Council, who I'm sure sell it on, that's why there is now such poor quality compost out there. I had one bag which had very little soil in it & just nothing would grow in it, so waste of money.

Feverfew, there is no evidence that leyland cypress are allelopathic, in other words, they do not 'poison' the soil around them to prevent other plants growing. Rather, they create such a dry, shaded environment that nothing else CAN grow nearby.

Thankyou for that info Bamboo, always ready to learn! I really thought that they were alleopathic. By the way, I think you are very knowledgeable. I read your replies to the gardening Questions.

;-))