Shredders have been around for a long time, breaking down prunings from trees and shrubs to enable you to reduce your tougher garden debris into a useful mulch quickly and effectively.

But the price and quality of shredders varies enormously and now Which? Gardening, the Consumers’ Association magazine, has done some research to find out which shredders perform best and to let gardeners know what features to look out for when buying a shredder.

“A decent machine will cope with both woody branches and green twigs without jamming, shred a large amount quickly and quietly, and produce fine shreddings ready to use as a mulch or to add to your compost,” the magazine reports.

Testers fed easy garden material such as straight, fresh branches through the ten shredders on trial, weighed the resulting shreddings and rated how finely they had been chopped. They then shredded different materials including conifer prunings, spiny and woody branches and soft, fibrous plants and assessed if shredders became blocked, as well as assessing the machines for ease of use, noise and ease of moving and storage.

Those voted the ‘Best Buy’ shredders included the Bosch AXT 22 D (£280), a quiet roller shredder which proved to be the best for all types of material; the Bosch AXT 23 TC (£400), a roller shredder which was best for more woody material, and the Al-Ko 2500R Power Slider (£229), which proved best for fine shredding.

There are two main types of shredders available – the impact shredder and the roller/turbine shredder.

Impact, or rapid, shredders chop branches very finely with a spinning blade and are lighter and easier to move than roller shredders, but are also noisier.

The blades will go blunt over time, so make sure replacements are available when you buy an impact shredder. Most don’t come with a collector so you’ll have to improvise with a plastic sheet or tub.

Roller shredders are quieter machines which draw in garden debris, chopping it up and crushing it against a metal plate with a drum of blades. They are generally quieter and more compact, but they shred more coarsely.

When buying a roller shredder, make sure you can safely and easily access the blades to clear blockages, as they can block more easily than impact machines. Also check that the shredder outlet isn’t obstructed as some have a plastic grid over the outlet for safety, but this may lead to debris catching and blocking the machine.

To get the best out of your shredder, shred material shortly after pruning as the wood will be softer and easier to break down, and put the thicker end of branches through the machine first.

Prevent blades from clogging by alternating between sappy green waste and drier woody material, and always clean out the shredder after breaking down green waste or the blades will clog.

Try to keep the shreddings from different types of materials separate – woody shreddings are ideal as mulches, while green matter is better for the compost heap.