Lawn Sweeper: What It Does That a Rake and Mower Can't

A lawn sweeper is a simple thing: brushes geared to the wheels, flicking debris up into a bag behind. No engine, no suction, nothing to service.

It is genuinely excellent at one job — clearing dry leaves and pine needles from a large lawn — and noticeably poor at several others people buy it for.

What it actually is

The brushes sit under a frame and are geared to the wheels. Roll the sweeper forward and they spin backward, throwing debris over the top of the brush housing into a fabric hopper.

That is the whole mechanism, and two consequences follow:

• Speed matters. Too slow and the brushes do not spin fast enough to throw debris over the lip. Most tow-behind sweepers want 3 to 5 mph — a brisk walking-to-slow-driving pace.
• Nothing is sucked. Anything the brushes cannot flick, they simply push along the ground.

Where it beats the alternatives

The comparison that matters most is against a mower bagger. A bagger holds a few cubic feet and fills in minutes when leaves are down, so you spend the afternoon walking to the compost heap. A tow-behind sweeper holds 12 to 26 cubic feet and does not require you to mow at all — which matters in late autumn when the grass has stopped growing but the leaves have not stopped falling.

The limitation nobody mentions until after

Wet leaves. They stick to the turf and to each other, and the brushes skid over them or roll them into sausages. A sweeper is a dry-weather tool.

In a wet autumn that means waiting for a dry, breezy day, or blowing the leaves into rows first and letting them dry before sweeping. It does not replace a rake for the soggy corners.

Heavy debris. Acorns, conkers, cones and thick twigs are often too heavy to be flicked up over the brush housing. Some go in; many get pushed along.

Thick, matted layers. A sweeper takes a layer at a time. Six inches of leaf fall needs several passes, and expecting one pass to clear it is how people conclude the machine is useless.

Push or tow-behind

Push sweepers — around 21 to 26 inches wide, hoppers of 5 to 8 cubic feet. Cheap, compact, no tractor required. The catch is effort: it is all on you, and a full hopper is heavy. Sensible up to about a quarter acre.

Tow-behind sweepers — 38 to 50 inches wide, hoppers of 12 to 26 cubic feet. Much faster, much bigger, and no effort beyond driving. They need a ride-on or lawn tractor with a hitch, and they need somewhere to live in the winter, because they are large.

Half an acre is roughly where the tow-behind starts to be the obvious answer.

Getting good results

• Mow first, if the grass is long. Long grass swallows leaves and blocks the brushes.
• Keep a steady, brisk pace. Slowing down reduces pick-up rather than improving it.
• Overlap passes by a few inches — the outer edges of the brush do less work.
• Empty the hopper before it is packed. A full bag stops debris entering and it all gets pushed along instead.
• Store it dry, and out of sunlight if you can. UV is what kills the fabric hopper.

What to do with what you collect

Do not bin it. Leaves are the single most useful free material a garden produces.

Leaf mould — leaves stacked in a wire cage or a bin bag with a few holes, left for a year or two, break down into a superb soil conditioner. It is slow because leaves rot by fungal action rather than bacterial, which is also why they are worth separating from the compost heap.

Compost — mix them in as the brown, carbon-rich component alongside green material like grass clippings. A sweeper full of shredded leaves and clippings mixed together is close to an ideal ratio already.

Mulch — a few inches over beds through winter, where they suppress weeds and are pulled down by worms. Related: worm castings.